求助matlab中rand函数问题
运行后出现如下的错误，请教大侠：Error using ==> rand
State must be a double scalar or the output of RAND('state').
Error in ==> cor_embed at 52
rand('state',key);
错误出在下面的红色部分
源程序：
%Name:
Chris Shoemaker
%Course:
EER-280 - Digital Watermarking
%Project:
Threshold-Based Correlation using block processing in the spatial domain
% Watermark embedding
clear all;
% save start time
start_time=cputime;
k=40; % set the gain factor for embeding
blocksize=16; % set the size of the block in cover to be used for each bit in watermark
% read in the cover object
file_name='_lena_std_bw.bmp';
cover_object=double(imread(file_name));
% determine size of watermarked image
Mc=size(cover_object,1);
%Height
Nc=size(cover_object,2);
%Width
% determine maximum message size based on cover object, and blocksize
max_message=Mc*Nc/(blocksize^2);
% prefilter the cover image with a matched filter to reduce detection errors
%prefilt=[-1,-1,-1;-1,10,-1;-1,-1,-1]./2;
%cover_object=filter2(prefilt,cover_object);
% read in the message image
file_name='_copyright.bmp';
message=double(imread(file_name));
Mm=size(message,1);
%Height
Nm=size(message,2);
%Width
% reshape the message to a vector
message=round(reshape(message,Mm*Nm,1)./256);
% check that the message isn't too large for cover
if (length(message) > max_message)
error('Message too large to fit in Cover Object.')
end
% pad the message out to the maximum message size with 0's
message_pad=ones(1,max_message);
message_pad(1:length(message))=message;
% read in key for PN generator
file_name='_key.bmp';
key=double(imread(file_name))./256;
% reset MATLAB's PN generator to state "key"
rand('state',key);
% generate the watermark equal to the size of one block
pn_sequence=round(2*(rand(blocksize,blocksize)-0.5));
% process the image in blocks
% first construct the global watermark mask
x=1;
y=1;
for (kk = 1:length(message_pad))
% if message bit contains zero, add PN sequence to that portion of mask
if (message_pad(kk) == 0)
watermark_mask(y:y+blocksize-1,x:x+blocksize-1) = pn_sequence;
% otherwise mask is filled with zeros
else
watermark_mask(y:y+blocksize-1,x:x+blocksize-1) = zeros(blocksize,blocksize);
end
% move to next block of mask along x; If at end of row, move to next row
if (x+blocksize) >= Nc
x=1;
y=y+blocksize;
else
x=x+blocksize;
end
end
% add watermark mask to cover image using gain factor k
watermarked_image_dbl=cover_object+k*watermark_mask;
watermarked_image_int=uint8(cover_object+k*watermark_mask);
% write the watermarked image out to a file
imwrite(watermarked_image_int,'cor_watermarked.bmp','bmp');
% display processing time
elapsed_time=cputime-start_time,
% calculate the PSNR
psnr=psnr(cover_object,watermarked_image_dbl,Mc,Nc),
% display watermarked image
figure(1)
imshow(watermarked_image_int,[])
title('Watermarked Image') 检查下LZ的key是否为一个值(scalar)?
页:
[1]