直方图均衡结果

I am trying to code histogram equalization by my self, but the results are different from the built in function in matlab histeq. Any suggestions why is this happening?. I attached the code and the results.

%% Histogram Equalization
close all
clear all
%%
I = imread('Iris_virginica.jpg');
grayI = rgb2gray(I);
[m,n] = size(grayI);
L = 256;
[counts,x] = imhist(grayI);
myCDF = cumsum(counts)/(m*n);
equalizedI = (L-1)*myCDF(double(grayI)+1);
equalizedI = uint8(equalizedI);
histMyOut = imhist(equalizedI);
builtInEqualizationI = histeq(grayI);
histBuiltInEqu = imhist(builtInEqualizationI);
%%
figure
subplot(1,3,1), stem(x,counts), title('Histogram');
subplot(1,3,2), stem(x,myCDF), title('Commulative Distribution');
subplot(1,3,3), stem(x,imhist(equalizedI)), title('Equalized');

figure
subplot(1,3,1),imshow(grayI), title('Input image');
subplot(1,3,2), imshow(equalizedI), title('Equalized image (mine)');
subplot(1,3,3), imshow(builtInEqualizationI), title('Equalized image (matlab)');

figure
subplot(1,3,1), stem(x,counts), title('Histogram');
subplot(1,3,2), stem(x,histMyOut), title('Equalized Histogram (mine)');
subplot(1,3,3), stem(x,histBuiltInEqu), title('Equalized Histogram (matlab)');

difference = abs(equalizedI-builtInEqualizationI);
figure, imshow(difference,[]);

histeq默认情况下使用 64 个 bin 来均衡直方图。您正在使用默认实现histeq。尝试做：

builtInEqualizationI = histeq(grayI, 256);

...指定 256 个 bin 进行均衡，因为您的手动代码正在使用那么多 bin 进行均衡。第二个参数覆盖默认值并通知histeq使用那么多的 bin 来执行均衡。