Sky posterization

[Nick Fedoseev]

Ver 0.13.x: the sky is rendered with high level of posterization in some cases. Not seen in 0.12.x

[gzotti (georg-zotti)]

this seems to depend on hardware and/or drivers, I have seen nice&smooth and such posterization effects. One source is also the zodiacal light texture, which almost necessarily causes some striping. How to solve, 16bit textures?

[Alexander Wolf (alexwolf)]

Nick, can you disable zodiacal light (Ctrl+Shift+Z) and check it again?

[Nick Fedoseev (nick-ut2uz)]

Disabling zodiacal light changes the borders of posterization, but it still exists.

I'm playing with different settings, drivers and devices in order to catch the source of posterization. It looks like the result of rescaling the range of 8 bit sRGB gradient instead of generation a new one.

May be useful: adding some noise does excellent result for hiding posterization edges.

[Nick Fedoseev (nick-ut2uz)]

Attached image illustrates the idea of noise addition. Both upper and lower gradient lines use the same palette of 64 B/W colors.

[gzotti (georg-zotti)]

Great to have a new contributor!

Ruslan is working on this under https://github.com/Stellarium/stellarium/issues/131