Adaptive histogram equalization

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Adaptive histogram equalization (AHE) is a computer image processing technique used to improve contrast in images. It differs from ordinary histogram equalization in the respect that the adaptive method computes several histograms, each corresponding to a distinct section of the image, and uses them to redistribute the lightness values of the image. It is therefore suitable for improving the local contrast and enhancing the definitions of edges in each region of an image. However, AHE has a tendency to overamplify noise in relatively homogeneous regions of an image. A variant of adaptive histogram equalization called contrast limited adaptive histogram equalization (CLAHE) prevents this by limiting the amplification.

Read on Wikipedia · Image File:BLM using satellites to study fishers in southern Oregon (27691391805).jpg: Bureau of Land Management Oregon and Washington from Portland, America derivative work: SreySros, CC BY 4.0