1 <?xml version="1.0" encoding="ISO-8859-1"?>
2 <!DOCTYPE quantization-tables [
3 <!ELEMENT quantization-tables (table)>
4 <!ATTLIST quantization-tables xmlns CDATA #FIXED "">
5 <!ELEMENT table (description , levels)>
6 <!ATTLIST table xmlns CDATA #FIXED "">
7 <!ATTLIST table alias NMTOKEN #REQUIRED>
8 <!ATTLIST table slot CDATA #REQUIRED>
9 <!ELEMENT description (#PCDATA)>
10 <!ATTLIST description xmlns CDATA #FIXED "">
11 <!ELEMENT levels (#PCDATA)>
12 <!ATTLIST levels xmlns CDATA #FIXED "">
13 <!ATTLIST levels divisor CDATA #REQUIRED>
14 <!ATTLIST levels height CDATA #REQUIRED>
15 <!ATTLIST levels width CDATA #REQUIRED>
18 JPEG quantization table created by Dr. Nicolas Robidoux, Senior Research
19 Scientist at Phase One (www.phaseone.com) for use with 2x2 Chroma
20 subsampling and (IJG-style, hence ImageMagick-style) quality level
23 It is based on the one recommended in
25 Relevance of human vision to JPEG-DCT compression by Stanley A. Klein,
26 Amnon D. Silverstein and Thom Carney. In Human Vision, Visual
27 Processing and Digital Display III, 1992.
29 for 1 minute per pixel viewing.
31 Specifying only one table in this xml file has two effects when used with
32 the ImageMagick option
34 -define jpeg:q-table=PATH/TO/THIS/FILE
36 1) This quantization table is automatically used for all three channels;
38 2) Only one copy is embedded in the JPG file, which saves a few bits
39 (only worthwhile for very small thumbnails).
42 <table slot="0" alias="luma">
43 <description>Luma Quantization Table</description>
44 <levels width="8" height="8" divisor="1">
45 16, 16, 16, 18, 25, 37, 56, 85,
46 16, 17, 20, 27, 34, 40, 53, 75,
47 16, 20, 24, 31, 43, 62, 91, 135,
48 18, 27, 31, 40, 53, 74, 106, 156,
49 25, 34, 43, 53, 69, 94, 131, 189,
50 37, 40, 62, 74, 94, 124, 169, 238,
51 56, 53, 91, 106, 131, 169, 226, 311,
52 85, 75, 135, 156, 189, 238, 311, 418
56 If you want to use a different quantization table for Chroma, for example,
59 <table slot="1" alias="chroma">
60 <description>Chroma Quantization Table</description>
61 INSERT 64 POSITIVE INTEGERS HERE, COMMA-SEPARATED
65 here (but outside of these comments).
67 </quantization-tables>