Method: Diffux::SnapshotComparisonImage::Base#pixel_diff_score

Defined in:
lib/diffux_core/snapshot_comparison_image/base.rb

#pixel_diff_score(pixel_after, pixel_before) ⇒ Float

Compute a score that represents the difference between 2 pixels

This method simply takes the Euclidean distance between the RGBA channels of 2 colors over the maximum possible Euclidean distance. This gives us a percentage of how different the two colors are.

Although it would be more perceptually accurate to calculate a proper Delta E in Lab colorspace, we probably don't need perceptual accuracy for this application, and it is nice to avoid the overhead of converting RGBA to Lab.

Parameters:

  • pixel_after (Integer)
  • pixel_before (Integer)

Returns:

  • (Float) —

    number between 0 and 1 where 1 is completely different and 0 is no difference



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# File 'lib/diffux_core/snapshot_comparison_image/base.rb', line 84

def pixel_diff_score(pixel_after, pixel_before)
  ChunkyPNG::Color::euclidean_distance_rgba(pixel_after, pixel_before) /
    ChunkyPNG::Color::MAX_EUCLIDEAN_DISTANCE_RGBA
end