CF2.1 to CF2.2: Bug or bug fix?

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CF2.1 to CF2.2: Bug or bug fix?

Post by kipling »

A fellow CFer noted that my design "minerals" no longer renders as it used to. This seems to be a result of the CF2.1 to CF2.2 transition. I just dug out an old copy of CF2.1 and confirmed that there is a difference.

I have tried to diagnose, but not as far as diving into the source code. My guess is it is either the way alpha values are handled (the change log did mention an alpha bug fix - I may have been exploiting this bug) or in the way gamma values are handled. ... or maybe it is a change in agg.

I had noticed that CF2.2 now seems to be including gamma values in the PNG file, in that different image viewers, web browsers, and probably the PNG-to-JPEG filter on the CF server all display/convert dark colours consistently now, which wasn't the case for CF2.1, something that I had previously attributed to gamma values. I haven't delved into the CF2.2 code to discover whether there is different handling of gamma in the internal values stored in the images - this would obviously affect how the elements of an image are composited.

If it is a bug fix, then I will do my best to adjust my .cfdg's. If it is a bug, I can provide some stripped-down examples of code that illustrate the difference.

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