1 <?xml version="1.0" encoding="ISO-8859-1"?> 2 <!DOCTYPE quantization-tables [ 3 <!ELEMENT quantization-tables (table)+> 4 <!ELEMENT table (description , levels)> 5 <!ELEMENT description (CDATA)> 6 <!ELEMENT levels (CDATA)> 7 <!ATTLIST table slot ID #REQUIRED> 8 <!ATTLIST levels width CDATA #REQUIRED> 9 <!ATTLIST levels height CDATA #REQUIRED> 10 <!ATTLIST levels divisor CDATA #REQUIRED> 11 ]> 12 <!-- 13 JPEG quantization table created by Dr. Nicolas Robidoux, Senior Research 14 Scientist at Phase One (www.phaseone.com) for use with 2x2 Chroma 15 subsampling and (IJG-style, hence ImageMagick-style) quality level 16 around 75. 17 18 It is based on the one recommended in 19 20 Relevance of human vision to JPEG-DCT compression by Stanley A. Klein, 21 Amnon D. Silverstein and Thom Carney. In Human Vision, Visual 22 Processing and Digital Display III, 1992. 23 24 for 1 minute per pixel viewing. 25 26 Specifying only one table in this xml file has two effects when used with 27 the ImageMagick option 28 29 -define jpeg:q-table=PATH/TO/THIS/FILE 30 31 1) This quantization table is automatically used for all three channels; 32 33 2) Only one copy is embedded in the JPG file, which saves a few bits 34 (only worthwhile for very small thumbnails). 35 --> 36 <quantization-tables> 37 <table slot="0" alias="luma"> 38 <description>Luma Quantization Table</description> 39 <levels width="8" height="8" divisor="1"> 40 16, 16, 16, 18, 25, 37, 56, 85, 41 16, 17, 20, 27, 34, 40, 53, 75, 42 16, 20, 24, 31, 43, 62, 91, 135, 43 18, 27, 31, 40, 53, 74, 106, 156, 44 25, 34, 43, 53, 69, 94, 131, 189, 45 37, 40, 62, 74, 94, 124, 169, 238, 46 56, 53, 91, 106, 131, 169, 226, 311, 47 85, 75, 135, 156, 189, 238, 311, 418 48 </levels> 49 </table> 50 <!-- 51 If you want to use a different quantization table for Chroma (say), just add 52 53 <table slot="1" alias="chroma"> 54 <description>Chroma Quantization Table</description> 55 INSERT 64 POSITIVE INTEGERS HERE, COMMA-SEPARATED 56 </levels> 57 </table> 58 59 here (but outside of these comments). 60 --> 61 </quantization-tables> 62 63
