1、 Reference number ISO/IEC 14492:2001/Amd.3:2012(E) ISO/IEC 2012INTERNATIONAL STANDARD ISO/IEC 14492 First edition 2001-12-15 AMENDMENT 3 2012-12-01 Information technology Lossy/lossless coding of bi-level images AMENDMENT 3: Extension to colour coding Technologies de linformation Codage avec ou sans
2、 perte des images au trait AMENDEMENT 3: Extension au codage de la couleur ISO/IEC 14492:2001/Amd.3:2012(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which a
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7、org Published in Switzerland ii ISO/IEC 2012 All rights reservedISO/IEC 14492:2001/Amd.3:2012(E) ISO/IEC 2012 All rights reserved iiiForeword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide sta
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11、 Standard requires approval by at least 75 % of the national bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. Amendment
12、 3 to ISO/IEC 14492:2001 was prepared jointly by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information, in collaboration with ITU-T. The identical text is published as ITU-T Rec. T.88 (2000 E)/Amd.3. ISO/I
13、EC 14492:2001/Amd.3:2012 (E) Rec. ITU-T T.88 (2000)/Amd.3 (05/2011) 1 INTERNATIONAL STANDARD ITU-T RECOMMENDATION Information technology Lossy/lossless coding of bi-level images Amendment 3 Extension to colour coding 1) Clause 2, Normative References Append a new reference as follows (with the addit
14、ions underlined): Recommendation ITU-T T.45 (2000), Run-length colour encoding. 2) Clause 4.2, Symbol definitions Insert new symbols COLEXTFLAG, CPCOMPLEN, CPDEFCOLS, CPEXCOLS, CPNCOMP, CPNVALS, GBCOLS, GBCOMBOP, GBFGCOLID, SBCOLS, SBCOLSECTSIZE and SBFGCOLID as follows (with the additions underline
15、d): (Symbols left untouched) Clow Low-order 16 bits of C COLEXTFLAG A parameter indicating whether the generic region segment is extended to represent a coloured bitmap CONTEXT The values of the pixels in a template used in the generic or generic refinement decoding procedure CPCOMPLEN The length (i
16、n bytes) of each components value CPDEFCOLS The default colour set CPEXCOLS The colours defined in the colour palette segment CPNCOMP The number of colour components CPNVALS The number of colour values coded in this segment (Symbols left untouched) GB The prefix used for many of the variables associ
17、ated with a generic (bitmap) region decoding procedure GBCOLS An array containing the colours used in a generic region segment GBCOMBOP The combination operator used in a generic region decoding procedure GBFGCOLID The 4-byte integer indicating the foreground colour of the generic region segment (Sy
18、mbols left untouched) SB The prefix used for many of the variables associated with a symbol (bitmap) region decoding procedure SBCOLS An array of colours used in a text region segment SBCOLSECTSIZE The colour section length ISO/IEC 14492:2001/Amd.3:2012 (E) 2 Rec. ITU-T T.88 (2000)/Amd.3 (05/2011) (
19、Symbols left untouched) SBDEFPIXEL The default for pixels in a text region SBFGCOLID The three 1-byte integers indicating the foreground colour of the text region segment (Symbols left untouched) 3) Clause 6.2.2, Input parameters Add new rows of GBCOLS, GBCOMBOP and COLEXTFLAG after GBATY 4 , and ad
20、d a new Note f), in Table 2 as follows (with the additions underlined): Table 2 Parameters for the generic region decoding procedure Name Type Size (bits) Signed? Description and restrictions (Rows left untouched) GBATY 4Integer 8 Y The Y location of the adaptive template pixel A 4 . b)GBCOLS Array
21、of colours (colour palette) An array containing the colours used in this generic region. f)GBCOMBOP Operator The combination operator for this generic region. Shall take on the value REPLACE.f)COLEXTFLAG Integer 1 N A parameter indicating whether the generic region segment is extended to represent c
22、oloured bitmap. (Notes left untouched) f)Unused if COLEXTFLAG = 0. 4) Clause 6.2.4, Variables used in decoding Add a new row of GBFGCOLID after CONTEXT, and add a new Note b) in Table 4 as follows (with the additions underlined): Table 4 Variables used in the generic region decoding procedure Name T
