Index in position 2 exceeds array bounds. (reason for error)

img=imread('D:/lena1.png');
[height, width]=size(img);
for a=1:8:height
    disp(height);
    for b=1:8:width
        imgdct_8(a:a+7,b:b+7)=dct2(img(a:a+7,b:b+7));
    end
end
for i=1:8
    for j=1:8
        qtz_mtrx(i,j)=1+((i+j)* 15);
    end
end

[lakshmi amruthavalli P]

someone help this, please

Answer 1

[Walter Roberson]

[height, width]=size(img);

You are probably thinking that code is the same as

temp = size(img) ;
height = temp(1);
width = temp(2);

But it is not the same. Instead it means

temp = size(img);
height = temp(1);
width = prod(temp(2:end));

This matters because lena1.png is a color image, so your width ends up being 3 times what you expect.

[lakshmi amruthavalli P]

thank you so much

[lakshmi amruthavalli P]

what change should i do in the code... suggest me