Method and apparatus for font compression and decompression
AssigneeAgfa NV
InventorsAllan W. Ristow, Sampo J. Kaasila
Life of this patent
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Abstract
A font compression method and apparatus operates by: compressing different components of a font file with separate compressors having varying compression schemes to produce a plurality of intermediate compressed data sets; separating compressed glyph table components of the font file into different ones of the intermediate compressed data sets; and further compressing the intermediate compressed data sets to produce corresponding compressed output data sets. A corresponding decompression method and apparatus is used to decompress fonts which have been compressed using the above method.
Claims25
A method for font compression comprising:
- compressing different components of a font file with separate compressors having varying compression schemes to produce a plurality of intermediate compressed data sets;
- separating compressed glyph table components of said different components of the font file into different ones of said plurality of intermediate compressed data sets;
- and
- further compressing said plurality of intermediate compressed data sets to produce a corresponding plurality of compressed output data sets.
A method for producing a compressed representation of a TrueType font file comprising a table directory, and loca, cvt, hdmx, VDMX, hmtx and glyph tables, said method comprising:
- (A) compressing, with separate compressors, each of the loca, cvt, hdmx, VDMX, hmtx and a first portion of the glyph tables to produce a first intermediate compressed data set;
- (B) compressing a second portion of the glyph table to produce a second intermediate compressed data set;
- (C) compressing a third portion of the glyph table to produce a third intermediate compressed data set;
- (D) updating the font table directory;
- and,
- (E) separately compressing the first, second and third intermediate compressed data sets to produce corresponding output data sets that collectively represent the TrueType font file.
A method for font decompression comprising:
- providing a plurality of compressed output data sets each containing portions of compressed glyph table components corresponding to a font file;
- decompressing, in separate decompressors, said plurality of compressed output data sets to produce a corresponding plurality of intermediate compressed data sets;
- and
- decompressing said plurality of intermediate compressed data sets to produce said font file.
A method for producing a compressed representation of a TrueType font file at a first location and for decompressing at least a portion of the compressed representation at a second location, said method comprising:
- compressing different components of the TrueType font file, with separate compressors having different compression schemes, to produce a plurality of intermediate compressed data sets;
- further compressing the intermediate compressed data sets to produce twice compressed data sets corresponding to the plurality of intermediate compressed data sets;
- combining said twice compressed data sets into a single compressed representation of the TrueType font file at the first location;
- transmitting the compressed representation of the TrueType font file over a communications channel to the second location;
- and,
- decompressing at the second location said compressed representation of the TrueType font file to produce a decompressed output font file having functional equivalency with said TrueType font file.
A method for compressing TrueType font (TTF) data represented as a predetermined number of tables including a glyph table, the method comprising:
- generating compressed TrueType font (CTF) data by separately processing each of the tables using a different compression scheme for each table;
- moving the CTF data other than glyph table represented data into one of a multitude of CTF data groups;
- transferring and distributing the CTF data representing the glyph table into the multitude of CTF data groups;
- producing compressed data sets by separately processing each CTF data group;
- and
- providing final compressed TrueType font data by combining the compressed data sets.
A system for compressing TrueType font (TTF) data represented as a predetermined number of tables including a glyph table, the system comprising:
- multiple first level font compressors for generating compressed TrueType font (CTF) data by separately processing each of the tables using a different compression scheme for each table;
- a first memory area for storing the CTF data representing the glyph table into a multitude of CTF data groups;
- a second memory area for storing the CTF data other than glyph table represented data into one of the CTF data groups;
- multiple second level font compressors for producing compressed data sets by separately processing each CTF data group;
- and
- a multiplexor for combining the compressed data sets to provide a final compressed TrueType font data set.
A system for decompressing a compressed representation of a TrueType font file comprising three merged compressed data sets with the first data set containing an updated table directory and twice compressed tables cvt, hdmx and VDMX and with the second and third data sets containing twice compressed glyph data and glyph code, respectively, said system comprising:
- means for splitting the merged three data sets into individual compressed first, second and third data sets;
- means for decompressing said individual compressed first, second and third data sets to produce intermediate compressed first, second and third data sets;
- means for further decompressing said intermediate compressed first data set to produce a TrueType table directory, tables cvt, hdmx and VDMX and glyph outlines;
- means for further decompressing said intermediate compressed second and third data sets to produce a glyph table;
- and
- means for rebuilding a TrueType loca table with said table directory and tables representing the TrueType font file.
A method for decompressing a compressed representation of a TrueType font file comprising three merged compressed data sets with the first data set containing an updated table directory and twice compressed tables cvt, hdmx and VDMX and with the second and third data sets containing twice compressed glyph data and glyph code, respectively, said method comprising:
- splitting the merged three data sets into individual compressed first, second and third data sets;
- decompressing said individual compressed first, second and third data sets to produce intermediate compressed first, second and third data sets;
- further decompressing said intermediate compressed first data set to produce a TrueType table directory, tables cvt, hdmx and VDMX and glyph outlines;
- further decompressing said intermediate compressed second and third data sets to produce a glyph table;
- and
- rebuilding a TrueType loca table with said table directory and tables representing the TrueType font file.
Dependencies are inferred from the claim text.