UglyToad.PdfPig.DocumentLayoutAnalysis

Useful extensions.

Returns a specified number of contiguous elements from the start of a sequence.

The type of the elements of . An to return elements from. The number of elements to return. An that contains the specified number of elements from the start of the input sequence.

Bypasses a specified number of elements in a sequence and then returns the remaining elements.

The type of the elements of . An to return elements from. The number of elements to skip before returning the remaining elements. An that contains the elements that occur after the specified index in the input sequence.

Sorts the elements in a using the specified .

The type of the elements of . The to sort. The implementation to use when comparing elements.

Returns the element at a specified index in a sequence.

The type of the elements of . The to get the element from. The index of the element to retrieve. The element at the specified position in the sequence.

Clustering Algorithms.

Algorithm to group elements using nearest neighbours. Uses the nearest neighbour as candidate.

Letter, Word, TextLine, etc. Elements to group. The distance measure between two points. The function that determines the maximum distance between two points in the same cluster. The pivot's point to use for pairing, e.g. BottomLeft, TopLeft. The candidates' point to use for pairing, e.g. BottomLeft, TopLeft. Filter to apply to the pivot point. If false, point will not be paired at all, e.g. is white space. Filter to apply to both the pivot and the paired point. If false, point will not be paired at all, e.g. pivot and paired point have same font. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

Algorithm to group elements using nearest neighbours. Uses the k-nearest neighbours as candidates.

Letter, Word, TextLine, etc. Elements to group. The k-nearest neighbours to consider as candidates. The distance measure between two points. The function that determines the maximum distance between two points in the same cluster. The pivot's point to use for pairing, e.g. BottomLeft, TopLeft. The candidates' point to use for pairing, e.g. BottomLeft, TopLeft. Filter to apply to the pivot point. If false, point will not be paired at all, e.g. is white space. Filter to apply to both the pivot and the paired point. If false, point will not be paired at all, e.g. pivot and paired point have same font. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

Algorithm to group elements using nearest neighbours.

Letter, Word, TextLine, etc. Array of elements to group. The distance measure between two lines. The function that determines the maximum distance between two points in the same cluster. The pivot's line to use for pairing. The candidates' line to use for pairing. Filter to apply to the pivot point. If false, point will not be paired at all, e.g. is white space. Filter to apply to both the pivot and the paired point. If false, point will not be paired at all, e.g. pivot and paired point have same font. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

Depth-first search https://en.wikipedia.org/wiki/Depth-first_search

Algorithm that retrieve blocks that are labelled as decoration (e.g. headers, footers) for each page in the document, using a content and a geometric similarity measure. Decoration blocks are blocks that contains information such as author names, publication titles, page numbers, etc. They are printed repeatedly at the border of each page, usually placed inside headers or footers, but sometimes also at the left or right edge of the page. See section 5.1 of 'Unsupervised document structure analysis of digital scientific articles' by S. Klampfl, M. Granitzer, K. Jack, R. Kern.

Get blocks that are labelled as decoration for each page in the document, using a content and a geometric similarity measure. Decoration blocks are blocks that contains information such as author names, publication titles, page numbers, etc. They are printed repeatedly at the border of each page, usually placed inside headers or footers, but sometimes also at the left or right edge of the page.

The s in the document. All of them are needed for the algorithm to work. Minimum similarity score to decide wether a block is labelled as decoration or not. Number of blocks in a page to be considered when looking for decoration blocks. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

The s in the document. All of them are needed for the algorithm to work. Minimum edit distance normalised. A value of 0 means both strings are exactly equal. Minimum similarity score to decide wether a block is labelled as decoration or not. Number of blocks in a page to be considered when looking for decoration blocks. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

The s of every pages in the document. All of them are needed for the algorithm to work. Minimum similarity score to decide wether a block is labelled as decoration or not. Number of blocks in a page to be considered when looking for decoration blocks. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

The s of every pages in the document. All of them are needed for the algorithm to work. Minimum edit distance normalised. A value of 0 means both strings are exactly equal. Minimum similarity score to decide wether a block is labelled as decoration or not. Number of blocks in a page to be considered when looking for decoration blocks. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

[The content similarity] is calculated from the normalized edit distance between the two content strings, where digits are replaced with “@” chars. A content similarity of 1 is reached when both strings are exactly equal.

The geometric similarity is the area of the intersection between the two boundingbox rectangles divided by the larger of the two boundingboxes.

This similarity score is a value in the range [0,1] and given by the product between the content and the geometric similarity.

If the document has more than three pages, we compare blocks on the next or previous page with an even or odd number, depending on whether the current page number is even or odd, to account for cases with a two-sided layout.

Current page number. Total number of pages in the document.

Contains helpful tools for distance measures.

The Euclidean distance is the "ordinary" straight-line distance between two points.

The first point. The second point.

The weighted Euclidean distance.

The first point. The second point. The weight of the X coordinates. Default is 1. The weight of the Y coordinates. Default is 1.

The Manhattan distance between two points is the sum of the absolute differences of their Cartesian coordinates. Also known as rectilinear distance, L1 distance, L1 norm, snake distance, city block distance, taxicab metric.

The first point. The second point.

The angle in degrees between the horizontal axis and the line between two points. -180 ≤ θ ≤ 180

The first point. The second point.

The absolute distance between the Y coordinates of two points.

The first point. The second point.

The absolute distance between the X coordinates of two points.

The first point. The second point.

Bound angle so that -180 ≤ θ ≤ 180.

The angle to bound.

Bound angle so that 0 ≤ θ ≤ 360.

The angle to bound.

Get the minimum edit distance between two strings.

The first string. The second string.

Get the minimum edit distance between two strings. Returned values are between 0 and 1 included. A value of 0 means that the two strings are indentical.

The first string. The second string.

Find the index of the nearest point, excluding itself.

The reference point, for which to find the nearest neighbour. The list of neighbours candidates. The distance measure to use. The distance between the reference element and its nearest neighbour.

Find the index of the nearest line, excluding itself.

The reference line, for which to find the nearest neighbour. The list of neighbours candidates. The distance measure between two lines to use. The distance between the reference element and its nearest neighbour.

Checks if each letter is a duplicate and overlaps any other letter and remove the duplicate, and flag the remaining as bold. Logic inspired from PdfBox's PDFTextStripper class.

Letters to be processed. Letters with no duplicate overlapping.

Alto 4.1 (XML) text exporter. See https://github.com/altoxml/schema

Alto 4.1 (XML). See https://github.com/altoxml/schema

Extractor used to identify words in the document. Segmenter used to split page into blocks. Scale multiplier to apply to output document, defaults to 1. Character to use for indentation, defaults to tab. How to handle invalid characters.

