Feature requests to improve readability

[lgarczyn]

I thought a bit since I read the article, and thought of ways to improve the results:

• Not increasing the intensity of the background color. On a few example pictures the background becomes garish and over-saturated.

• Using the CIE color space for clustering. It is much more accurate for calculating perceived color distance, and will result in superior clustering. CIE is implemented by the colormath library.

• Using a walking median to calculate the background color. Could be done individually by color. Would result in a background color not stripped of the least significant bits.