Modifying UV Materials

[Asterlil]

In this image you can see a section of a tiled floor where all the tiles were separate objects colored red, tawny and black. To reduce the file size of the model, I created an image and UV mapped it onto the rest of the terraces. It worked pretty well, just a little less crisp. But, as you see from the other parts of the terrace, the map is now suffused with red. The UV map of the tile pattern is also attached (help yourselves!) so you can see how the color has changed.

Can I modify the color balance of a shader node in Terragen?
If so, is there a tutorial available?
If no tutorial and modification is possible, could somebody tell me what to do in nice easy steps?
If modification isn't possible, I'll have to rebuild all the terraces around the building, which will be lots of extra work...

(The pattern is "hidden lion" from the book Pilgermann by Russell Hoban. I created it from his prose description and rudimentary sketches.)

[Dune]

With a color adjust you can change individual channels RGB. Secondly; for a repetitive pattern like shown, your file can be much smaller again. You can cut out just a few of those patches (like shown, approximately); when tiled in TG they would make it infinite again.
Furthermore, if you set up the basic smaller area of just a few triangles, you can do so at a slightly bigger scale, and subtly blur it, so the pattern isn't so crisp. Only thing you'd have to make it again from scratch, as the jpg is not very tight when enlarged, and has artifacts.

[Hannes]

Do the parts that still appear red have another shader than the correctly displayed ones? If so, maybe the diffuse color is still set to red, so even if you apply a texture, the shader is tinted by the diffuse color. Make sure it's set to white.

[Asterlil]

I should have posted earlier, if only to say, "I am just stepping out and may be some time," but I did become deeply involved in fixes and enhancements to the original model. @Hannes, I didn't realize that the color (yes, the default non-texture color) would have an effect on the image map, and appreciate the guidance on that. @Dune, well pointed out about the quality of the image map. I wound up going back to the model and recreating the pattern as a mesh, then propagating that. I was extremely surprised when the consequence of that was a substantial reduction in the size of the OBJ file.

And now to place the model back in Terrahen and start landscaping.