Alto 4.1 (XML). See https://github.com/altoxml/schema

Get the Alto (XML) string of the pages layout.

The document to extract page layouts from. Draw PdfPaths present in the page.

Get the Alto (XML) string of the page layout. Excludes s.

The page to export the XML layout for.

Get the Alto (XML) string of the page layout.

The page to export the XML layout for. Whether the output should include the PdfPaths present in the page.

Create an empty .

Deserialize an from a given Alto format XML document.

[Alto] Alto Schema root Version 4.1 See https://github.com/altoxml/schema

[Alto] Alternative.

Purpose.

Value.

[Alto] Base type for any kind of block on the page.

The rotation of e.g. text or illustration within the block. The value is in degree counterclockwise.

The next block in reading sequence on the page.

Correction Status. Indicates whether manual correction has been done or not. The correction status should be recorded at the highest level possible (Block, TextLine, String).

[Alto/xlink] Block Type Actuate

[Alto/xlink] Block Type Show.

[Alto] A circle shape. and describe the center of the circle.

[Alto] A block that consists of other blocks. WARNING: The CIRCULAR GROUP REFERENCES was removed from the xsd. NEED TO ADD IT BACK!!!

A user defined string to identify the type of composed block (e.g. table, advertisement, ...)

An ID to link to an image which contains only the composed block. The ID and the file link is defined in the related METS file.

[Alto] Description

Element deprecated. 'Processing' should be used instead.

[Alto] Description Ocr Processing Element deprecated. 'AltoProcessing' should be used instead.

[Alto] Description Processing

Id.

[Alto] A unique identifier for the document. This identifier must be unique within the local To facilitate file sharing or interoperability with other systems, documentIdentifierLocation may be added to designate the system or application where the identifier is unique.

A location qualifier, i.e., a namespace.

[Alto] An ellipse shape. HPOS and VPOS describe the center of the ellipse. HLENGTH and VLENGTH are the width and height of the described ellipse. The attribute ROTATION tells the rotation of the e.g. text or illustration within the block.The value is in degrees counterclockwise.

[Alto] A unique identifier for the image file. This is drawn from MIX. This identifier must be unique within the local To facilitate file sharing or interoperability with other systems, fileIdentifierLocation may be added to designate the system or application where the identifier is unique.

[Alto] Font styles.

Bold.

Italics.

Subscript.

Superscript.

Small caps.

Underline.

[Alto] Font type (Serif or Sans-Serif).

Serif.

Sans-serif.

[Alto] Font width (Fixed or proportional).

Proportional.

Remarks.

[Alto] Modern OCR software stores information on glyph level. A glyph is essentially a character or ligature. Accordingly the value for the glyph element will be defined as follows: Pre-composed representation = base + combining character(s) (decomposed representation) See http://www.fileformat.info/info/unicode/char/0101/index.htm "U+0101" = (U+0061) + (U+0304) "combining characters" ("base characters" in combination with non-spacing marks or characters which are combined to one) are represented as one "glyph", e.g.áàâ. Each glyph has its own coordinate information and must be separately addressable as a distinct object. Correction and verification processes can be carried out for individual characters. Post-OCR analysis of the text as well as adaptive OCR algorithm must be able to record information on glyph level. In order to reproduce the decision of the OCR software, optional characters must be recorded.These are called variants. The OCR software evaluates each variant and picks the one with the highest confidence score as the glyph. The confidence score expresses how confident the OCR software is that a single glyph had been recognized correctly. The glyph elements are in order of the word. Each glyph need to be recorded to built up the whole word sequence. The glyph’s CONTENT attribute is no replacement for the string’s CONTENT attribute. Due to post-processing steps such as correction the values of both attributes may be inconsistent.

Alternative (combined) character for the glyph, outlined by OCR engine or similar recognition processes. In case the variant are two (combining) characters, two characters are outlined in one Variant element. E.g. a Glyph element with CONTENT="m" can have a Variant element with the content "rn". Details for different use-cases see on the samples on GitHub.

CONTENT contains the precomposed representation (combining character) of the character from the parent String element. The sequence position of the Gylph element matches the position of the character in the String.

This GC attribute records a float value between 0.0 and 1.0 that expresses the level of confidence for the variant where is 1 is certain. This attribute is optional. If it is not available, the default value for the variant is "0". The GC attribute semantic is the same as the WC attribute on the String element and VC on Variant element.

[Alto] A graphic used to separate blocks. Usually a line or rectangle.

[Alto] A picture or image.

A user defined string to identify the type of illustration like photo, map, drawing, chart, ...

A link to an image which contains only the illustration.

[Alto] There are following variation of tag types available: LayoutTag – criteria about arrangement or graphical appearance; StructureTag – criteria about grouping or formation; RoleTag – criteria about function or mission; NamedEntityTag – criteria about assignment of terms to their relationship / meaning (NER); OtherTag – criteria about any other characteristic not listed above, the TYPE attribute is intended to be used for classification within those.;

Criteria about arrangement or graphical appearance.

Criteria about assignment of terms to their relationship / meaning (NER).

Criteria about any other characteristic not listed above, the TYPE attribute is intended to be used for classification within those.

Criteria about function or mission.

Criteria about grouping or formation.

[Alto] Layout.

[Alto] All measurement values inside the alto file are related to this unit, except the font size. Coordinates as being used in HPOS and VPOS are absolute coordinates referring to the upper-left corner of a page. The upper left corner of the page is defined as coordinate (0/0). values meaning: mm10: 1/10th of millimeter; inch1200: 1/1200th of inch; pixel: 1 pixel The values for pixel will be related to the resolution of the image based on which the layout is described. Incase the original image is not known the scaling factor can be calculated based on total width and height of the image and the according information of the PAGE element.

1 pixel.

1/10th of millimeter.

1/1200th of inch.

[Alto] Ocr Processing Element deprecated. 'AltoProcessing' should be used instead.

[Alto] One page of a document.

The area between the top line of print and the upper edge of the leaf. It may contain page number or running title.

The area between the printspace and the left border of a page. May contain margin notes.

The area between the printspace and the right border of a page. May contain margin notes.

The area between the bottom line of letterpress or writing and the bottom edge of the leaf. It may contain a page number, a signature number or a catch word.

Rectangle covering the printed area of a page. Page number and running title are not part of the print space.

Any user-defined class like title page.

The number of the page within the document.

The page number that is printed on the page.

A link to the processing description that has been used for this page.

Estimated percentage of OCR Accuracy in range from 0 to 100

[Alto] A region on a page.

Shape.

[Alto] A paragraph style defines formatting properties of text blocks.

Indicates the alignement of the paragraph. Could be left, right, center or justify.

Left indent of the paragraph in relation to the column.

