imagemagick/www/source/quantization-table.xml

69 lines
2.3 KiB
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>