Question (mostly to Keymaster) about relations between level and RGB

[astudio]

As I uderstand for workflow with gamma 2.2

 RGB 255.255.255 level 1.0 = RGB 255.255.255 level 1.0
 RGB 128.128.128 level 1.0 = RGB 255.255.255 level 0.5
 RGB  64.64.64      level 1.0 = RGB 255.255.255 level 0.25
 
Is it true? Here my logic stopped.

If so, then for gamma 1.0 it's must to work in other way. How?
Do I need all material maps to use with gamma 2.2 ?
If I need to mix color with bitmap for reflection 1:1 what will be correct for corona's algorythm? To use amount 0.5 for map and color let's say RGB 64.64.64 level=1.0?
Is it same for using map with amount 0.25 and pure white with level=0.25?

My brain explodes. What way will be correct for any gamma workflow?

And another question:
As I understand, if I need some specific color, I can't just type it's RGB in diffuse color slot, because my gamma 2.2 will change it. Do CoronaSolidTex will work correct in this case?

And another one. What usercase is for CoronaConstantMtl?

Thank's to everybody, who can answer. :)

[Ondra]

As I uderstand for workflow with gamma 2.2

 RGB 255.255.255 level 1.0 = RGB 255.255.255 level 1.0
 RGB 128.128.128 level 1.0 = RGB 255.255.255 level 0.5
 RGB  64.64.64      level 1.0 = RGB 255.255.255 level 0.25
 
Is it true? Here my logic stopped.

Level is just a number the result from color picker gets multiplier with. So your equations will hold with any gamma.

If I need to mix color with bitmap for reflection 1:1 what will be correct for corona's algorythm? To use amount 0.5 for map and color let's say RGB 64.64.64 level=1.0?
Is it same for using map with amount 0.25 and pure white with level=0.25?

If you need to mix something, you can use CoronaMixTex, or just set the two values (color and texture), and set texture amount to 0.5. Level is applied AFTER the mix. Or it is applied before, but to both the color and the texture, these two formulations are equal.

As for the gamma workflow, corona will always do calculations in the linear space, so you can just use "what looks good" method ;). Of course, what will look good are input textures with removed gamma, which does 3dsmax for you automatically if you set gamma correctly in preferences.

And another question:
As I understand, if I need some specific color, I can't just type it's RGB in diffuse color slot, because my gamma 2.2 will change it. Do CoronaSolidTex will work correct in this case?

AFAIK the gamma correction is NOT applied to the numbers you type in, it only affects how the color is displayed. So typing 127 in will always give you 50% white.

[astudio]

Thank you for fast reply.
So if I need to get same color as in photoshop, what RGB I need to type? Today I just save color rectangle and put it in diffuse slot. But I know, this is stupid way. I use 2.2 gamma in all preferences slots.

[Ondra]

putting some RGB values into constant mtl should get you exactly the same values on output. Same thing with diffuse color under neutral lighting

[Juraj]

Today I just save color rectangle and put it in diffuse slot. But I know, this is stupid way.

Not stupid at all. I do this for every material that has no diffuse texture assigned, this way I can choose from pre-made color palletes and complimentary tones.
This is what I often have there and can quickly switch between colors and associated tones. Quick, handy. I lol at color selectors, which just work differently on almost every occasion
and I can't be bothered to do some translations hocus-bogus to figure which one it is.

Quick example:

[astudio]

Good to be in good company, Juraj.  ;)

But here I'm looking for workflow like in Dan Margulis "Photosop for professionals" book, where you may do color correction, even if you daltonian.

There is must be some rools, how to put RGB in diffuse and get exectly same color. It must be simple, but I can't get it.
And because of deadlines haven't time to be an artist and make tests.
First test must be a final render for commercial projects as for me.

[Ondra]

side note: if you use anything else than the color picker or CoronaSolidTex for constant colors, you are incurring quite high overhead to you renders.


One thing I could do is to add "pick color from bitmap" functionality to the SolidTex

[astudio]

Thank you. I learned new trick about picker from your side note. :) Pick from bitmap button will be great- don't need to open bitmap in mat editor.

Usually I get the name of color from my client from his printed catalog.
I go to on-line catalog and look for this name.
Get RGB > prepare color rectangle in photoshop >  save as bitmap > use in 3dmax as texture.
I'd like not to use PS in between.

Conclusions:

Good news: I may open bitmap with my colored square in material editor and pick color from it. This way I don't need to store it in material library. Never think about it.

Bad news: I can't put RGB value in no way.

Question1: In my example I need RGB 154 188 104. From mat editor when I pick I get RGB 84 130 35. Strangest thing for me, that even Hue value was changed from 63 to 60 in HSV. Is there some formula which give me right RGB values for my 2.2 gamma workflow?

Question 2: Right diffuse color in CoronaMtl gives me same result as in CoronaSolidTex. Why do you recommend  CoronaSolidTex?