Can I import an image as paint layer?

I mean coloured image not texture

A plane

on which a photo is as Vertex Color and the color is on a Layer ?

Sorry, you lost me
I use digital sculpting SW on PC (MUDBOX), I can create image and then import a picture as a diffuse paint layer. I can also use SW like UVMAPPER to map the image to the object.
Can I do something similar Nomad?

Is there a video about it so that I can see what you mean? I only know and use Nomad Sculpt, but I know that very well. The whole thing is very limited with Nomad Sculpt, but there may be workarounds.

in PC SW you can create object like BOX as in nomad
But then I can add paint layer and import a regular image so it is wrapped on the object
I can export the object as OBJ and of course I have the separated file of the image
In nomad I can create an object and paint it, and also export the OBJ with a graphic image in zip (bake)
But can I do the reverse way? Import OBJ with graphics?

Normally, drag & drop of the OBJ zip file from the file app to the Nomad Sculpt viewport works. If the zip file is unpacked, import the parent folder with drag drop to Nomad.

The obj file format itself doesn’t store information about textures. In terms of materials, it can point to a .mtl file.

The mtl file has very limited support to tell other apps what to do with textures, but it should be enough for most cases. This is how nomad can tell procreate where to find textures, if you open the mtl file in a text editor, it looks like this:

# Exported from Nomad Sculpt

newmtl goblin
 map_Kd Tube_color.png
 map_roughness Tube_roughness.png
 map_metallic Tube_metalness.png

So I’d assume if mudbox can also export a mtl file alongside the obj, then nomad might be able to read it. If not, you’ll need to manually link the textures via the material menu Holger mentioned, which is also documented here: