All codes

Author: cxy1997

Project 1/Problem1.pdf

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+clc;clear;
+%% Write a computer program for computing the histogram of an image.
+fig1 = imread('data/Fig1.jpg');
+fig2 = imread('data/Fig2.jpg');
+figure('Name', 'Original Histogram');
+set(gcf, 'position', [0 0 1024 512]);
+subplot(1, 2, 1);
+[L1 D1] = myImhist(fig1);
+title('Fig 1');
+subplot(1, 2, 2);
+[L2 D2] = myImhist(fig2);
+title('Fig 2');
+
+%% Implement the histogram equalization technique.
+figure('Name', 'Transformation of Fig. 1');
+set(gcf, 'position', [0 0 960 512]);
+subplot(1, 2, 1);
+imshow(fig1, []);
+R1 = myEqualization(L1, D1);
+for i = 1:size(fig1, 1)
+    for j = 1:size(fig1, 2)
+        fig1(i, j) = R1(fig1(i, j) + 1);
+    end
+end
+subplot(1, 2, 2);
+imshow(fig1, []);
+
+figure('Name', 'Transformation of Fig. 2');
+set(gcf, 'position', [0 0 1024 512]);
+subplot(1, 2, 1);
+imshow(fig2, []);
+R2 = myEqualization(L2, D2);
+for i = 1:size(fig2, 1)
+    for j = 1:size(fig2, 2)
+        fig2(i, j) = R2(fig2(i, j) + 1);
+    end
+end
+subplot(1, 2, 2);
+imshow(fig2, []);
+
+figure('Name', 'Transformation Function');
+subplot(1, 2, 1);
+plot(R1);
+subplot(1, 2, 2);
+plot(R2);
+
+figure('Name', 'Equalized Histogram');
+set(gcf, 'position', [0 0 1024 512]);
+subplot(1, 2, 1);
+[L1 D1] = myImhist(fig1);
+%title('Fig 1');
+subplot(1, 2, 2);
+[L2 D2] = myImhist(fig2);
+%title('Fig 2');

Project 1/src/Histogram_Equalization.m

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+function [ output_distribution ] = myEqualization( L, distribution )
+%MYEQUALIZATION equalizes the histogram
+%   It returns a mapping that equalizes the original distribution
+
+    output_distribution = distribution;
+    for i = 2:size(distribution);
+        output_distribution(i) = output_distribution(i-1) + distribution(i);
+    end
+    output_distribution = output_distribution * (L - 1) / sum(distribution(:));
+
+
+end
+

Project 1/src/data/Fig1.jpg

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+function [ L, distribution ] = myImhist( fig )
+%MYIMHIST creates the histogram of a given image.
+%   The function returns the number of pixels for each gray level, 
+%   and draws a figure automatically.
+    L = 8;
+    if L <= max(max(fig))
+        L = 256;
+    end
+    distribution = zeros(L, 1);
+    for i = 1:size(fig, 1)
+        for j = 1:size(fig, 2)
+            distribution(fig(i, j) + 1, 1) = distribution(fig(i, j) + 1, 1) + 1;
+        end
+    end
+    % distribution = table(:, 2);
+    distribution = distribution ./ size(fig, 1) ./ size(fig, 2)
+    s = size(distribution);
+    b = bar(distribution,'FaceColor', 'blue', 'EdgeColor', 'blue','LineWidth',0.6);
+    set(gca,'XLim',[0 L]);
+    set(gca,'XTick',[0:L/4:L]);
+    set(gca,'XTickLabel',[0:L/4:L]);
+    ylabel('Occurance');
+    colormap(gray);
+    c = colorbar('Location', 'southoutside', 'FontSize',10, 'Ticks', 0:64:256, 'TickLabels', {'0', '64', '128', '192', '256'});
+    c.Label.String = 'Intensity';
+    
+
+end
+