23、ype Size (bits) Signed? Description and restrictions (Rows left untouched) CONTEXT Integer 16 N The values of the pixels in the template. a)GBFGCOLID Integer 32 N The 4-byte integer indicating the colour palette ID of the foreground colour for the generic region segment. b)(Notes left untouched) b)U
24、nused if COLEXTFLAG = 0. 5) New clause 6.2.7, Colour extension of generic region segment Add a new clause 6.2.7 after clause 6.2.6, as follows: 6.2.7 Colour extension of generic region segment If COLEXTFLAG is 1, after the decoding procedure described in 6.2.5 or 6.2.6, read GBFGCOLID which is a 4-b
25、yte integer indicating the colour palette ID, and set the colour specified by GBCOLSGBFGCOLID to the segments foreground colour. The background colour of the segment of which COLEXTFLAG is 1 is regarded as transparent. NOTE GBFGCOLID (the foreground colour information) has a fixed 4-byte field and i
26、s put at the end of the region segment only when COLEXTFLAG is 1. The decoder can find the address of GBFGCOLID by subtracting 4 from the segment data length recorded in the segment header. ISO/IEC 14492:2001/Amd.3:2012 (E) Rec. ITU-T T.88 (2000)/Amd.3 (05/2011) 3 6) Clause 6.4.2, Input parameters R
27、evise the description and restrictions of SBCOMBOP, add new rows of COLEXTFLAG and SBCOLS after SBRATY 2 , and new Notes e) and f) in Table 9 as follows (with the additions underlined): Table 9 Parameters for the text region decoding procedure Name Type Size (bits) Signed? Description and restrictio
28、ns (Rows left untouched) SBCOMBOP Operator The combination operator for this text region. May take on the values OR, AND, XOR, XNOR and REPLACE. e)(Rows left untouched) SBRATY 2Integer 8 Y The Y location of the adaptive template pixel RA 2 . c)COLEXTFLAG Integer 1 N A parameter indicating whether th
29、e generic region segment is extended to represent coloured bitmap. SBCOLS Array of colours An array containing the colours used in this text region. f)(Notes left untouched) e)REPLACE operator is used if and only if COLEXTFLAG = 1. f)Unused if COLEXTFLAG = 0. 7) Clause 6.4.4, Variables used in decod
30、ing Add new rows of SBCOLSECTSIZE and SBFGCOLID after HO I , and Note b) after Note a) in Table 11 as follows (with the additions underlined): Table 11 Variables used in the text region decoding procedure Name Type Size (bits) Signed? Description and restrictions (Rows left untouched) HO IInteger 32
31、 N The height of IBO I . a)SBCOLSECTSIZE Integer 32 N The colour section length. b)SBFGCOLID Array of integers An array of colour palette ID, indicating the colour of each symbol instance. b)a)Unused if SDREFINE = 0. b)Unused if COLEXTFLAG = 0. 8) Clause 6.4.5, Decoding the text region Insert Figure
32、 AMD3-1 after Figure 17 as follows: Initial STRIPT values First strip Second strip Last strip Colour section Figure AMD3-1 Coded structure of a text region extended for colour text ISO/IEC 14492:2001/Amd.3:2012 (E) 4 Rec. ITU-T T.88 (2000)/Amd.3 (05/2011) 9) Clause 6.4.5, Decoding the text region In
33、sert Figure AMD3-2 after Figure 20: Colour palette IDs Colour section length Figure AMD3-2 Coded structure of colour section 10) Clause 6.4.5, Decoding the text region Insert new Notes after Figure AMD3-2: NOTE 3bis If COLEXTFLAG is 1 then a colour section, which specifies the colours of all symbol
34、instances, is put at the end of the region as shown in Figure AMD3-1. The colour section consists of two parts as shown in Figure AMD3-2: colour palette IDs and colour section length. The colour palette IDs, which is encoded in the data structure based on Rec. ITU-T T.45, contains the information th
35、at specifies the colour of every symbol instances in the segment. The colour section length is a 4-byte field that contains the length of the colour section, in bytes. NOTE 3ter The background colour of the segment of which COLEXTFLAG is 1 is regarded as transparent. 11) Clause 6.4.5, Decoding the t
36、ext region Change the procedures itemized by 3) and 4) to 4) and 5) respectively, and insert a new procedure 3) as follows (with the modifications and additions underlined): 3) If COLEXTFLAG is 1, decode the colour section as described in 6.4.12. (Procedures left untouched) 4) Decode each strip as f
