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histogram equalization

A point operation that spreads out an image's intensity values to use the full range as evenly as possible.

Histogram equalization derives a point operation from the image's own cumulative histogram, spreading out crowded intensity values and compressing sparse ones so the output histogram is as close to flat (uniform) as the discrete pixel values allow -- a near-automatic contrast-enhancement preprocessing step.

See also

cumulative histogram histogram matching (specification)
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