Am 28.04.2010 19:00, schrieb Thorsten Froehlich:
> On 27.04.10 23:05, clipka wrote:
>> BTW, as a matter of fact, the wrong channel ordering is a 3.7 issue;
>> POV-Ray 3.6 at least did it the right way round.
>>
>> I consider the use of RGB instead of YCbCr a bug (already filed as
>> FS#103 ;-)).
>
> No, it isn't a bug. This *really* is intentional behavior! With the
> correct settings in other places (not sure if they are), you can get rid
> of a lot of color bleeding when using sharply ray-traced objects by
> using RGB.

 From experiments, I really don't see any advantage of RGB over YCbCr 
without chroma sub-sampling.

To the contrary: At the same output file size, YCbCr without chroma 
sub-sampling appears to give slightly superior quality.

So given that the same (or even better) quality/size tradeoff as RGB 
seems to be obtainable in a fully JFIF-compatible way, that's the way to 
go if I'm asked.

Even if for some reason we would want to do non-JFIF-compatible JPEG 
output, I strongly advocate doing so only when the user /explicitly/ 
chooses it via some option. The image file format commonly known as 
"JPEG" /is/ actually JFIF, so by default POV-Ray should follow that 
convention for the sake of compatibility.

Note that if quality is paramount, JPEG is a bad choice of output file 
format anyway, so I don't see much of a point in sacrificing 
compatibility for quality with this format.

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