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Archive Notice: This thread is old and no longer active. It is here for reference purposes. This thread was created on an older version of the flipcode forums, before the site closed in 2005. Please keep that in mind as you view this thread, as many of the topics and opinions may be outdated.
Shawn Swift

March 07, 2005, 07:33 PM

I have two images, and I need to make their brightnesses match. Computing the average of the first one and moving the second towards that is nice to get the average brightness correct, but I still need to scale the other brightnesses so they cover the same approximate range.

The only way that I seem to be able to find to do this is histogram matching. I think there is another name for that because I saw it once, but I forgot what it is, so I can't search for it.

Anyway, I need an easy to understand tutorial, or some source which explains how to do histogram matching, or ideas on how I might simply scale one image so that it has the same range of brightnessed statistically as another.


March 07, 2005, 09:31 PM

Sounds like what you're trying to do is match the contrast of each image. I don't know if that'll help you at all.

Rui Martins

March 08, 2005, 05:26 AM

Brightness and contrast are two different things.


Increasing brightness, makes the entire image more bright i.e. whiter, higher values in each color component (RGB).

Increasing Constrast, makes adjacent pixels with different (not similar) colors to increse that difference, and similar colro to become almost identical. i.e. the difference between their color components (RGB) is increased if it already exceeds some threshold and is decreased if they are already similar.

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