Right indent of the paragraph in relation to the column.

Line spacing between two lines of the paragraph. Measurement calculated from baseline to baseline.

Indent of the first line of the paragraph if this is different from the other lines. A negative value indicates an indent to the left, a positive value indicates an indent to the right.

[Alto] Indicates the alignment of the paragraph. Could be left, right, center or justify.

[Alto] A polygon shape.

[Alto] Position of the page. Could be lefthanded, righthanded, cover, foldout or single if it has no special position.

Left page.

Right page.

Foldout page.

Single page.

Cover page.

Encapsulates width/height and position data.

Height.

Whether to include in the output.

Width.

Whether to include in the output.

Horizontal position.

Whether to include in the output.

Vertical position.

Whether to include in the output.

[Alto] Classification of the category of operation, how the file was created, including generation, modification, preprocessing, postprocessing or any other steps.

Content generation.

Content modification.

Pre-operation.

Post-operation.

Other.

[Alto] Information about a software application. Where applicable, the preferred method for determining this information is by selecting Help -- About.

The name of the organization or company that created the application.

The name of the application.

The version of the application.

A description of any important characteristics of the application, especially for non-commercial applications. For example, if a non-commercial application is built using commercial components, e.g., an OCR engine SDK. Those components should be mentioned here.

[Alto] Description of the processing step.

Classification of the category of operation, how the file was created, including generation, modification, preprocessing, postprocessing or any other steps.

Date or DateTime the image was processed.

Identifies the organization level producer(s) of the processed image.

An ordinal listing of the image processing steps performed. For example, "image despeckling."

A description of any setting of the processing application. For example, for a multi-engine OCR application this might include the engines which were used. Ideally, this description should be adequate so that someone else using the same application can produce identical results.

[Alto] Gives brief information about original page quality

[Alto] Describes the bounding shape of a block, if it is not rectangular.

[Alto] Information to identify the image file from which the OCR text was created.

[Alto] A white space.

[Alto] A sequence of chars. Strings are separated by white spaces or hyphenation chars.

Content of the substitution.

Confidence level of each character in that string. A list of numbers, one number between 0 (sure) and 9 (unsure) for each character.

Correction Status. Indicates whether manual correction has been done or not. The correction status should be recorded at the highest level possible (Block, TextLine, String).

Attribute to record language of the string. The language should be recorded at the highest level possible.

[Alto] Styles.

Text Style.

Paragraph Style.

[Alto] Type of the substitution (if any).

[Alto] Tag.

The xml data wrapper element XmlData is used to contain XML encoded metadata. The content of an XmlData element can be in any namespace or in no namespace. As permitted by the XML Schema Standard, the processContents attribute value for the metadata in an XmlData is set to "lax". Therefore, if the source schema and its location are identified by means of an XML schemaLocation attribute, then an XML processor will validate the elements for which it can find declarations.If a source schema is not identified, or cannot be found at the specified schemaLocation, then an XML validator will check for well-formedness, but otherwise skip over the elements appearing in the XmlData element.

Type can be used to classify and group the information within each tag element type.

Content / information value of the tag.

Description text for tag information for clarification.

Any URI for authority or description relevant information.

[Alto] The xml data wrapper element XmlData is used to contain XML encoded metadata. The content of an XmlData element can be in any namespace or in no namespace. As permitted by the XML Schema Standard, the processContents attribute value for the metadata in an XmlData is set to "lax". Therefore, if the source schema and its location are identified by means of an XML schemaLocation attribute, then an XML processor will validate the elements for which it can find declarations. If a source schema is not identified, or cannot be found at the specified schemaLocation, then an XML validator will check for well-formedness, but otherwise skip over the elements appearing in the XmlData element.

[Alto] A block of text.

Attribute deprecated. LANG should be used instead.

Attribute to record language of the textblock.

[Alto] A single line of text.

A hyphenation char. Can appear only at the end of a line.

Correction Status. Indicates whether manual correction has been done or not. The correction status should be recorded at the highest level possible (Block, TextLine, String).

[Alto] A hyphenation char. Can appear only at the end of a line.

Content.

[Alto] A text style defines font properties of text.

The font name.

The font size, in points (1/72 of an inch).

The font color as an RGB value.

The font style.

[Alto] Alternative (combined) character for the glyph, outlined by OCR engine or similar recognition processes. In case the variant are two (combining) characters, two characters are outlined in one Variant element. E.g. a Glyph element with CONTENT="m" can have a Variant element with the content "rn". Details for different use-cases see on the samples on GitHub.

Each Variant represents an option for the glyph that the OCR software detected as possible alternatives. In case the variant are two(combining) characters, two characters are outlined in one Variant element. E.g.a Glyph element with CONTENT="m" can have a Variant element with the content "rn". Details for different use-cases see on the samples on GitHub.

This VC attribute records a float value between 0.0 and 1.0 that expresses the level of confidence for the variant where is 1 is certain. This attribute is optional. If it is not available, the default value for the variant is "0". The VC attribute semantic is the same as the GC attribute on the Glyph element.

Describes general settings of the alto file like measurement units and metadata

Styles define properties of layout elements. A style defined in a parent element is used as default style for all related children elements.

Tag define properties of additional characteristic. The tags are referenced from related content element on Block or String element by attribute TAGREF via the tag ID. This container element contains the individual elements for LayoutTags, StructureTags, RoleTags, NamedEntityTags and OtherTags

The root layout element.

Schema version of the ALTO file.

hOCR v1.2 (HTML) text exporter. See http://kba.cloud/hocr-spec/1.2/

hOCR v1.2 (HTML) See http://kba.cloud/hocr-spec/1.2/

Get the hOCR (HTML) string of the page layout.

The document. Draw PdfPaths present in the page. Will add a reference to the 'hocrjs' script just before the closing 'body' tag, adding the interface to a plain hOCR file.See https://github.com/kba/hocrjs for more information.

Get the hOCR (HTML) string of the page layout. Excludes PdfPaths.

The page.

Get the hOCR (HTML) string of the page layout.

The page. Draw PdfPaths present in the page. The image name, if any. Will add a reference to the 'hocrjs' script just before the closing 'body' tag, adding the interface to a plain hOCR file.See https://github.com/kba/hocrjs for more information.

Get indent string from level.

The indent level.

Get the hOCR string for the page. http://kba.cloud/hocr-spec/1.2/#elementdef-ocr_page

Draw PdfPaths present in the page.

Get the hOCR string for the path. http://kba.cloud/hocr-spec/1.2/#elementdef-ocr_linedrawing

The indent level.

Get the hOCR string for the area. http://kba.cloud/hocr-spec/1.2/#elementdef-ocr_carea

The text area. The indent level.

