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demoEntropy.m
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%% load images and define qTable for Y and Cb/Cr %%
clear all; close all; clc
subimg = cell(1,3);
subimg{1} = [4 4 4]; subimg{2} = [4 2 2]; subimg{3} = [4 2 0];
qScale = [0.1 0.3 0.6 1 2 5 10];
load('img1_down.mat')
%~ Make the image to be exactly for blocks 8x8, whithout leftovers ~%
[N, M, ~] = size(img1_down); N = mod(N, 16); M = mod(M, 16);
img1_down = img1_down(1:end-N, 1:end-M, :);
load('img2_down.mat')
%~ Make the image to be exactly for blocks 8x8, whithout leftovers ~%
[N, M, ~] = size(img2_down); N = mod(N, 16); M = mod(M, 16);
img2_down = img2_down(1:end-N, 1:end-M, :);
%~ Define qTable for Y and Cb/Cr ~%
global qTableL qTableC;
[qTableL, qTableC] = changedTables(0);
%% Image 1 %%
tic
%~ For the Y component ~%
for i = 1:length(subimg) % for each resolution
curr_subimg = subimg{i};
for j = 1:length(qScale)
[imageY, imageCb, imageCr] = convert2ycbcr(img1_down, curr_subimg);
[RowNumberY, ColumnNumberY] = size(imageY);
allQuantY = []; allRunlengthY = [];
DC_PredY = 0;
for row = 1:8:RowNumberY
for column = 1:8:ColumnNumberY
blockY = imageY(row:row+7, column:column+7);
dctblockY = blockDCT(blockY);
quantblockY = quantizeJPEG(dctblockY, qTableL, qScale(j));
runSymbolsY = runLength(quantblockY, DC_PredY);
DC_PredY = quantblockY(1,1); % For the next iteration
allRunlengthY = [allRunlengthY; runSymbolsY];
allQuantY = [allQuantY quantblockY];
end
end
%~ For the Cb, Cr components ~%
[RowNumberCbCr, ColumnNumberCbCr] = size(imageCb);
allQuantCb = []; allQuantCr = [];
allRunlengthCb = []; allRunlengthCr = [];
DC_PredCr = 0; DC_PredCb = 0;
for row = 1:8:RowNumberCbCr
for column = 1:8:ColumnNumberCbCr
blockCr = imageCr(row:row+7, column:column+7);
blockCb = imageCb(row:row+7, column:column+7);
dctblockCr = blockDCT(blockCr);
dctblockCb = blockDCT(blockCb);
quantblockCr = quantizeJPEG(dctblockCr, qTableC, qScale(j));
quantblockCb = quantizeJPEG(dctblockCb, qTableC, qScale(j));
runSymbolsCr = runLength(quantblockCr, DC_PredCr);
runSymbolsCb = runLength(quantblockCb, DC_PredCb);
DC_PredCr = quantblockCr(1,1); % For the next iteration
DC_PredCb = quantblockCb(1,1); % For the next iteration
allRunlengthCb = [allRunlengthCb; runSymbolsCb]; allRunlengthCr = [allRunlengthCr; runSymbolsCr];
allQuantCb = [allQuantCb quantblockCb]; allQuantCr = [allQuantCr quantblockCr];
end
end
%~ Compute entropy for runlegth ~%
allRunlengths = [allRunlengthY; allRunlengthCb; allRunlengthCr];
%~ Find the unique rows ~%
[~, ~, icRuns] = unique(allRunlengths(:,1:2),'rows', 'stable');
%~ Count the freq of those rows in the runlengths ~%
freqRun = accumarray(icRuns, 1) / length(allRunlengths);
%~ Entropy is -freq*log(freq) ~%
entropyRunlength(i,j) = sum(-freqRun .* log2(freqRun)) * length(allRunlengths);
fprintf(['[First Image] ~ The entropy for the Runlength is: %e. [SubSampling %d:%d:%d], '...
