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Contrast Adjustment

Contrast adjustment, histogram equalization, decorrelation stretching

Contrast adjustment remaps image intensity values to the full display range of the data type. An image with good contrast has sharp differences between black and white.

To illustrate, the image on the left has poor contrast, with intensity values limited to the middle portion of the range. The image on the right has higher contrast, with intensity values that fill the entire intensity range [0, 255]. In the high contrast image, highlights look brighter and shadows look darker.

The functions described in this section apply primarily to grayscale images. However, some of these functions can be applied to color images as well. For information about how these functions work with color images, see the reference pages for the individual functions.

Image with poor contrast and narrow histogram versus image with high contrast and wide histogram.


imadjustAdjust image intensity values or colormap
imadjustnAdjust intensity values in N-D volumetric image
imcontrastAdjust Contrast tool
imsharpenSharpen image using unsharp masking
imflatfield2-D image flat-field correction
imlocalbrightenBrighten low-light image (Since R2019b)
imreducehazeReduce atmospheric haze
locallapfiltFast local Laplacian filtering of images
localcontrastEdge-aware local contrast manipulation of images
localtonemapRender HDR image for viewing while enhancing local contrast
histeqEnhance contrast using histogram equalization
adapthisteqContrast-limited adaptive histogram equalization (CLAHE)
imhistmatchAdjust histogram of 2-D image to match histogram of reference image
imhistmatchnAdjust histogram of N-D image to match histogram of reference image
decorrstretchApply decorrelation stretch to multichannel image
stretchlimFind limits to contrast stretch image
intlutConvert integer values using lookup table
imnoiseAdd noise to image