wvanbergen/oily_png — pull request #11 by lencioni (2014-04-14 17:43:47+00:00)
Title: Add euclidean_distance_rgba

This method was recently added to ChunkyPNG[1]. From that commit
message:

This method simply takes the Euclidean distance between the RGBA
channels of 2 colors, which gives us a measure of how different the
two colors are.

Although it would be more perceptually accurate to calculate a proper
Delta E in Lab colorspace, this method should serve many use-cases
while avoiding the overhead of converting RGBA to Lab.

This commit adds the C implementation of this method to OilyPNG.

[1]: wvanbergen/chunky_png@6e350b2

Note that the specs won't pass until a new version of ChunkyPNG with
`euclidean_disatance_rgba` is released, and OilyPNG is updated to
depend on this version.