Resim Sıkıştırma ve Çözme ~ Ayrık Kosinus Dönüşümü

compress-decompress.m

function [J,N,K,D] = compress()

    f = double(rgb2gray(imread('g.png')));
    [R C] = size(f);
    
    J = zeros(R,C);
    N = zeros(R,C);
    D = {};
    K = {};

% Quantization 90    
%     Q = [3 2 2 3 5 8 10 12;
%          2 2 3 4 5 12 12 11;
%          3 3 4 5 8 11 14 11;
%          3 3 4 6 10 17 16 12;
%          4 4 7 11 14 22 21 15;
%          5 7 11 13 16 12 23 18;
%          10 13 16 17 21 24 24 21;
%          14 18 19 20 22 20 20 20];

% Quantization 10
%     Q = [80 60 50 80 120 200 255 255;
%      55 60 70 95 130 255 255 255;
%      70 65 80 120 200 255 255 255;
%      70 85 110 145 255 255 255 255;
%      90 110 185 255 255 255 255 255;
%      120 175 255 255 255 255 255 255;
%      245 255 255 255 255 255 255 255;
%      255 255 255 255 255 255 255 255];

% Quantization 50
    Q = [16 11 10 16 24 40 51 61;
         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];
    
    T = zeros(8,8);
    
    W = R/8;
    H = C/8;
    
    for a = 0:7
        for b= 0:7
            if a == 0
                T(a+1,b+1) = 1/sqrt(8);
            else
                T(a+1,b+1) = sqrt(2/8)*cos((((2*b+1)*a*pi)/(2*8)));
            end
        end
    end

    for r = 1:W
        for c = 1:H
            D{r,c} = round(discreate_cos(f(((r-1)*8 + 1):((r-1)*8 + 8),((c-1)*8 + 1):((c-1)*8 + 8)),T));
            K{r,c} = round(D{r,c}./Q);
            J(((r-1)*8 + 1):((r-1)*8 + 8),((c-1)*8 + 1):((c-1)*8 + 8)) = D{r,c};
        end
    end
    
    N = decompress(Q,T,K,N);
    
function D = discreate_cos(G,T)
    
    [X Y] = size(G);
    D = zeros(X,Y);
    
    M = G - 128;
    
    D = T*M*inv(T);
    
function N = decompress(Q,T,K,N)

    [R C] = size(N);
    W = R/8;
    H = C/8;
    
    for r = 1:W
        for c = 1:H
            R = Q.*[K{r,c}];
            N(((r-1)*8 + 1):((r-1)*8 + 8),((c-1)*8 + 1):((c-1)*8 + 8)) = round(inv(T)*R*T) + 128;
        end
    end