imgjpeg

function out = imgjpeg(file,p)
%file must be square
%Some parts of code obtained from
%http://math.gmu.edu/~tsauer/class/447/proj/chap11.pdf

Q = p*[16 11 10 16 24 40 51 61  %JPEG quantization matrix
     12 12 14 19 26 58 60 55
     14 13 16 24 40 57 69 56
     14 17 22 29 51 87 80 62
     18 22 37 56 68 109 103 77
     24 35 55 64 81 104 113 92
     49 64 78 87 103 121 120 101
     72 92 95 98 112 100 103 99]

X = imread(file); % assign the image to X

X = double(X);    % convert to double
r = X(:,:,1);
g = X(:,:,2);
b = X(:,:,3);

X = 0.216*r + 0.7152*g + 0.0722*b; %converts to grey

[m,n] = size(X);                   %creates sublist to perform loops

for i = 1:8:m
    for j = 1:8:n

        block = X(i:i+7,j:j+7);    % take 8x8 block
        comp = imagecomp(block,Q); % compress the block
        X(i:i+7,j:j+7) = comp;     % insert the block back in

    end
end

% show the newly compressed image
figure
imagesc(uint8(X)); colormap(gray)

title(['P = ', num2str(p)])

out = X;

Not enough input arguments.

Error in imgjpeg (line 6)
Q = p*[16 11 10 16 24 40 51 61  %JPEG quantization matrix