My exploration of photo manipulation tends to revolve around the relationship between color, texture, foreground, and background. I find it interesting that the slightest change in color or texture, or both, can drastically change the viewer's perception of what information is in the foreground and what information is in the background. Additionally, how combinations of colors can create varying textures.
Lips
Adobe Photoshop
This image is a tessellated image of lips, emphasizing their shape and texture.