Combine material's main texture and main color

I am in the process of combining textures into a single map to lower draw calls, but I am realizing that I have set the main color for all my textures that I want to combine differently. How do I combine a material’s main texture and main color into a single draw call? Is there a way to do it with an external program like photoshop? Thanks a lot.

If you are using the builtin shaders, you can mimic the effect of the main color in photoshop easily. The result color of the texture is Texture2MainColor.
So if you multiply the texture with the maincolor in photoshop, and then add a copy off the result with that, you get the actual color. You would then have to set the material main color to 128 128 128 gray.