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The equalized histogram looks like the original histogram, although it has been "stretched" across the entire spectrum. The cumulative frequency graph shows the (almost) linear nature of grey level frequencies within the image. Note that the same process can be applied to colour images by performing the process on the red, green and blue channels separately as this image shows: If you want to experiment further, this article was written using the Generation5 JDK's Histogram and EqualizeFilter classes (although the JDK's builtin histogram visualization was not used, since Gnuplot provided nicer looking results). ReferencesEfford, Nick. Digital Image Processing: A Practical Introduction Using Java. AddisonWesley. Essex: 2000.
Submitted: 26/11/2004 Article content copyright © James Matthews, 2004.


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