37、ollows: (Procedures left untouched) 5) After all the strips have been decoded, the current contents of SBREG are the results that shall be obtained by every decoder, whether it performs this exact sequence of steps or not. 12) Clause 6.4.5, Decoding the text region In the sub-procedure 4)-c), which
38、is previously itemized by 3)-c), change the sub-sub-procedures itemized by ix), x) and xi) to x), xi) and xii) respectively, and insert a new sub-sub-procedure ix) after procedure viii), as follows (with the modifications and additions underlined): ix) If COLEXTFLAG is 1, set the colour specified by
39、 SBCOLSSBFGCOLIDNINSTANCES to the foreground colour of the symbol instance bitmap IB I . x) Draw IB Iinto SBREG. Combine each pixel of IB Iwith the current value of the corresponding pixel in SBREG, using the combination operator specified by SBCOMBOP. Write the results of each combination into that
40、 pixel in SBREG. xi) Update CURS as follows: (Procedures left untouched) xii) Set: NINSTANCES = NINSTANCES + 1 13) Clause 6.4.5, Decoding the text region Insert a new Note at the end of 6.4.5, as follows: NOTE 6 The colour palette (SBCOLS) is created by concatenating the default colour set (CPDEFCOL
41、S) and the additional colours (CPEXCOLS) defined in the colour palette segment referred to by this segment. ISO/IEC 14492:2001/Amd.3:2012 (E) Rec. ITU-T T.88 (2000)/Amd.3 (05/2011) 5 14) New clause 6.4.12, Colour section Add a new clause 6.4.12 after clause 6.4.11.5, as follows: 6.4.12 Colour sectio
42、n If COLEXTFLAG is 1, the colour information recorded in the colour section needs to be decoded as shown in this clause. 6.4.12.1 Colour section length The decoding procedure of the colour section begins with achieving its top address by subtracting the SBCOLSECTSIZE from the segment data length def
43、ined in the segment header. SBCOLSECTSIZE is a 4-byte field at the end of the text region segment data part. The decoder can find the end of the data part by reading the segment data length in the segment header. 6.4.12.2 Colour palette IDs The field of the colour palette IDs is decoded in accordanc
44、e with Rec. ITU-T T.45 and the result is stored in SBFGCOLID. The number of elements in SBFGCOLID is equal to the number of symbol instances in the text region segment (SBNUMINSTANCES). NOTE If the codestream has the coloured text region segment, the ITU-T T.45 for colour palette IDs in the colour s
45、ection is restricted as follows: The number of colour components is 1 (NCOMP = 1 in the header of ITU-T T.45 codestream). The length of each colour components value is 1-byte (COMPLEN = 1 in the header of ITU-T T.45 codestream). The number of colour values is equal to SBNUMINSTANCES (NVALS = SBNUMIN
46、STANCES in the header of ITU-T T.45 codestream). 15) New clause 6.8, Colour palette decoding procedure Add a new clause 6.8 after clause 6.7.5, as follows: 6.8 Colour palette decoding procedure 6.8.1 General description This decoding procedure is used to decode a set of colours; these colours can th
47、en be used by generic and text region decoding procedures. 6.8.2 Input parameters The colour palette segment requires no input parameter. The parameters to this decoding procedure are shown in Table AMD3-1. Table AMD3-1 Parameters for the colour palette decoding procedure Name Type Size (bits) Signe
48、d? Description and restrictions CPNCOMP Integer 8 N The number of colour components. CPCOMPLEN Integer 8 N The length (in bytes) of each components value. Make take on the values 1, 2 or 4. CPNVALS Integer 8 N The number of colour values coded in this segment. ISO/IEC 14492:2001/Amd.3:2012 (E) 6 Rec
49、. ITU-T T.88 (2000)/Amd.3 (05/2011) 6.8.3 Return value The variable whose value is the result of this decoding procedure is shown in Table AMD3-2. Table AMD3-2 Return value from the colour palette decoding procedure Name Type Size (bits) Signed? Description and restrictions CPDEFCOLS Array of colours The default colour set. CPEXCOLS Array of colours The colours defined in this segment. 6.8.4 Decoding the colour palette The data part shall be stored as a sequence of the colour value (CVAL) that consists of CPNCOMP fields, and
