Image contrast enhancement techniques can be used in various image processing applications. There are various Image contrast enhancement techniques available. It depends on the particular type of image, which technique will prove better. Histogram equalization is one of the best technique that can be used for contrast enhancement. Different variants of Histogram equalization like Adaptive Histogram Equalization, Contrast Limited Adaptive Histogram equalization, Multiscale Adaptive Histogram Equalization, Dynamic Histogram Equalization, Partially overlapped sub-block Histogram Equalization, etc. can also be used. All these techniques mentioned proves good for a particular type of image, but they are not generalized methods which can be used for broad variety of images. A new method of contrast enhancement called as Gray level grouping (GLG) is suggested in this paper. GLG is a generalized method and can be used satisfactorily for broad variety of images. A variant of GLG, i. e. Adaptive Gray Level grouping (AGLG) is also discussed. [4]

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Gray level grouping (GLG) AHE MAHE CLAHE DHE POSHE low contrast images bins.