Get the hOCR string for the paragraph. See http://kba.cloud/hocr-spec/1.2/#elementdef-ocr_par

The paragraph. The indent level.

Get the hOCR string for the text line. See http://kba.cloud/hocr-spec/1.2/#elementdef-ocr_line

The indent level.

Get the hOCR string for the word. See http://kba.cloud/hocr-spec/1.2/#elementdef-ocrx_word

The indent level.

Get the hOCR string for the bounding box. See http://kba.cloud/hocr-spec/1.2/#propdef-bbox

How to handle invalid characters.

Custom strategy.

Do not check invalid character.

Remove invalid character.

Convert invalid character to hexadecimal representation.

Exports the page's text into the desired format.

Get the text representation of a page in a desired format.

The page to convert to the format. The containing the page contents represented in a compatible format.

PAGE-XML 2019-07-15 (XML) text exporter. See https://github.com/PRImA-Research-Lab/PAGE-XML

Indent character. How to handle invalid characters.

PAGE-XML 2019-07-15 (XML) text exporter. See https://github.com/PRImA-Research-Lab/PAGE-XML

Indent character. How to handle invalid characters.

Get the PAGE-XML (XML) string of the pages layout. Not implemented, use instead.

Draw PdfPaths present in the page.

Get the PAGE-XML (XML) string of the pages layout. Excludes PdfPaths.

Get the PAGE-XML (XML) string of the pages layout.

Draw PdfPaths present in the page.

Converts a point to a string

The width of the page where the pdf point is located on The height of the page where the pdf point is located on

PageXml Text colour in RGB encoded format (red value) + (256 x green value) + (65536 x blue value).

Deserialize an from a given PAGE format XML document.

Class to keep track of a page data.

PAGE (Page Analysis and Ground-Truth Elements) root Version 2019-07-15

Regions containing advertisements.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). Range: -179.999,180

The background colour of the region

Confidence value (between 0 and 1)

Border of the actual page (if the scanned image contains parts not belonging to the page).

Regions containing charts or graphs of any type, should be marked as chart regions.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). Range: -179.999,180

The type of chart in the region

An approximation of the number of colours used in the region

The background colour of the region

Specifies whether the region also contains text

Regions containing chemical formulas.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew(negative values indicate anti-clockwise rotation). Range: -179.999,180

The background colour of the region

Polygon outline of the element as a path of points. No points may lie outside the outline of its parent, which in the case of Border is the bounding rectangle of the root image. Paths are closed by convention, i.e.the last point logically connects with the first (and at least 3 points are required to span an area). Paths must be planar (i.e.must not self-intersect).

Confidence value (between 0 and 1)

Regions containing content that is not covered by the default types(text, graphic, image, line drawing, chart, table, separator, maths, map, music, chem, advert, noise, unknown).

Information on the type of content represented by this region

Alternative glyph images (e.g. black-and-white)

Container for graphemes, grapheme groups and non-printing characters

Semantic labels / tags

The script used for the glyph

Overrides the production attribute of the parent word / text line / text region.

For generic use

Represents a sub-element of a glyph. Smallest graphical unit that can be assigned a Unicode code point.

Base type for graphemes, grapheme groups and non-printing characters.

Order index of grapheme, group, or non-printing character within the parent container (graphemes or glyph or grapheme group).

Type of character represented by the grapheme, group, or non-printing character element.

For generic use

Regions containing simple graphics, such as a company logo, should be marked as graphic regions.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). Range: -179.999,180

The type of graphic in the region

An approximation of the number of colours used in the region

Specifies whether the region also contains text.

Points with x,y coordinates.

The grid row index

An image is considered to be more intricate and complex than a graphic. These can be photos or drawings.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). Range: -179.999,180

The colour bit depth required for the region

The background colour of the region

Specifies whether the region also contains text

Semantic label

The label / tag (e.g. 'person'). Can be an RDF resource identifier (e.g. object of an RDF triple).

Additional information on the label (e.g. 'YYYY-mm-dd' for a date label). Can be used as predicate of an RDF triple.

A semantic label / tag

Reference to external model / ontology / schema

E.g. an RDF resource identifier (to be used as subject or object of an RDF triple)

Prefix for all labels (e.g. first part of an URI)

ISO 639.x 2016-07-14

Can be used to express the z-index of overlapping regions.An element with a greater z-index is always in front of another element with lower z-index.

A line drawing is a single colour illustration without solid areas.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). Range: -179.999,180

The pen (foreground) colour of the region

The background colour of the region

Specifies whether the region also contains text

Regions containing maps.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew(negative values indicate anti-clockwise rotation). Range: -179.999,180

Regions containing equations and mathematical symbols should be marked as maths regions.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). Range: -179.999,180

The background colour of the region

The timestamp has to be in UTC (Coordinated Universal Time) and not local time.

External reference of any kind

Semantic labels / tags

Type of metadata (e.g. author)

E.g. imagePhotometricInterpretation

E.g. RGB

Regions containing musical notations.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). Range: -179.999,180

The background colour of the region

Noise regions are regions where no real data lies, only false data created by artifacts on the document or scanner noise.

A glyph component without visual representation but with Unicode code point. Non-visual / non-printing / control character. Part of grapheme container (of glyph) or grapheme sub group.

Numbered group (contains ordered elements)

Semantic labels / tags

Optional link to a parent region of nested regions. The parent region doubles as reading order group. Only the nested regions should be allowed as group members.

Is this group a continuation of another group (from previous column or page, for example)?

For generic use

Alternative document page images (e.g.black-and-white).

Order of blocks within the page.

Unassigned regions are considered to be in the (virtual) default layer which is to be treated as below any other layers.

Default text style

Semantic labels / tags

Contains the image file name including the file extension.

Specifies the width of the image.

Specifies the height of the image.

Specifies the image resolution in width.

Specifies the image resolution in height.

Specifies the unit of the resolution information referring to a standardised unit of measurement (pixels per inch, pixels per centimeter or other).

For generic use

The angle the rectangle encapsulating the page (or its Border) has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). (The rotated image can be further referenced via “AlternativeImage”.) Range: -179.999, 180

The type of the page within the document (e.g.cover page).

The primary language used in the page (lower-level definitions override the page-level definition).

The secondary language used in the page (lower-level definitions override the page-level definition).

The primary script used in the page (lower-level definitions override the page-level definition).

The secondary script used in the page (lower-level definitions override the page-level definition).

The direction in which text within lines should be read(order of words and characters), in addition to “textLineOrder” (lower-level definitions override the page-level definition).

The order of text lines within a block, in addition to “readingDirection” (lower-level definitions override the page-level definition).

