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Test_2D_DCT.asv
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Test_2D_DCT.asv
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% =======================================================================
% Advanced Multimedia Applications
% Name : 2D_DCT_Test.m
% Description : Test Script for 2D_DCT.
% =======================================================================
clc;clear;close all;
%=====================================================================
% T E S T - S C R I P T P A R A M E T E R S
%=====================================================================
img = imread('lena512.bmp');
imshow(img);
% img = imread('Cameraman.bmp');
% imshow(img);
img = double(img)-128;
[m,n] = size(img);
b = 8;
num_blocks = (m*n)/(b*b);
num_hor_blks = m/b;
num_ver_blks = n/b;
speed = 0; % 0-simple dct, 1-fast dct
%=====================================================================
% INITIALISATION
%=====================================================================
% split the input larger matrix into smaller 8x8 blocks
split_img = mat2cell(img, b*ones(m/b,1), b*ones(1,n/b));
% subplot index
sp=1;
%=====================================================================
% DISCRETE COSINE TRANSFORM
%=====================================================================
tstart = tic;
% perform DCT --> IDCT for each block
for i = 1:num_ver_blks
for j = 1:num_hor_blks
% --------------- 2D-DCT -------------------------------------
% perform DCT - Encoder side
% (output is a array of cells)
enc_dct_block = dct_2_8x8(split_img{i,j},b,speed)';
% block = split_img{i,j};
%
% enc_dct_block = dct2(block,b,speed);
%
test_enc_dct_block{i,j} = enc_dct_block;
%=====================================================================
% INVERSE - DISCRETE COSINE TRANSFORM
%=====================================================================
% --------------- 2D - Inverse - DCT -------------------------
dec_idct_block{i,j} = idct_2_8x8(enc_dct_block,b, speed)';
reconstructed_cell{i,j} = dec_idct_block{i,j};
%display(['Finished Decoding block=',num2str(i),',',num2str(j)])
end
end
telapsed = toc(tstart)
% convert the array of cells back to a matrix
reconstructed_img = cell2mat(reconstructed_cell);
% add back the 128, and convert to uint8 (to be displayed)
reconstructed_img = reconstructed_img + 128;
reconstructed_img = uint8(reconstructed_img);
% display reconstructed picture
figure;imshow(reconstructed_img);
%imshow(abs(split_img{1,1}));
%=====================================================================
% OUTPUT TEST RESULTS
%=====================================================================
% --- work on block :(15,15) ---
i=15;j=25;
% original block matrix
img_block = split_img{i,j}
% output of 2D-DCT
dct_2_8x8 = test_enc_dct_block{i,j}
% print out basic transform output
dct_2_simple = dct_2_simple(split_img{i,j})
% output of 2D-IDCT
idct_2_8x8 = round(dec_idct_block{i,j})
% are they equal ??
img_block == idct_2_8x8
% subplot all the dct blocks
for i = 200:210
for j = 200:210
subplot(5,5,sp);
imshow(abs(test_enc_dct_block{i,j}));
sp=sp+1;
display(['Finished plotting block=',num2str(i),',',num2str(j)])
end
end
figure;sp=1;
% subplot all the dct blocks
for i = 200:209
for j = 200:209
subplot(10,10,sp);
imshow(uint8(split_img{i,j}+128));
sp=sp+1;
display(['Finished plotting block=',num2str(i),',',num2str(j)])
end
end