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BC1 and BC3 RGB result is different

Open SimpsonGSD opened this issue 5 years ago • 9 comments

Hi, as far as I'm aware BC1 and BC3 should produce the same result for RGB data for the same input texture. However, with high frequency data in the blue channel BC1 produces RG data with blue data in but in BC3 the RG data is almost unaffected by the blue channel. Why is this? Which one is correct? For my needs BC3 produces a much better RGB result, I just don't need any alpha as it's black.

SimpsonGSD avatar Apr 28 '20 11:04 SimpsonGSD

@SimpsonGSD Are you using the application GUI, CLI, or the Libraries CMP_Core, Compressonator?

NPCompress avatar May 07 '20 14:05 NPCompress

I was testing with the GUI.

SimpsonGSD avatar May 07 '20 14:05 SimpsonGSD

@SimpsonGSD In the GUI Set Application options dialog are you using "Encode with" CPU or HPC?

image

NPCompress avatar May 07 '20 15:05 NPCompress

@NPCompress CPU

SimpsonGSD avatar May 07 '20 15:05 SimpsonGSD

I've just tested this with 4.0 GUI and BC1 and BC3 now produce the same result. The result is now worse than the BC3 output from 3.2 but at least they are consistent. I've attached my unit test texture. BC1_UnitTest

SimpsonGSD avatar May 15 '20 13:05 SimpsonGSD

@SimpsonGSD What is the quality setting? Have you tried HPC with q=1.0?

NPCompress avatar May 15 '20 13:05 NPCompress

@NPCompress Yeah I have HPC encode enabled and quality 1.0.

SimpsonGSD avatar May 15 '20 13:05 SimpsonGSD

@SimpsonGSD HPC PSNR is expected to be about -0.2dB from CPU, The CPU decoder codec had a update that may also make a diff in PSNR calc.

NPCompress avatar May 15 '20 13:05 NPCompress

@SimpsonGSD I will look at the sample to see if quality can be improved for the next update

NPCompress avatar May 15 '20 13:05 NPCompress

The issue has been resolved in current release v4.4

NPCompress avatar Jul 19 '23 19:07 NPCompress