Colour accuracy in Octane

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roeland
OctaneRender Team
Posts: 1822
Joined: Wed Mar 09, 2011 10:09 pm

We 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.
colors1.png
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.
colors2.png
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
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bepeg4d
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Location: Italy
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this is a great news, i've got a lot of problems with red emitters so this is really appreciated :D
can't wait for the new realize ;)
thanks roeland and all the otoy team
ciao beppe
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gabrielefx
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Posts: 1701
Joined: Wed Sep 28, 2011 2:00 pm

thank you,

checked, linear now works ok but please put an option called "legacy lut" (or whatever) to preserve the previous gamut because all my scenes now are useless.

all colors are gone...

Regards
quad Titan Kepler 6GB + quad Titan X Pascal 12GB + quad GTX1080 8GB + dual GTX1080Ti 11GB
kavorka
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Joined: Sat Feb 04, 2012 6:40 am

Excellent, can't wait for the update :)
Intel quad core i5 @ 4.0 ghz | 8 gigs of Ram | Geforce GTX 470 - 1.25 gigs of Ram
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pixelrush
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Location: Nelson, New Zealand

Perhaps gabrielefx can keep an older version of Octane on his PC as well if he thinks he might need to rerender older scenes. I'd rather move up/on to better and clean code than have legacy support for what amounts to a bug myself... :roll:
i7-3820 @4.3Ghz | 24gb | Win7pro-64
GTS 250 display + 2 x GTX 780 cuda| driver 331.65
Octane v1.55
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gabrielefx
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pixelrush wrote:Perhaps gabrielefx can keep an older version of Octane on his PC as well if he thinks he might need to rerender older scenes. I'd rather move up/on to better and clean code than have legacy support for what amounts to a bug myself... :roll:

in fact I'm using 3 different Octane for Max versions. 2.58f, 3.0c, 3.01 just now.

I think that one year of work can't be put in the trash.

In Vray there is an option called "legacy sun" and several questions appear when the plugin starts.

I'm not using Octane for Max to do experiments.
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ROUBAL
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Good news, because, currently the colors don't match colors in Photoshop. This leaded me to use small images samples (2x2 pixels) for some materials colors instead of built in procedural colors in some cases, using for that more textures than wished.
French Blender user - CPU : intel Quad QX9650 at 3GHz - 8GB of RAM - Windows 7 Pro 64 bits. Display GPU : GeForce GTX 480 (2 Samsung 2443BW-1920x1600 monitors). External GPUs : two EVGA GTX 580 3GB in a Cubix GPU-Xpander Pro 2. NVidia Driver : 368.22.
kavorka
Licensed Customer
Posts: 1351
Joined: Sat Feb 04, 2012 6:40 am

gabrielefx wrote:
pixelrush wrote:Perhaps gabrielefx can keep an older version of Octane on his PC as well if he thinks he might need to rerender older scenes. I'd rather move up/on to better and clean code than have legacy support for what amounts to a bug myself... :roll:

in fact I'm using 3 different Octane for Max versions. 2.58f, 3.0c, 3.01 just now.

I think that one year of work can't be put in the trash.

In Vray there is an option called "legacy sun" and several questions appear when the plugin starts.

I'm not using Octane for Max to do experiments.

I agree that a legacy feature should be implemented. You never know when a client will want to revisit a project down the line and you may want to introduce a new feature that has been implemented while keeping your colors the same.
Intel quad core i5 @ 4.0 ghz | 8 gigs of Ram | Geforce GTX 470 - 1.25 gigs of Ram
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