I don't know this watermarking code~ please explain code~

Question

DoSeok Lee 2015-6-29

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/225743-i-don-t-know-this-watermarking-code-please-explain-code

编辑： Walter Roberson 2015-6-29

clc
close all
%host
rgbimage=imread('host.jpg');
figure;imshow(rgbimage);title('original color image');
[h_LL,h_LH,h_HL,h_HH]=dwt2(rgbimage,'haar');
dec2d = [... 
        h_LL,     h_LH;     ... 
        h_HL,     h_HH      ... 
        ];
figure,imshow(uint8(dec2d));title('DWT2 of original color image');
%watermark
rgbimage=imread('watermark.jpg');
figure;imshow(rgbimage);title('Watermark image');
[w_LL,w_LH,w_HL,w_HH]=dwt2(rgbimage,'haar');
dec2d = [... 
        w_LL,     w_LH;     ... 
        w_HL,     w_HH      ... 
        ];
figure,imshow(uint8(dec2d));title('DWT2 of Watermark image');
%watermarked
rgbimage=imread('watermarked.jpg');
figure;imshow(rgbimage);title('Watermarked image');
[wm_LL,wm_LH,wm_HL,wm_HH]=dwt2(rgbimage,'haar');
dec2d = [... 
        wm_LL,     wm_LH;     ... 
        wm_HL,     wm_HH      ... 
        ];
figure,imshow(uint8(dec2d));title('DWT2 of Watermarked image');
%watermarking
newwatermark_LL= (wm_LL-h_LL)/0.30;
%extracted watermark image
rgb2=idwt2(newwatermark_LL,w_LH,w_HL,w_HH,'haar');
figure;imshow(uint8(rgb2));title('Extracted watermark');
imwrite(uint8(rgb2),'EWatermark.jpg');
-----------------------------------------------------------------

someone sent this watermarking sourece to me

but I don't understand this code~

I wonder these part matlab source~

%host rgbimage=imread('host.jpg');%<-- example I insert image cameraman.tif (my file name)256x256
%watermark rgbimage=imread('watermark.jpg'); %<-- exmaple I insert image rice.tif (my file name)256x256
%watermarked rgbimage=imread('watermarked.jpg'); <-- I don't know what kind of image insert?