hello,
as i’ ve understood, you have a model with its color map, & you want to import them into zBrush.
Well when you have imported your model (obj maybe), sometimes it has texture info with it so it appears with its map, color etc.
If no (I think it usually the case) then you have to import your color texture (diffuse?) throught texture menu,
or, within the tool menu/texture map and then clic on the rectangle preview (but I suggest to not use this way, because sometimes the map won’ t be in the right orientation, this is why I suggest to use the ‘texture’ menu at the top, and clic ‘import’.
You have the possibility to inverse the texture, usually in y axis usnig the arrow icone, in this same ‘texture’ menu.
And then you go to the tool menu/texture map to ‘import’ it, or apply it using the rectangle uv texture previsualisation.
Don’ t forget to activate it in case where it is not, by clicking on the ‘texture on’ button.
You are now able to see the texture map onto the model. Now, if you want to edit it with usual brush etc, you just have to ‘project’ this texture map onto your model, by going to same tool menu/polypaint/polypaint from texture.
Just remember the ‘quality’ of the polypaint is related to the number of polygones of the model, so be sur to check it, and to subdivide if needed.
When you have finished to edited /modify your polypaint, then you wan to transfer your ‘new’ polypaint on the map, so you will have to go back to tool menu/texture map/new from polypaint
ps: your model has to be already unwrapped of course.
Note: if you are a user of layers, and you want to use ‘new from polypaint’, then be sure to not be in ‘record mod’, otherwise you will get a black/‘crunch’ map.
I hope I was clear & it will help you a bit.