Confidence value for whole page (between 0 and 1)

Specifies the unit of the resolution information referring to a standardised unit of measurement (pixels per inch, pixels per centimeter or other).

Determines the effective area on the paper of a printed page. Its size is equal for all pages of a book (exceptions: titlepage, multipage pictures). It contains all living elements (except marginals) like body type, footnotes, headings, running titles. It does not contain pagenumber (if not part of running title), marginals, signature mark, preview words.

Text production type

Confidence value (between 0 and 1)

Alternative region images (e.g.black-and-white).

Semantic labels / tags

Roles the region takes (e.g. in context of a parent region).

For generic use

Is this region a continuation of another region (in previous column or page, for example)?

Numbered region

Position (order number) of this item within the current hierarchy level.

One-to-one relation between to layout object. Use 'link' for loose relations and 'join' for strong relations (where something is fragmented for instance). Examples for 'link': caption - image floating - paragraph paragraph - paragraph (when a paragraph is split across columns and the last word of the first paragraph DOES NOT continue in the second paragraph) drop-cap - paragraph (when the drop-cap is a whole word) Examples for 'join': word - word (separated word at the end of a line) drop-cap - paragraph (when the drop-cap is not a whole word) paragraph - paragraph (when a pragraph is split across columns and the last word of the first paragraph DOES continue in the second paragraph)

Semantic labels / tags

For generic use

Container for one-to-one relations between layout objects (for example: DropCap - paragraph, caption - image).

Data for a region that takes on the role of a table cell within a parent table region.

iso15924 2016-07-14

Separators are lines that lie between columns and paragraphs and can be used to logically separate different articles from each other.

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). Range: -179.999,180

The colour of the separator

Data for a region that takes on the role of a table cell within a parent table region.

Cell position in table starting with row 0

Cell position in table starting with column 0

Number of rows the cell spans (optional; default is 1)

Number of columns the cell spans (optional; default is 1)

Is the cell a column or row header?

Tabular data in any form is represented with a table region.Rows and columns may or may not have separator lines; these lines are not separator regions.

Table grid (visible or virtual grid lines)

The angle the rectangle encapsulating a region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). Range: -179.999,180

The number of rows present in the table

The number of columns present in the table

The colour of the lines used in the region

The background colour of the region

Specifies the presence of line separators

Specifies whether the region also contains text

Examples: "123.456", "+1234.456", "-1234.456", "-.456", "-456"

Examples: "123.456", "+1234.456", "-1.2344e56", "-.45E-6", "INF", "-INF", "NaN"

Examples: "123456", "+00000012", "-1", "-456"

Examples: "true", "false", "1", "0"

Examples: "2001-10-26", "2001-10-26+02:00", "2001-10-26Z", "2001-10-26+00:00", "-2001-10-26", "-20000-04-01"

Examples: "21:32:52", "21:32:52+02:00", "19:32:52Z", "19:32:52+00:00", "21:32:52.12679"

Examples: "2001-10-26T21:32:52", "2001-10-26T21:32:52+02:00", "2001-10-26T19:32:52Z", "2001-10-26T19:32:52+00:00","-2001-10-26T21:32:52", "2001-10-26T21:32:52.12679"

Generic text string

An XSD type that is not listed or a custom type (use dataTypeDetails attribute).

Text in a "simple" form (ASCII or extended ASCII as mostly used for typing). I.e.no use of special characters for ligatures (should be stored as two separate characters) etc.

Correct encoding of the original, always using the corresponding Unicode code point. I.e. ligatures have to be represented as one character etc.

Used for sort order in case multiple TextEquivs are defined. The text content with the lowest index should be interpreted as the main text content.

Type of text content (is it free text or a number, for instance). This is only a descriptive attribute, the text type is not checked during XML validation.

Refinement for dataType attribute. Can be a regular expression, for instance.

Alternative text line images (e.g. black-and-white)

Multiple connected points that mark the baseline of the glyphs

Semantic labels / tags

Pure text is represented as a text region. This includes drop capitals, but practically ornate text may be considered as a graphic.

The angle the rectangle encapsulating the region has to be rotated in clockwise direction in order to correct the present skew (negative values indicate anti-clockwise rotation). (The rotated image can be further referenced via “AlternativeImage”.) Range: -179.999,180

The nature of the text in the region

The degree of space in points between the lines of text(line spacing)

The direction in which text within lines should be read(order of words and characters), in addition to “textLineOrder”.

The order of text lines within the block, in addition to “readingDirection”.

The angle the baseline of text within the region has to be rotated(relative to the rectangle encapsulating the region) in clockwise direction in order to correct the present skew, in addition to “orientation” (negative values indicate anti-clockwise rotation). Range: -179.999,180

Defines whether a region of text is indented or not

Text align

The primary language used in the region

The secondary language used in the region

The primary script used in the region

The secondary script used in the region

Paragraph

Heading

Caption

Header

Footer

Page number

Drop Capital, a letter a the beginning of a word that is bigger than the usual character size. Usually to start a chapter.

Credit

Floating

Signature mark

Catch word

Marginalia

Foot note

Foot note - continued

End note

Table of content

List

Other

Monospace (fixed-pitch, non-proportional) or proportional font.

For instance: Arial, Times New Roman. Add more information if necessary (e.g.blackletter, antiqua).

Serif or sans-serif typeface.

The size of the characters in points.

The x-height or corpus size refers to the distance between the baseline and the mean line of lower-case letters in a typeface. The unit is assumed to be pixels.

The degree of space (in points) between the characters in a string of text.

Text colour in RGB encoded format (red value) + (256 x green value) + (65536 x blue value).

Background colour

Background colour in RGB encoded format (red value) + (256 x green value) + (65536 x blue value).

Specifies whether the colour of the text appears reversed against a background colour.

Line style details if "underlined" is TRUE

To be used if the region type cannot be ascertained.

Numbered group (contains unordered elements)

Semantic labels / tags

Optional link to a parent region of nested regions. The parent region doubles as reading order group. Only the nested regions should be allowed as group members.

Is this group a continuation of another group (from previous column or page, for example)?

For generic use

Indexed group containing ordered elements

Semantic labels / tags

Optional link to a parent region of nested regions. The parent region doubles as reading order group. Only the nested regions should be allowed as group members.

Position (order number) of this item within the current hierarchy level.

Is this group a continuation of another group (from previous column or page, for example)?

For generic use

Structured custom data defined by name, type and value.

Alternative word images (e.g. black-and-white)

Semantic labels / tags

Overrides primaryLanguage attribute of parent line and/or text region

The primary script used in the word

The secondary script used in the word

The direction in which text within the word should be read(order of characters).

Overrides the production attribute of the parent text line and/or text region.

For generic use

Exports a page as an SVG.