'[qScale = %.2f].\n'], entropyRunlength(i,j), curr_subimg(1), curr_subimg(2), curr_subimg(3), qScale(j));
end
figure();
plot(qScale(:), entropyRunlength(i,:), '-o')
title_str = ['Entropy of Runlegths [SubSampling ', num2str(curr_subimg(1)), ':', num2str(curr_subimg(2)), ...
':', num2str(curr_subimg(3)), '] [First Image]'];
title(title_str, 'Interpreter', 'latex')
xticks(qScale(:))
xlabel('qScale', 'Interpreter', 'latex'); ylabel('Entropy', 'Interpreter', 'latex')
grid on
end
toc
%% Image 2 %%
%~ For the Y component ~%
tic
for i = 1:length(subimg) % for each resolution
curr_subimg = subimg{i};
for j = 1:length(qScale)
[imageY, imageCb, imageCr] = convert2ycbcr(img2_down, curr_subimg);
[RowNumberY, ColumnNumberY] = size(imageY);
allQuantY = []; allRunlengthY = [];
DC_PredY = 0;
for row = 1:8:RowNumberY
for column = 1:8:ColumnNumberY
blockY = imageY(row:row+7, column:column+7);
dctblockY = blockDCT(blockY);
quantblockY = quantizeJPEG(dctblockY, qTableL, qScale(j));
runSymbolsY = runLength(quantblockY, DC_PredY);
DC_PredY = quantblockY(1,1); % For the next iteration
allRunlengthY = [allRunlengthY; runSymbolsY];
allQuantY = [allQuantY quantblockY];
end
end
%~ For the Cb, Cr components ~%
[RowNumberCbCr, ColumnNumberCbCr] = size(imageCb);
allQuantCb = []; allQuantCr = [];
allRunlengthCb = []; allRunlengthCr = [];
DC_PredCr = 0; DC_PredCb = 0;
for row = 1:8:RowNumberCbCr
for column = 1:8:ColumnNumberCbCr
blockCr = imageCr(row:row+7, column:column+7);
blockCb = imageCb(row:row+7, column:column+7);
dctblockCr = blockDCT(blockCr);
dctblockCb = blockDCT(blockCb);
quantblockCr = quantizeJPEG(dctblockCr, qTableC, qScale(j));
quantblockCb = quantizeJPEG(dctblockCb, qTableC, qScale(j));
runSymbolsCr = runLength(quantblockCr, DC_PredCr);
runSymbolsCb = runLength(quantblockCb, DC_PredCb);
DC_PredCr = quantblockCr(1,1); % For the next iteration
DC_PredCb = quantblockCb(1,1); % For the next iteration
allRunlengthCb = [allRunlengthCb; runSymbolsCb]; allRunlengthCr = [allRunlengthCr; runSymbolsCr];
allQuantCb = [allQuantCb quantblockCb]; allQuantCr = [allQuantCr quantblockCr];
end
end
%~ Compute entropy for runlegth ~%
allRunlengths = [allRunlengthY; allRunlengthCb; allRunlengthCr];
%~ Find the unique rows ~%
[~, ~, icRuns] = unique(allRunlengths(:,1:2),'rows', 'stable');
%~ Count the freq of those rows in the runlengths ~%
freqRun = accumarray(icRuns, 1) / length(allRunlengths);
%~ Entropy is -freq*log(freq) ~%
entropyRunlength(i,j) = sum(-freqRun .* log2(freqRun)) * length(allRunlengths);
fprintf(['[Second Image] ~ The entropy for the Runlength is: %e. [SubSampling %d:%d:%d], '...
'[qScale = %.2f].\n'], entropyRunlength(i,j), curr_subimg(1), curr_subimg(2), curr_subimg(3), qScale(j));
end
figure();
plot(qScale(:), entropyRunlength(i,:), '-o')
title_str = ['Entropy of Runlegths [SubSampling ', num2str(curr_subimg(1)), ':', num2str(curr_subimg(2)), ...
':', num2str(curr_subimg(3)), '] [Second Image]'];
title(title_str, 'Interpreter', 'latex')
xticks(qScale(:))
xlabel('qScale', 'Interpreter', 'latex'); ylabel('Entropy', 'Interpreter', 'latex')
grid on
end
toc