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