Im trying to turn this leg black but I dont want to lose the value tones on it. When you choose luminosity its literally pointless I could have just painted that black if it wasnt going to actually do color replacement. Could someone please help I want this leg black but still with the same shadowing and highights
This is literally what happens when you select luminosity I might as well use the baint brush tool and put the hardness on Zero because thats literally what this is you can see that the shadowing and highlight detail it originaly had is now gone i dont want that! I want to just be able to use color replacement of black without it having the value tones in grey or with the luminosity where its literally just solid black
It is in no way clear what tools you are actually using with what settings, so this is not realyl telling us anything. That aside, why would you even fiddle with luminosity? All it takes is to remove the color using a saturation adjustment and then perhaps a levels or curves one after that to tweak the contrast. Most blacks in the real world are just dark greys, anyway, and textile weaves have a specific behavior to begin with due to thei anisotropic texture.
I'm afraid you misunderstand this on a fundamental level. Black isn't a "color", it's the complete absence of any color or luminosity at all. It's the absolute zero point.
In other words, this is working entirely as it should, and there's no way it's possible to retain any values at all - as long as you pick absolute black as the brush color. What you want is to desaturate, and then lower the brightness just enough so that it looks black.
Look around you. Find a black object and look closer: it's not black at all; it's various shades of dark gray.
This has nothing to do with Photoshop. This is the optical properties and behavior of color and light. This is how it works out in the physical world.