POSHE 算法是在输入图像上定义一矩形子块,利用该子块图像的直方图信息对子块的所有像素进行直方图均衡化,将子块以一定的步长移动并重复以上处理过程,直至遍历输入图像的所有像素,对多次被均衡的像素,将均衡结果取平均作为该像素在输出图像中的灰度值。
下面的程序如何修改能够达到部分重叠的效果,图像运行后的白色的
clear;close all;clc;
str = 'lena.bmp';
I = imread(str);
figure,imshow(I),title('original image');
len = 5;
hstep = 2;
wstep = 2;
for k = 1:size(I,3)
img = I(:,:,k);
img = [img(:,len:-1:2) img img(:,end-1:-1:end-len)];
img = [img(len:-1:2,:) ;img; img(end-1:-1:end-len,:)];
[h w] = size(img);
med_out(:,:,k) = zeros(h,w);
counts = zeros(h,w);
for i =1:hstep:h
if h-i >= len
for j = 1:wstep:w
if w-j >= len
rect =histeq(img(i:i+len-1,j:j+len-1));%把图像块进行抛物线直方图均衡
med_out(i:i+len-1,j:j+len-1,k) = uint8(med_out(i:i+len-1,j:j+len-1,k))+rect;
counts(i:i+len-1,j:j+len-1) = counts(i:i+len-1,j:j+len-1)+1;
end
end
end
end
med_out1(:,:,k) = med_out(len+1:end-len-1,len+1:end-len-1,k);
med_out1(:,:,k) = med_out1(:,:,k)./counts(len+1:end-len-1,len+1:end-len-1);
out(:,:,k) = med_out1(:,:,k);
end
figure,imshow(out),title('poshe result');