Sorry, I think this one was clogged in the moderation queue and just now got dislodged. I believe this is from the subsequent discussion and patches which have now already been merged.
> On Jul 4, 2017, at 12:39 PM, Stefan Werner <[email protected]> wrote: > > Hi, > > I ran across one texture that I can’t quite figure out how to deal with it > correctly using TextureSystem. The original texture is a gray scale PNG with > alpha channel, and I’m converting it with maketx. I’m trying to get that back > as RGBA via the gray_to_rgb=1 option in the texture cache, but I always get > the gray channel as R and the alpha channel as G, with B and A empty/default. > > I stepped through the code, and I see that in > TextureSystemImpl::fill_gray_channels(), line 848, the case for two channel > input files only does the conversion when spec.alpha_channel = 1. When I use > TIFF for my cache file format, spec.alpha_channel is -1, when I use OpenEXR > as cache file format, spec.alpha_channel is 0. Maketx apparently only marks > TIFF as containing an alpha channel when there are 4 or more channels, see > tiffoutput.cpp line 485. OpenEXR does set the channel name to alpha. > > Is there a reason that fill_gray_channels() checks for index of the alpha > channel rather than just its presence? Is there any way that I can get this > texture to be read as RGBA through the texture cache? > > Thanks, > Stefan > _______________________________________________ > Oiio-dev mailing list > [email protected] > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org -- Larry Gritz [email protected]
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