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Old 17 April 2015, 13:20   #2
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Join Date: Jun 2010
Location: NL/PL
Posts: 1,430
Originally Posted by jsr View Post
All of the generated pictures uses 24-bit palettes, but the converter can forced to convert them to 12-bit ones. The non-AGA Amigas are able to show the 24-bit palettes, but they only use the top 4-bit, which are not colour-correct shrinking, since for example $e1 will be $e, but in reality it should be $d ($e1 is much closer to $dd than $ee).
So, with the "f4b" switch the converter will colour-correctly shrink all the colours, then extend them again (also colour-correctly). By this the non-AGA machines will show the colours without brightness shifting.
However, since the quantizer works on 24 bit and the shrinking happens after the palette quantization, it can produce collosions, which can be more worse, than a non-correctly bright picture. (E.g. both the colours "3f89b1" and "4590a9" will be "4488aa" and the final image will use less colours.) So, use with care.
2 steps quantization - 24 bit to 12 bit (and error distribution) then 12 bit to CLUT size.
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