Win8.1x64, 3x gtx580
Short description of error
For the long time I was wondering why is it impossible to render alpha-translucent colors in blender. It seemed like an obvious case of incorrect choice of premultiplication on my part, however regardless of what nodes or math I applied to output channels, the best I could do was faking it to look less prominent for each particular case.
So now I tried just outputting pure rgba(1, .5, .25, .25). Which in render view and upon saving gets outputted as a pure grey (or white with <1 alpha). This happens after all the node transformations have been done as in the nodes the color is recoverable, however once if it gets to "composite" view and/or saving, some color transformation gets applied affecting colors by intermediate alpha values. I get that color space transformations are unavoidable, however no possible transformation leading to particular result can be right.
Switching "View" color space from default/raw to others produces seemingly correct result for respective color spaces, but default/raw output, desaturates colors of low-intermediate alpha for some reason.
Not sure if somehow relevant - the Alpha Over compositing node produces alike result before even composite if the render image is being composited over a zero-alpha-white, while keeping everything intact over zero-alpha-black. That is - final output in semi transparent areas acts as if the image was composited over zero-alpha-white or gray before viewing/saving.
Exact steps for others to reproduce the error
- Render -> output is grey