Adaptive Histogram Equalization
As an alternative to using
histeq, you can perform contrast-limited
adaptive histogram equalization (CLAHE) using the
adapthisteq function. While
histeq works on the entire image,
adapthisteq operates on small regions in the image, called
adapthisteq enhances the contrast of each
tile, so that the histogram of the output region approximately matches a specified histogram.
After performing the equalization,
adapthisteq combines neighboring tiles
using bilinear interpolation to eliminate artificially induced boundaries.
To avoid amplifying any noise that might be present in the image, you can use
adapthisteq optional parameters to limit the contrast, especially in
Adjust Contrast using Adaptive Histogram Equalization
This example shows how to adjust the contrast in an image using CLAHE.
Read image into the workspace.
I = imread('pout.tif');
View the original image and its histogram.
figure subplot(1,2,1) imshow(I) subplot(1,2,2) imhist(I,64)
Adjust the contrast of the image using adaptive histogram equalization.
J = adapthisteq(I);
Display the contrast-adjusted image with its histogram.
figure subplot(1,2,1) imshow(J) subplot(1,2,2) imhist(J,64)