Gamma Correction in maps for monochrome maps

[3dwannab]

I'm having trouble controling the gamma of say monochrome maps for bumps to apply gamma 1.0 to them. I tend to use a script to apply auto-gamma to all maps but wanted to control the gamma through the color correct modifier for the the bump slot for example. As using G1.0 for monochrome maps leads to better results, it would be nice to control this with an external map.

See results. Beauty pass is fine but the corrected gamma has no effect on the Normal shading pass.

[3dwannab]

Bump.

I'm starting to think this is a bug. Can someone on the team check it out. Shall I post on mantis?

Thanks.

[romullus]

You may want to check this with Vray or Mental Ray first. Color correct map has no effect on bump mapping at all, AFAIK.

[maru]

Color correct map has no effect on bump mapping at all, AFAIK.

I think so too. I will check it though.

[3dwannab]

Okay, thanks. I'd just like to control the gamma of the bump, displace maps through a CC map. And not through the loader.

[3dwannab]

Just tested there. VRay has the same result. I couldn't try Mental Ray as it doesn't have any element that displays bumped normals.

[maru]

I just checked this. You do not need to see the element, you can see the effect on beauty. It behaves the same way with MR - it is impossible to alter bump using CC or Output node. So it looks like a Max limitation, but maybe it is possible to hack it? :)

However, you can always (also in Corona) alter a normal map using CC or Output.

[3dwannab]

I tried using the Corona Normal modifier map and checked the box for adding gamma but this was not a great result. I'll try see if I can add a curve to the output map to replicate the 1.0 gamma. I post back later my result.

[romullus]

That's why Corona needs something similar like VrayColor2Bump map.

[3dwannab]

The Corona Bitmap Map could have a checkbox to do the same and have a gamma spinner in there too which would be great. Better solution to controlling gamma than the loader method.

I think someone on here suggested better color mapping but was shot down by Ondra. Found it:

I think he means something like color correction setting, for example you put 0,8 to boost contrast. Not sure but maybe it is the same as rgb offset in output tab?

this is simply not gonna happen ;)

There are already enough output settings, and if not, we can add more, but NOT gamma.

But this would be different as it'll act like the VrayColor2Bump in the sense it'll be two maps combined in one. Maybe Ondra might change his opinion on this. ;]

[3dwannab]

No amount of tweaking the curve in an output map has any effect on the bump slot. The displace however is different and reflects any tweaking in an output map and a CC map. This has to be a 3ds max bug.

Here's just a simple comparison between 2.2 and 1.0 gamma on their own. The same bump value is used (50) in each. As you can see it's a huge comparison. The map I'm using has 128 grey background and full black and white values on the text.

Diffuse is left at auto like normal in the example, just the bump gammas are changed to show the comparison.

Shall I post on mantis or request feature, what do you guys think?

[romullus]

Shall I post on mantis or request feature, what do you guys think?

Neither. That's not a bug, it's just 3ds max treats bump maps very differently from the rest maps. Map that would allow to work with bump maps much easier, is requested already: https://forum.corona-renderer.com/index.php/topic,1475.0.html

[pokoy]

Please try the same with the ColorCorrect Map from Cuneyt Ozdas (get the link from maxplugins.de), I seem to remember this worked fine there.

AFAIR the underlying problem is that color and bump are handled independently through different channels and maps that are designed to do color transforms will work only on the color channel and dismiss bump. Hence the bump amount paramter in the maps output controls, that's the only one affecting bump. It would be great if this would be finally changed but then again they should update and improve the whole output/CC section.

[Juraj]

it's just 3ds max treats bump maps very differently

Why does even 3dsMax come into equation ? It's Corona shader after all. Bit confused by this. I could understand it would be possible limitation of 3dsMax Bitmap loader, but bump mapping which is Renderer's property ?

[Ondra]

it's just 3ds max treats bump maps very differently

Why does even 3dsMax come into equation ? It's Corona shader after all. Bit confused by this. I could understand it would be possible limitation of 3dsMax Bitmap loader, but bump mapping which is Renderer's property ?

tl;dr: 3ds Max has no buit-in:
a) bump mapping support
b) gamma control support

and normal mapping shader is expected to load sub-maps with properties a) and b). This makes the implementation a bit... weird.