Used to round numbers.

Not in use.

Svg text exporter.

How to handle invalid characters.

Svg text exporter.

How to handle invalid characters.

Get the page contents as an SVG.

Interface that stores options that configure the operation of methods of the document layout analysis algorithm.

Gets or sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

K-D tree data structure of .

The points used to build the tree.

Get the nearest neighbour to the pivot point. Only returns 1 neighbour, even if equidistant points are found.

The point for which to find the nearest neighbour. The distance measure used, e.g. the Euclidian distance. The nearest neighbour's index (returns -1 if not found). The distance between the pivot and the nearest neighbour (returns if not found). The nearest neighbour's point.

Get the k nearest neighbours to the pivot point. Might return more than k neighbours if points are equidistant. Use if only looking for the (single) closest point.

The point for which to find the nearest neighbour. The number of neighbours to return. Might return more than k neighbours if points are equidistant. The distance measure used, e.g. the Euclidian distance. Returns a list of tuples of the k nearest neighbours. Tuples are (element, index, distance).

K-D tree data structure.

The root of the tree.

Number of elements in the tree.

K-D tree data structure.

The elements used to build the tree. The function that converts the candidate elements into a .

Get the nearest neighbour to the pivot element. Only returns 1 neighbour, even if equidistant points are found.

The element for which to find the nearest neighbour. The function that converts the pivot element into a . The distance measure used, e.g. the Euclidian distance. The nearest neighbour's index (returns -1 if not found). The distance between the pivot and the nearest neighbour (returns if not found). The nearest neighbour's element.

Get the k nearest neighbours to the pivot element. Might return more than k neighbours if points are equidistant. Use if only looking for the (single) closest point.

The element for which to find the k nearest neighbours. The number of neighbours to return. Might return more than k neighbours if points are equidistant. The function that converts the pivot element into a . The distance measure used, e.g. the Euclidian distance. Returns a list of tuples of the k nearest neighbours. Tuples are (element, index, distance).

K-D tree leaf.

Return true if leaf.

K-D tree node.

Split value (X or Y axis).

Split point.

Left child.

Right child.

The node's element.

True if this cuts with X axis, false if cuts with Y axis.

The element's depth in the tree.

Return true if leaf.

The index of the element in the original array.

Get the leaves.

Useful math extensions.

Computes the mode of a sequence of values.

The sequence of floats. The mode of the sequence. Returns if the sequence has no mode or if it is not unique.

Computes the mode of a sequence of values.

The sequence of doubles. The mode of the sequence. Returns if the sequence has no mode or if it is not unique.

Test for almost equality to 0.

Test for almost equality.

Default Page Segmenter. All words are included in one block.

Create an instance of default page segmenter, .

using default options values.

Create using options values.

The to use.

Get the text blocks using options.

The page's words to generate text blocks for. The s generated by the default method.

Default page segmenter options.

Default value is -1.

Default value is ' ' (space).

Default value is '\n' (new line).

The Document Spectrum (Docstrum) algorithm is a bottom-up page segmentation technique based on nearest-neighbourhood clustering of connected components extracted from the document. This implementation leverages bounding boxes and does not exactly replicates the original algorithm. See 'The document spectrum for page layout analysis.' by L. O'Gorman.

Create an instance of Docstrum for bounding boxes page segmenter, .

Create an instance of Docstrum for bounding boxes page segmenter using default options values.

Create an instance of Docstrum for bounding boxes page segmenter using options values.

The to use.

Get the blocks.

The page's words to segment into s. The s generated by the document spectrum method.

Get the blocks. See original paper for more information.

The words to segment into s. Angle bounds for words to be considered as neighbours on the same line. Multiplier that gives the maximum euclidian distance between words for building lines. Maximum distance will be this number times the within-line distance found by the analysis. The bin size used when building the within-line distances distribution. Angle bounds for words to be considered as neighbours on separate lines. Multiplier that gives the maximum perpendicular distance between text lines for blocking. Maximum distance will be this number times the between-line distance found by the analysis. The bin size used when building the between-line distances distribution. The angular difference bounds between two lines to be considered in the same block. This defines if two lines are parallel enough. Precision when testing equalities. Separator used between words when building lines. Separator used between lines when building paragraphs. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations. The s generated by the document spectrum method.

Estimation of within-line and between-line spacing. This is the Docstrum algorithm's 1st step.

The list of words. Angle bounds for words to be considered as neighbours on the same line. The bin size used when building the within-line distances distribution. Angle bounds for words to be considered as neighbours on separate lines. The bin size used when building the between-line distances distribution. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations. The estimated within-line distance. Computed as the average peak value of distribution. The estimated between-line distance. Computed as the average peak value of distribution. False if either 'withinLineDistance' or 'betweenLineDistance' is .

Get the average distance value of the peak bucket of the histogram.

The set of distances to average.

Get the s by grouping words using nearest neighbours. This is the Docstrum algorithm's 2nd step.

The words to segment into s. The maximum within-line distance. Computed as the estimated within-line spacing times the within-line multiplier in the default implementation. Angle bounds for words to be considered as neighbours on the same line. Separator used between words when building lines. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations. The s built.

Helper function to compute the within line angle between the pivot's bottom right and the candidate's bottom left points, taking in account the pivot's rotation. -90 ≤ θ ≤ 90.

Get the s. This is the Docstrum algorithm's 3rd and final step. Method: We want to measure the distance between two lines using the following method:
- We check if two lines are overlapping horizontally and compute the perpendicular distance.

- We check if the angle between the two line is within 'angularDifference'.

- If the two lines are not overlapping or the angle is too wide, the distance is set to the infinity.
If two text lines are approximately parallel, close in perpendicular distance, and they either overlap to some specified degree or are separated by only a small distance in parallel distance, then they are said to meet the criteria to belong to the same structural block.

The lines to segment into s. The maximum between-line distance. Computed as the estimated between-line spacing times the between-line multiplier in the default implementation. The angular difference bounds between two lines to be considered in the same block. This defines if two lines are parallel enough. Precision when testing equalities. Separator used between lines when building paragraphs. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations. The s built.

Perpendicular overlapping distance.

Get the structural blocking parameters.

The angle between the 2 lines.-180 ≤ θ ≤ 180 Overlap of segment i onto j. Positive value if overlapped, negative value if nonoverlapped.[-1, 1]? Signed perpendicular distance. Return true if overlapped, false if nonoverlapped.

Helper function to check if the point belongs to the line./>

Line's first point. Line's second point. The point to check.

Helper function to check if 2 lines are equal.

Helper function to compute the between line angle between the pivot's and the candidate's centroid points, taking in account the pivot's rotation. 0 ≤ θ ≤ 180.

