图像增强：直方图均衡和小波变换【matlab】

　　直方图均衡：统计图像像素灰度的直方图分布。对其进行重新分配以使图像的直方图分布更加均衡。

小波变换：图像轮廓主要体现在低频部分，可以通过对低频分解系数进行增强处理，对高频分解系数进行衰减处理，达到图像增强。

clc;
clear all;
img=imread('D:\文件及下载相关\图片\gray.jpg');
gray_img=rgb2gray(img);
[m,n]=size(gray_img);
pr=zeros(,);
for i=:
     pr(i)=length(find(gray_img==i-))/(m*n);
end
S=zeros(,);
for i=:
     for j=:i
          S(i)=pr(j)+S(i);
     end
end
S1=round((S*)+0.5);
for i=:
     q(i)=sum(pr(find(S1==i)));
end
res_img=gray_img;
for i=:
    res_img(find(gray_img==i-))=S1(i);
end
imshow(res_img);
title('均衡化后');

小波变换：

clc
I= imread('D:\文件及下载相关\图片\gray.jpg');
I1 = I(:,:,);
[c,s]=wavedec2(I1,,'sym4'); len=length(c);
w = prod(s(,:));
for i =:w
    if(c( i )>)
      c( i )=1.3*c( i );
    end
end
for i =w:len
    if(c( i ) < )
      c( i )=0.8*c( i );
    end
end
nx1=waverec2(c,s,'sym4');
I2 = I(:,:,);
[c,s]=wavedec2(I2,,'sym4');
len=length(c);
w = prod(s(,:));
for j =:w
    if(c( j )>)
      c( j )=1.3*c( j );
    end
end
for j =w:len
    if(c( j ) < )
      c( j )=0.8*c( j );
    end
end
nx2=waverec2(c,s,'sym4'); I3 = I(:,:,);
[c,s]=wavedec2(I3,,'sym4');
len=length(c);
w = prod(s(,:));
for k =:w
    if(c( k )>)
      c( k )=1.3*c( k );
    end
end
for k =w:len
    if(c( k ) < )
      c( k )=0.8*c( k );
    end
end
nx3=waverec2(c,s,'sym4');
nx = cat(,nx1,nx2,nx3);
figure(),imshow(nx/)