Support for textures with negative values
Open, LowPublic


Support for textures with negative values

This very small patch adds support for textures containing negative values (i.e. OpenEXR)

The problem with Blender was that during Contrast & Brightness adjustment values below zero were being clamped. The main advantage of this 'feature' is to have more flexibility when dealing with the deform modifier.

A check box to enable this new behavior was added below Brighness, Contrast & Saturation sliders. Default value is disabled, which is the old behavior. Enabling it will gray out saturation, since it doesn't make sense, and mathematically speaking because RGB->HSV->RGB conversion doesn't expect negative values.

Using SVN 48705 (Blender 2.63)

A Blend file with an OpenEXR image containing negative values is included for testing; also contains two screenshots to see show the difference between the patched version and a non-patched one.


Sergey Sharybin (sergey) lowered the priority of this task from "Normal" to "Low".Apr 3 2015, 1:17 PM

This is quite niche application and also only affects old texture system. If we accept such functionality changes we need to be sure Cycles also works nicely with it.

Will try to find time to look into it, or maybe @Tamito Kajiyama (kjym3) is also interested in this?