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How to find the dominant/most common color in an image?

Asked 2010-07-13T22:05:55.877
108

I'm looking for a way to find the most dominant color/tone in an image using python. Either the average shade or the most common out of RGB will do. I've looked at the Python Imaging library, and could not find anything relating to what I was looking for in their manual, and also briefly at VTK.

I did however find a PHP script which does what I need, here (login required to download). The script seems to resize the image to 150*150, to bring out the dominant colors. However, after that, I am fairly lost. I did consider writing something that would resize the image to a small size then check every other pixel or so for it's image, though I imagine this would be very inefficient (though implementing this idea as a C python module might be an idea).

However, after all of that, I am still stumped. Is there an easy, efficient way to find the dominant color in an image?

python image image-processing colors
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2 Answers

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You could use PIL to repeatedly resize the image down by a factor of 2 in each dimension until it reaches 1x1. I don't know what algorithm PIL uses for downscaling by large factors, so going directly to 1x1 in a single resize might lose information. It might not be the most efficient, but it will give you the "average" color of the image.

answered 2010-07-13T23:46:57.827
4

To add to Peter's answer, if PIL is giving you an image with mode "P" or pretty much any mode that isn't "RGBA", then you need to apply an alpha mask to convert it to RGBA. You can do that pretty easily with:

if im.mode == 'P':
    im.putalpha(0)
answered 2011-01-27T03:52:51.720

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