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Old 05 November 2016, 14:24   #92
pandy71
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Join Date: Jun 2010
Location: PL
Posts: 1,532
Color Clock is 3.58MHz and you can feed maximum 7.16MB over RGA/D bus - this is internal chipset design limitation (all except AGA where tricks similar to DDR are used to increase overall bandwidth) - some cycles may be available for CPU.
Above valid for NTSC, PAL is marginally slower ((4.43*4)/5).
And once again - problem is not in transfer speed (number of CLUT updates is identical on ST and Amiga as both systems suffer from same memory bandwidth limitations) but in quality of algorithms for color quantization and error distribution - on 2 bitplanes ST/STe is able to beat Amiga with 4 bitplanes and PCHG (as Dynamic Hires use CPU so it is more close to ST).
It is easy to verify - best Amiga graphic converter capable to do dynamic CLUT updates - HAMLab - is incapable to deliver same quality (perceived by observer) as http://www.leonik.net/dml/sec_pcs.py tool - we talking about lack of visible horizontal stripes (obvious problem with overloading CLUT changes - suboptimal color selection).
This is clearly visible on mentioned already 'elevation by The Electronic Knights' - those pictures are special class pictures very well suited to use Dynamic CLUT techniques (quite well balanced, plenty of luminance details but overall chrominance is very averaged - some contrasting chrominance is also well concentrated but at the same time not to diversified - all this lead to relatively small variance in color histogram, also color changes in vertical direction are almost penalty free).
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