matlab练习程序（彩虹编码伪彩色化）

cl;
img=imread('fupeng.jpg');
z=3;
[x y]=size(img);
imshow(img);
img=double(img);
img_cai=zeros(x,y,z);
Max=max(max(img));
Min=min(min(img));
img=(255/(Max-Min))*img-(255*Min)/(Max-Min);
figure,imshow(uint8(img));
r=1;
g=2;
b=3;

for i=1:x
for j=1:y
        temp=(2*pi/(Max-Min))*img(i,j)-(2*pi*Min)/(Max-Min);       

if temp<=pi/2
            img_cai(i,j,r)=0;
            img_cai(i,j,g)=0;
            img_cai(i,j,b)=255*(sin(temp));
end

if temp>pi/2 && temp<=pi
            img_cai(i,g,r)=0;
            img_cai(i,j,g)=255*(-cos(temp));
            img_cai(i,j,b)=255*(sin(temp));
end

if temp>pi && temp<=pi*3/2
            img_cai(i,j,r)=255*(-sin(temp));
            img_cai(i,j,g)=255*(-cos(temp));
            img_cai(i,j,b)=0;
end

if temp>pi*3/2
            img_cai(i,j,r)=255*(-sin(temp));
            img_cai(i,j,g)=0;
            img_cai(i,j,b)=0;     
end

     %   img_cai(i,j,1)=127.5*(-sin(temp))+127.5;
     %   img_cai(i,j,2)=127.5*(-cos(temp))+127.5;
     %   img_cai(i,j,3)=127.5*(sin(temp))+127.5;        
end
end

figure,imshow(uint8(img_cai));