直方圖均衡結果

Question

我想通過我自己對直方圖均衡進行編碼，但結果與matlab histeq中的內置函數不同。任何建議爲什麼會發生這種情況？我附上了代碼和結果。

%% 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,[]); 

Answer 1

histeq默認使用64個箱，以均衡的直方圖。您正在使用默認實現histeq。試試看：

builtInEqualizationI = histeq(grayI, 256); 

...指定256個bin用於均衡，因爲您的手動代碼正在使用該許多bin進行均衡。第二個參數將覆蓋默認值，並通知histeq使用該許多分檔執行均衡。