Error using round(resh​ape(messag​e,Mm*Nm,1)​./256)

Hello,

What may be the problem with the following code line?

message=round(reshape(message,Mm*Nm,1)./256); using this I want to check message isn't too large to fit in cover image.

Where message=double(imread('lena.jpg')) and [Mm Nm] is the size of the message.

Thanks in advance

Answer 1

[James Tursa]

What does the error message say?

Double check the size of the variable message to make sure it really is Mm x Nm.

Note that you can replace reshape(message,Mm*Nm,1) with message(:)

[vaishali]

Thank you for your fast response .

The error says "To RESHAPE the number of elements must not change."

And this is the code segment

close all;
clear;
   cover = imread('cheeta.jpg');    
    [a1 h1 v1 d1] = dwt2(cover,'haar');
    [a2 h2 v2 d2] = dwt2(h2,'haar');

    k=50;           % set minimum coeff difference
    blocksize=8;    % set the size of the block in cover to be used for each bit in    watermark    
    cover_object=h2;
    %figure,imshow(cover);title('Original');    % determine size of cover image
    Mc=size(cover_object,1);          %Height
    Nc=size(cover_object,2);
    % determine maximum message size based on cover object, and blocksize
    max_message=Mc*Nc/(blocksize^2);    % read in the message image
    msg='lena.jpg';
    message=double(imread(msg));
    Mm=size(message,1);                  %Height
    Nm=size(message,2);                  %Width    % reshape the message to a vector
   message=round(reshape(message,Mm*Nm,1)./256);

[James Tursa]

What is size(message)? In particular, what is size(message,3)?

Answer 2

[Roger Stafford]

Does 'lena.jpg' produce a third dimension for color? If so, that would account for your error message; you would have more than Mm*Nm elements in 'message'.