Alpha channel should be 1 by default, rather than 0 #2197
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Signed-off-by: pylee <[email protected]>
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Thanks for the contribution @pennelee ! Added the devdays25 label. |
cozdas
requested changes
Sep 26, 2025
| inBitDepthBuffer[4*pixelsCopied+1] = *gPtr; | ||
| inBitDepthBuffer[4*pixelsCopied+2] = *bPtr; | ||
| inBitDepthBuffer[4*pixelsCopied+3] = aPtr ? *aPtr : (Type)0.0f; | ||
| inBitDepthBuffer[4*pixelsCopied+3] = aPtr ? *aPtr : (Type)1.0f; |
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Thanks for your contribution.
The idea is if the input image doesn't have an alpha channel, we need to consider the pixels as fully opaque instead of fully transparent (alpha=0). For floating point types fully opaque is represented as 1.0f but for integer types it needs to be the max value the type can hold (e.g. for 8-bit types it's 255)
Please check BithDepthUtils.h, the templated struct BitDepthInfo will be useful.
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Ahh, I got you, thanks @cozdas! Let me take a look at that file and fix it, will comment if any questions.
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Related to issue #1781.
For CPU processor, when source has no alpha (RGB) but dest does (RGBA) make it default to 1.
GPU Processors (new and legacy) did not seem to have this issue, alpha was already set to 1. Let me know if this is not the case.
Tested changes with ocioconvert and changed the output to force RGBA, since the default is to use inplace conversion (did not check in those changes).
Tested with all the ocioconvert test cases (basic, --lut, --view, --invertview --namedtransform, --invnamed transform), and various EXR file sizes.
Before the changes alpha would be 0, so image was not viewable. After the changes then images can be viewed and from inspection the alpha channel is now 1.0.
Also updated related CPU tests to reflect non zero alpha values.