The bounds for the angle between two words for them to have a certain type of relationship.

The lower bound in degrees.

The upper bound in degrees.

Create a new .

Whether the bounds contain the angle.

Docstrum bounding boxes page segmenter options.

Default value is -1.

Default value is ' ' (space).

Default value is '\n' (new line).

Precision when testing equalities. Default value is 1e-3.

Angle bounds for words to be considered as neighbours on the same line. Default value is -30 ≤ θ ≤ 30.

Multiplier that gives the maximum euclidean distance between words for building lines. Maximum distance will be this number times the within-line distance found by the analysis. Default value is 3.

The bin size used when building the within-line distances distribution. Default value is 10.

Angle bounds for words to be considered as neighbours on separate lines. Default value is 45 ≤ θ ≤ 135.

Multiplier that gives the maximum perpendicular distance between text lines for blocking. Maximum distance will be this number times the between-line distance found by the analysis. Default value is 1.3.

The bin size used when building the between-line distances distribution. Default value is 10.

The angular difference bounds between two lines to be considered in the same block. This defines if two lines are parallel enough. Default value is -30 ≤ θ ≤ 30.

Page segmentation divides a page into areas, each consisting of a layout structure (blocks, lines, etc.). See 'Performance Comparison of Six Algorithms for Page Segmentation' by Faisal Shafait, Daniel Keysers, and Thomas M. Breuel.

Get the blocks.

The page's words to generate text blocks for. A list of text blocks from this approach.

Page segmenter options interface.

Separator used between words when building lines.

Separator used between lines when building paragraphs.

The recursive X-Y cut is a top-down page segmentation technique that decomposes a document recursively into a set of rectangular blocks. This implementation leverages bounding boxes. https://en.wikipedia.org/wiki/Recursive_X-Y_cut See 'Recursive X-Y Cut using Bounding Boxes of Connected Components' by Jaekyu Ha, Robert M.Haralick and Ihsin T. Phillips

Create an instance of Recursive X-Y Cut page segmenter, .

Create an instance of Recursive X-Y Cut page segmenter using default options values.

Create an instance of Recursive X-Y Cut page segmenter using options values.

The to use.

Get the blocks.

The page's words to segment into s. The s generated by the Recursive X-Y cut method.

Get the blocks.

The words in the page. The minimum width for a block. The function that determines the dominant font width. The function that determines the dominant font height.

Returns true if the value is greater or equal to the lower bound and smaller or equal to the upper bound.

The value to test.

Recursive X-Y cut page segmenter options.

Default value is -1.

Default value is ' ' (space).

Default value is '\n' (new line).

The minimum width for a block. Default value is 1.

The function that determines the dominant font width. Default value is the mode of the block's letters width. If the mode is not available, the average is used.

The function that determines the dominant font height. Default value is the mode of the block's letters height times 1.5. If the mode is not available, the average is used.

A Leaf node used in the algorithm, i.e. a block.

Returns true if this node is a leaf, false otherwise.

The words in the leaf.

The number of words in the leaf.

Returns null as a leaf doesn't have leaves.

Gets the lines of the leaf.

Create a new .

The words contained in the leaf.

Create a new .

The words contained in the leaf.

A Node used in the algorithm.

Returns true if this node is a leaf, false otherwise.

The rectangle completely containing the node.

The children of the node.

Create a new .

The node's children.

Create a new .

The node's children.

Recursively counts the words included in this node.

Recursively gets the leaves (last nodes) of this node.

This detector does nothing, no ordering takes place.

Create an instance of default reading order detector, . This detector does nothing, no ordering takes place.

Gets the blocks in reading order and sets the .

The s to order.

Gets the Thick Boundary Rectangle Relations (TBRR) The Thick Boundary Rectangle Relations (TBRR) is a set of qualitative relations representing the spatial relations of the document objects on the page. For every pair of document objects a and b, one X and one Y interval relation hold. If one considers the pair in reversed order, the inverse interval relation holds. Therefore the directed graph g_i representing these relations is complete. See also https://en.wikipedia.org/wiki/Allen%27s_interval_algebra

Gets the Thick Boundary Rectangle Relations (TBRR) for the X coordinate. The Thick Boundary Rectangle Relations (TBRR) is a set of qualitative relations representing the spatial relations of the document objects on the page. For every pair of document objects a and b, one X and one Y interval relation hold. If one considers the pair in reversed order, the inverse interval relation holds. Therefore the directed graph g_i representing these relations is complete.

The tolerance parameter T. If two coordinates are closer than T they are considered equal.

Gets the Thick Boundary Rectangle Relations (TBRR) for the Y coordinate. The Thick Boundary Rectangle Relations (TBRR) is a set of qualitative relations representing the spatial relations of the document objects on the page. For every pair of document objects a and b, one X and one Y interval relation hold. If one considers the pair in reversed order, the inverse interval relation holds. Therefore the directed graph g_i representing these relations is complete.

The tolerance parameter T. If two coordinates are closer than T they are considered equal.

Allen’s interval thirteen relations. See https://en.wikipedia.org/wiki/Allen%27s_interval_algebra

Unknown interval relations.

X takes place before Y. |____X____|---------------------- ----------------------|____Y____|

X meets Y. |_____X______|-------------- --------------|______Y_____|

X overlaps with Y. |________X________|------------- -------------|________Y________|

X starts Y. |____X____|----------------- |_______Y_______|-----------

X during Y. --------|____X____|--------- -----|_______Y________|-----

X finishes Y. -----------------|____X____| -----------|_______Y_______|

Inverse precedes.

Inverse meets.

Inverse overlaps.

Inverse Starts.

Inverse during.

Inverse finishes.

X is equal to Y. ----------|____X____|------------ ----------|____Y____|------------

Reading order detector determines the page's blocks reading order. Note: Make sure you use to set each reading order when implementing .

Gets the blocks in reading order and sets the .

The s to order.

Helper functions for words and lines ordering.

Order words by reading order in a line. Assumes LtR and accounts for rotation.

Order lines by reading order in a block. Assumes TtB and accounts for rotation.

Algorithm that retrieve the blocks' reading order using rendering order (TextSequence).

Create an instance of rendering reading order detector, . This detector uses the rendering order (TextSequence).

Gets the blocks in reading order and sets the .

The s to order.

Algorithm that retrieve the blocks' reading order using spatial reasoning (Allen’s interval relations) and possibly the rendering order (TextSequence). See section 4.1 of 'Unsupervised document structure analysis of digital scientific articles' by S. Klampfl, M. Granitzer, K. Jack, R. Kern and 'Document Understanding for a Broad Class of Documents' by L. Todoran, M. Worring, M. Aiello and C. Monz.

