867249 - Improve BitmapUtils.getDominantColor to avoid returning gray-ish colors

Status: RESOLVED FIXED

Description

[:Margaret Leibovic]

We are already trying to do this, but still failing in some cases. A few testcases that return a shade of gray instead of a color:
http://www.cnn.com/favicon.ico
http://boingboing.net/favicon.ico
http://www.amazon.com/favicon.ico

The first two are very red, so I wonder if we're doing something wrong with red hues. The third one is more about ignoring gray tones to return the dominant non-gray color.

There's some JS code in toolkit that looks a lot more complicated than what we're currently doing, maybe we can steal some ideas:
http://mxr.mozilla.org/mozilla-central/source/toolkit/components/places/ColorAnalyzer_worker.js

See also bug 634139.

Comment 1

[Wesley Johnston (:wesj)]

Bug 826780 also has some improvements we should take.

Comment 2

[:Margaret Leibovic]

Attachment: Clean up getDominantColor logic

So the problem with the red favicons is actually a bug with red. If maxH is 0 (red), we never end up updating maxS and maxV to return the correct color.

Looking through this code, I noticed that we don't actually do anything with sat or val, and we only keep track of maxS and maxV to put a color back together, so I decided to streamline the logic. We may want to actually compute S and V values for the dominant color in the future, but this just clarifies our current behavior.

I also found that the logic to skip black and white values was slightly off. We should be using an || instead of an &&. Fixing this returns yellow for the amazon.com logo.

Comment 3

[:Margaret Leibovic]

Attachment: Clean up getDominantColor logic

Oops, most recent changes didn't make it in here.

Comment 4

[Wesley Johnston (:wesj)]

Comment on attachment 743869 [details] [diff] [review]
Clean up getDominantColor logic

Review of attachment 743869 [details] [diff] [review]:
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This makes me nervous (but I know the old algorythm was prone to problems). Can you test a few webapps and see how we do (this should fix some bugs there too!)

Comment 5

[:Margaret Leibovic]

Attachment: Improved patch

This patch does what the patch in bug 826780 was trying to do, keeping track of the average hue/saturation/value per bin, then using that to compute the dominant color that we return.

This patch also still fixes the bugs I mentioned in previous comments.

Comment 6

[:Margaret Leibovic]

Attachment: Even more improved patch

Comment 7

[Brian Nicholson (:bnicholson)]

Comment on attachment 744306 [details] [diff] [review]
Even more improved patch

Review of attachment 744306 [details] [diff] [review]:
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Nice fixes.

Comment 8

[:Margaret Leibovic]

https://hg.mozilla.org/integration/mozilla-inbound/rev/b036d96c4c87

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/b036d96c4c87