Method for aligning a text image to a transcription of the image

A method of operating a machine to label image locations of image regions in a text image with label data available in a transcription data structure associated with the text image;

• the machine including a processor and for memory device for storing data;
• the data stored in the memory device including instruction data the processor executes to operate the machine;
• the processor being connected to the memory device for accessing the data stored therein;
• the method comprising:
• operating the processor to store, in the memory device of the machine, an image definition data structure defining a text image including a plurality of glyphs;
• operating the processor to store, in the memory device of the machine, a transcription data structure associated with the text image and including an ordered sequence of transcription labels indicating character code information about image regions occurring in the text image;
• operating the processor to produce an ordered image region sequence of image regions occurring in the text image;
• each image region being defined with respect to its location in the text image relative to at least one glyph occurring in the text image;
• operating the processor to produce an ordered transcription region sequence of transcription regions occurring in the transcription data structure;
• each transcription region being a sequence of at least one transcription label;
• operating the processor to perform an alignment operation to align image regions in the ordered image region sequence with transcription regions in the ordered transcription region sequence;
• the alignment operation computing similarity measurements measuring a similarity between image regions and transcription regions;
• the alignment operation determining a best pairing between the image regions in the ordered image region sequence and transcription regions in the ordered transcription region sequence that optimizes the similarity measurements such that each one of the image regions in the ordered image region sequence is paired with either no (a null) transcription region or with at most one transcription region in the ordered transcription region sequence;
• and
• operating the processor to produce an image transcription alignment data structure indicating transcription regions paired with image region locations of paired image regions.

A method of operating a machine to pair image words in a two-dimensional (2D) text image with transcription words in a transcription associated with the text image;

• the machine including a processor and a memory device for storing data;
• the data stored in the memory device including instruction data the processor executes to operate the machine;
• the processor being connected to the memory device for accessing the data stored therein;
• the method comprising:
• operating the processor to receive and store, in the memory device of the machine, an image definition data structure defining a two-dimensional (2D) text image of pixels and including a plurality of glyphs;
• the 2D text image having a vertical dimension size larger than a single line;
• the plurality of glyphs representing characters in an image character set;
• operating the processor to receive and store, in the memory device of the machine, a transcription data structure associated with the 2D text image and including a plurality of transcription labels indicating character codes representing characters in the image character set;
• operating the processor to determine an image word location in the 2D text image for each of a plurality of image words occurring therein;
• each image word being an image region including at least one glyph positioned with respect to an image baseline;
• the plurality of image word locations identifying an ordered image word sequence of the image words occurring in the 2D text image;
• operating the processor to determine an image word length value for each image word in the 2D text image indicating a length of the image word;
• operating the processor to determine an image character width value indicating an estimated character width of a glyph in the 2D text image;
• operating the processor to determine a transcription word location for each of a plurality of transcription words occurring in the transcription data structure;
• each transcription word being a sequence of at least one transcription label indicating a character code in the image character set and separated from other transcription labels indicating character codes in the image character set by a transcription word boundary character code;
• the plurality of transcription word locations identifying an ordered transcription word sequence of the transcription words occurring in the transcription data structure;
• operating the processor to determine a transcription word length value for each transcription word using the image character width value and a count of the transcription labels included in the transcription word;
• operating the processor to perform an alignment operation to align transcription word lengths in the ordered transcription word sequence with image word lengths in the ordered image word sequence;
• the alignment operation maintaining the ordered image word sequence and the ordered transcription word sequence when aligning the image word lengths and the transcription word lengths;
• the alignment operation producing a list of word pairs indicating transcription words in the ordered transcription word sequence paired to matching image words in the ordered image word sequence;
• and
• operating the processor to produce an image-transcription alignment data structure using the list of word pairs, the image word locations and the transcription word locations;
• the image-transcription alignment data structure indicating, for each word pair, the transcription word location of a transcription word and the image word location of a paired image word.