Color/Tint -- What is it in pixel math terms?

Is it 'multiply'? Looks like it.

Definitely not 'overlay' or 'soft light' because there's no screening / lightening going on in the pixels above the midpoint threshold, and the other blending modes are arcane enough that they wouldn't seem likely.

Must be multiply, no?

Thanks.

I think it is purely subtractive and possibly linear at that. That is, tint is more like puting paint on something than anything else.

Here's a test: make a prim, set it to blank texture with "full bright" on (even blank is attenuated by noon-day sun unless full bright) and set the tint to something low luminosity. Take a screen grab and throw it into pshop and I think you find the RGB of the blank to be exactly that of the "tint".

From my own experience, yes, it seems essentially the same as setting the color layer to 'Multiply' in Photoshop, if the layer you are multiplying is a solid fill color. But you can only do solid colors on that layer, not a second image.

I agree and still think it's most likely 'multiply' -- and partly based on Introvert's formula, lol.

A full-bright prim sounds like it's the same as self-illumination in 3DS Max or Luminance in Cinema 4D (I use the latter). It's all white, no diffuse, so what you have essentially is 255,255,255, or in compositing math, 1,1,1.

So if you add a layer to that and set to multiply, you're multiplying by 1, no effect. Exactly as Introvert predicts.

Also, the 'tint' darkens highlights on pants and such. Multiply will always darken, which is why it's used for painting shadows on film mattes.

I haven't tested it in any detail, but it looks like just plain ole standard OpenGL texture modulation to me. (GL_MODULATE) That's texel * material color.

Not sure exactly how PS's multiply works. There's multiply AND Darken. Maybe one clips to 0-1, and the other doesn't? Or doesn't combine linearly?