Having a little photographic background, I have been playing around with trying to print out "images" with my i3. (easily...) I did print out an "image" last night that I thought turned out pretty cool.
We had an 8 x 10" photograph of my wife when she was a little girl. I scanned that with my regular flat bed scanner to get a .jpg of it. I found this article: Create Your Own 3D Printable Lithograph.... and made a .stl file of it.
Sliced it with .1mm layer height in Cura and slowed down the print speed a little. I started out with black PLA and let it print until I could see it was just beginning to print the image (first layer of what will show in the finished print), then paused the print and changed to "transparent" PLA. The "transparent" pla isn't 100% transparent so the more layers are printed, the more it turns to white, and less black shows through.
Playing around with a couple more images now.

3.jpg

4.jpg

2.jpg

1.jpg