Short Description

Enhances the global contrast by equalizing the histogram. This plugin transforms pixel intensities so that they are uniformly distributed over the gray-scale range. It operates on the selected channel of each image of a sequence. This operation is also called "histogram flattening".
Wikipedia entry on histogram equalization: http://en.wikipedia.org/wiki/Histogram_equalization

Documentation

Equalizing the histogram of an image is an operation on the pixel intensities aimed at enhancing the global contrast. The algorithm tries to transform the intensities so that they are uniformly distributed over the gray-scale range. It works by computing the cumulative intensity distribution of the image, and replace pixel intensities by their index in this distribution. The operation is nonlinear, so it can produce images that look unrealistic.

This plugin operates on a single channel of each single image of a sequence. Equalization of the luminance of a colored image is not possible yet.

This method has been generalized in various ways. See the Adaptative histogram equalization plugin for a context-dependant variant.

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2 reviews on “Histogram Equalization”

  1. A
    Avery nice plugin with strong capabilities.
  2. s
    Excellent, will be greatly used.

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Changelog

  • Version 1.0.0.7 • Released on: 2012-06-21 09:23:03
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    Description:

    Provide a Blocks interface to use the Histogram equalization in the visual programming environment.

  • Version 1.0.0.6 • Released on: 2012-06-14 11:02:39
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    Description:

    Oops, previous jar was exported from wrong source branch...

  • Version 1.0.0.5 • Released on: 2012-06-14 10:58:54
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    Description:

    Use the continuous version of the algorithm even for integer-type sequences. The continuous version is much more memory-savy

  • Version 1.0.0.4 • Released on: 2012-02-22 09:26:18
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    Description:

    Rebuild for EzPlug ABI changes.

  • Version 1.0.0.3 • Released on: 2012-02-09 11:27:41
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    Description:

    Fix the missing lower bound for the channel index selector.

  • Version 1.0.0.2 • Released on: 2012-02-08 13:40:07
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    Description:

    - Rebuild for EzPlug/Vars library changes
    - Fix the detection of float data types

  • Version 1.0.0.1 • Released on: 2011-06-21 10:02:12
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    Description:

    Fix the channel selector.

  • Version 1.0.0.0 • Released on: 2011-06-20 17:01:59
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    Description:

    Initial version.