Colour accuracy in Octane
Posted: Wed Sep 19, 2012 7:06 amWe have done work on improving color accuracy in Octane. These changes are included in the OctaneRender for
3ds max beta 3.01, and will be in the next release of Octane Standalone. As a consequence there will be a
difference in colors when rendering in beta 3.01 or earlier, and later versions.
In the following image you can compare a color wheel texture with a rendering of this texture on a quad. The
renderings are tonemapped without film curve and with a gamma value of 2.2, and the texture was loaded with
the same gamma value.
On the left the previous release, on the right is the improved version.
Note the improvement in saturation, and the accuracy of blue hues.
Another test image: a simulation of some LED colors: indigo (430nm), blue (470nm), green (525nm), amber (585nm)
and red (660nm), using Gaussian spectra. The new version is at the bottom.
The indigo looks like the deeply saturated blue as it should, and the other colors, especially the red, are properly
saturated.
These changes should resolve most issues with rendering brightly colored objects, like a wall painted in deep red.
There has also been a change to how colors are clipped if they fall outside the RGB gamut (Octane uses the sRGB
primaries), or are too bright. Colors outside the gamut are desaturated while keeping the hue and brightness
constant. This however limits the effect of increasing saturation in the imager settings. Overly bright colors are
gradually desaturated to white.
The 3ds max users can already test these changes, and an update of the standalone version will be released
soon.
--
Roeland
3ds max beta 3.01, and will be in the next release of Octane Standalone. As a consequence there will be a
difference in colors when rendering in beta 3.01 or earlier, and later versions.
In the following image you can compare a color wheel texture with a rendering of this texture on a quad. The
renderings are tonemapped without film curve and with a gamma value of 2.2, and the texture was loaded with
the same gamma value.
On the left the previous release, on the right is the improved version.
Note the improvement in saturation, and the accuracy of blue hues.
Another test image: a simulation of some LED colors: indigo (430nm), blue (470nm), green (525nm), amber (585nm)
and red (660nm), using Gaussian spectra. The new version is at the bottom.
The indigo looks like the deeply saturated blue as it should, and the other colors, especially the red, are properly
saturated.
These changes should resolve most issues with rendering brightly colored objects, like a wall painted in deep red.
There has also been a change to how colors are clipped if they fall outside the RGB gamut (Octane uses the sRGB
primaries), or are too bright. Colors outside the gamut are desaturated while keeping the hue and brightness
constant. This however limits the effect of increasing saturation in the imager settings. Overly bright colors are
gradually desaturated to white.
The 3ds max users can already test these changes, and an update of the standalone version will be released
soon.
--
Roeland
