Texture Painting - Blender Master Class: A Hands-on Guide to Modeling, Sculpting, Materials, and Rendering - page 161

Before curves After curves

Figure 11-11: Incorporating the ambient occlusion map into our texture. Top left: The ambient occlusion texture multiplied over
the rough diffuse texture at 40 percent opacity, before any alteration. Bottom: Adjusting the colors of the ambient occlusion map
with the Curves tool, to make it redder. Top right: The reddened ambient occlusion map multiplied over the diffuse texture at
40 percent opacity.