The rules encoding the spatial reasoning constraints. See 'Document Understanding for a Broad Class of Documents' by L. Todoran, M. Worring, M. Aiello and C. Monz.

Basic spacial reasoning. In western culture the reading order is from left to right and from top to bottom.

Text-blocks are read in rows from left-to-right, top-to-bottom. The diagonal direction 'left-bottom to top-right' cannot be present among the Basic relations allowed.

Text-blocks are read in columns, from top-to-bottom and from left-to-right. The diagonal direction 'right-top to bottom-left' cannot be present among the Basic relations allowed.

Create an instance of unsupervised reading order detector, . This detector uses spatial reasoning (Allen’s interval relations) and possibly the rendering order (TextSequence).

Whether or not to also use the rendering order, as indicated by the TextSequence.

The rule to be used that encodes the spatial reasoning constraints.

Algorithm that retrieve the blocks' reading order using spatial reasoning (Allen’s interval relations) and possibly the rendering order (TextSequence).

The tolerance parameter T. If two coordinates are closer than T they are considered equal. This flexibility is necessary because due to the inherent noise in the PDF extraction text blocks in the same column might not be exactly aligned. The rule to be used that encodes the spatial reasoning constraints. Whether or not to also use the rendering order, as indicated by the TextSequence.

Gets the blocks in reading order and sets the .

The s to order.

Rule encoding the fact that in western culture the reading order is from left to right and from top to bottom.

The tolerance parameter T.

Column-wise: text-blocks are read in columns, from top-to-bottom and from left-to-right.

The tolerance parameter T.

Row-wise: text-blocks are read in rows from left-to-right, top- to-bottom.

The tolerance parameter T.

A block of text.

The separator used between lines in the block.

The text of the block.

The text orientation of the block.

The rectangle completely containing the block.

The text lines contained in the block.

The reading order index. Starts at 0. A value of -1 means the block is not ordered.

Create a new .

The words contained in the line, in the correct order. The separator used between lines in the block.

Sets the 's reading order.

Text edges extractor. Text edges are where words have either their BoundingBox's left, right or mid coordinates aligned on the same vertical line. Useful to detect text columns, tables, justified text, lists, etc.

Functions used to define left, middle and right edges.

Get the text edges.

The words in the page. The minimum number of elements to define a text edge. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

The type of text edge.

Text edges where words have their BoundingBox's left coordinate aligned on the same vertical line.

Text edges where words have their BoundingBox's mid coordinate aligned on the same vertical line.

Text edges where words have their BoundingBox's right coordinate aligned on the same vertical line.

Extracts text from a document based on the content order in the file.

Gets a human readable representation of the text from the page based on the letter order of the original PDF document.

A page from the document. Whether to include a double new-line when the text is likely to be a new paragraph.

Gets a human readable representation of the text from the page based on the letter order of the original PDF document.

A page from the document. Control various aspects of the generated text.

Options controlling the text generation algorithm.

Whether to include a double new-line when the text is likely to be a new paragraph. Default .

Whether to replace all whitespace characters (except line breaks) with single space ' ' character. Default .

When parsing PDF files with tables containing multiple lines in a cell or "merged" cells, the separate words can appear out of horizontal order. This option can better predict the spaces between the words. Default .

A line of text.

The separator used between words in the line.

The text of the line.

The text orientation of the line.

The rectangle completely containing the line.

The words contained in the line.

Create a new .

The words contained in the line, in the correct order. The separator used between words in the line.

A top-down algorithm that finds a cover of the background whitespace of a document in terms of maximal empty rectangles. See Section 3.2 of 'High precision text extraction from PDF documents' by Øyvind Raddum Berg and Section 2 of 'Two geometric algorithms for layout analysis' by Thomas M. Breuel.

Gets the cover of the background whitespace of a page in terms of maximal empty rectangles.

The words in the page. The images in the page. The maximum number of rectangles to find. The maximum size of the queue used in the algorithm. The identified whitespace rectangles.

Gets the cover of the background whitespace of a page in terms of maximal empty rectangles.

The words in the page. The images in the page. Lower bounds for the width of rectangles. Lower bounds for the height of rectangles. The maximum number of rectangles to find. Constant value to allow candidate whitespace rectangle to overlap the surrounding obstacles by some percent. Default value is 15%. The maximum size of the queue used in the algorithm. The identified whitespace rectangles.

Gets the cover of the background whitespace of a page in terms of maximal empty rectangles.

The list of obstacles' bounding boxes in the page. Lower bounds for the width of rectangles. Lower bounds for the height of rectangles. The maximum number of rectangles to find. Constant value to allow candidate whitespace rectangle to overlap the surrounding obstacles by some percent. Default value is 15%. The maximum size of the queue used in the algorithm. The identified whitespace rectangles.

The scoring function Q(r) which is subsequently used to sort a priority queue.

Word extractor options interface.

Nearest Neighbour Word Extractor. This implementation leverages bounding boxes.

Create an instance of Nearest Neighbour Word Extractor, .

Create an instance of Nearest Neighbour Word Extractor using default options values.

Create an instance of Nearest Neighbour Word Extractor using options values.

The to use.

Get the words.

The page's letters to group into s. The s generated by the nearest neighbour method.

Gets the words.

The letters in the page. The function that determines the maximum distance between two letters (start and end base line points), e.g. Max(GlyphRectangle.Width) x 20%. If the distance between the two letters is greater, a new word will be created. The distance measure between two letters (start and end base line points), e.g. the Manhattan distance. Function used to filter out connection between letters, e.g. check if the letters have the same color. If the function returns false, a new word will be created. Sets the maximum number of concurrent tasks enabled. A positive property value limits the number of concurrent operations to the set value. If it is -1, there is no limit on the number of concurrently running operations.

Nearest neighbour word extractor options.

Default value is -1.

The maximum distance between two letters (start and end base line points) within the same word, as a function of the two letters. If the distance between the two letters is greater than this maximum, they will belong to different words. Default value is 20% of the Max(Width, PointSize) of both letters. If is Other, this distance is doubled.

The default distance measure used between two letters (start and end base line points). Default value is the Euclidean distance.

The distance measure used between two letters (start and end base line points) with axis aligned . Only used if is set to true. Default value is the Manhattan distance.

Function used to filter out connection between letters, e.g. check if the letters have the same color. If the function returns false, letters will belong to different words. Default value checks whether the neighbour is a white space or not. If it is the case, it returns false.

Function used prior searching for the nearest neighbour. If return false, no search will be done. Default value checks whether the current letter is a white space or not. If it is the case, it returns false and no search is done.

If true, letters will be grouped by before processing. The will be used on axis aligned letters, and the on others. If false, will be used for all letters, and won't be used. Default value is true.