average color of colored blocks? or selected area > 11x11px?

[slothbear]

I have an image with dozens of colored squares, each representing a color of yarn. I'd like to get the average color of each color square.


I thought I used to use Effects/Pixelate, but now I can't get the effect to choose a single color.


The Eyedropper Tool with an 11x11 sample gets pretty close, but I have to fiddle around to find a spot that meets my subjective idea of the average color. If I could expand the sample size to the selected rectangle (50px by 50 px), that would be pretty close to what I want.

It would be ideal if I could apply one tool to the entire image and process all of the dozens of squares without processing each square individually. Effects/Gaussian Blur (at 6px) does a pretty good job, but there are still multiple colors.