On 11/10/2009 8:02 AM, Ive wrote:
> SharkD wrote:
>> I'm converting a bunch of CIE xyY coordinates to SRGB. Obviously, most
>> (if not all) colors lies outside the SRGB gamut. However, what's the
>> best way to "fake" it?
>>
>> Should I normalize each color based on the minimum and maximum of all
>> the colors? Should I simply clip values below 0 and above 1?
>>
>> Mike
>
>
> Your color conversion from xyY to sRGB as used within your file in
> p.b.sf is plain wrong for 3 reasons:
>
> 1.) The luminance values given in the table are obviously within a range
> of 0 to 100 (thats commonly used) but your xyY -> xyz conversion assumes
> luminance within the 0.0 to 1.0 range.
Thanks! That made a big difference.
> 2.) For the xyY to sRGB color conversion you *NEED* also chromatic
> adaption (Bradford adaption is commonly used) because xyY uses reference
> white D50 while sRGB uses the D65 whitepoint.
I think this has already been taken care of since the results of the
function are so similar to the Lindbloom color converter whith SRGB
output set to D65.
> 3.) No gamma correction for the rgb values! Just set assumed_gamma to
> 1.0 for POV version prior 3.7.
I'm not so concerned with whether the colors in the output image are a
100% match since I'm also applying lighting and radiosity and so on.
Mike
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