color enhancement using histogram

Question

Maryam Al-Muhaini 2019-12-18

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/497265-color-enhancement-using-histogram

回答： Image Analyst 2019-12-20

I keep getting black and white pic while my purpose is to enhance the color using the average of histograms

this is my coe

X = im2double(imread('Capture.jpg'));
R = X(:,:,1);
G = X(:,:,2);
B = X(:,:,3);
z = zeros(size(R));
Rimg = cat(3, R, z, z);
Gimg = cat(3, z, G, z);
Bimg = cat(3, z, z, B);
L256 = linspace(0,1,256).';
z256 = zeros(256,1);
mapR = [L256, z256, z256];
mapG = [z256, L256, z256];
mapB = [z256, z256, L256];
figure,
subplot(2,2,1),image(Rimg); colormap(mapR); 
subplot(2,2,2),image(Gimg); colormap(mapG); 
subplot(2,2,3),image(Bimg); colormap(mapB); 
counts1=histeq(R);
counts2=histeq(G);
counts3=histeq(B);
figure,
subplot(2,2,1),imshow(counts1);
subplot(2,2,2),imshow(counts2);
subplot(2,2,3),imshow(counts3);
mean_counts = mean([counts1(:), counts2(:), counts3(:)],2);
figure, plot(mean_counts)%average
J= histeq(X, mean_counts);%itf 
r= histeq(R,mean_counts);
g= histeq(G,mean_counts);
b= histeq(B,mean_counts);
figure,
subplot(2,2,1),imshow(X);
subplot(2,2,2),imshow(r);
subplot(2,2,3),imshow(g);
subplot(2,2,4),imshow(b);

2 个评论
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KALYAN ACHARJYA 2019-12-18

n1??

Maryam Al-Muhaini 2019-12-18

fixed it. any help?

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Answer 1

KALYAN ACHARJYA 2019-12-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/497265-color-enhancement-using-histogram#answer_406948

编辑：KALYAN ACHARJYA 2019-12-18

It's not black and white image, the resultant also RGB image, see the data types. When I have tried with different image. The color of an image is just a perception, how it looks, mathematically it may not be exactly like that.

5 个评论
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KALYAN ACHARJYA 2019-12-18

One way Here

https://in.mathworks.com/help/images/ref/adapthisteq.html

Maryam Al-Muhaini 2019-12-18

I don't get it. I'm a beginner at using matlab

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Answer 2

Image Analyst 2019-12-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/497265-color-enhancement-using-histogram#answer_407169

在 MATLAB Online 中打开

Try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clearvars;
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;
%=======================================================================================
% Have user browse for a file, from a specified "starting folder."
% For convenience in browsing, set a starting folder from which to browse.
% startingFolder = pwd;  % or 'C:\wherever';
% if ~exist(startingFolder, 'dir')
% 	% If that folder doesn't exist, just start in the current folder.
% 	startingFolder = pwd;
% end
% % Get the name of the file that the user wants to use.
% defaultFileName = fullfile(startingFolder, 'n*.*');
% [baseFileName, folder] = uigetfile(defaultFileName, 'Select a file');
% if baseFileName == 0
% 	% User clicked the Cancel button.
% 	return;
% end
folder = 'C:\Program Files\MATLAB\R2019b\toolbox\images\imdata';
baseFileName = 'pears.png';
baseFileName = 'toysflash.png';
fullFileName = fullfile(folder, baseFileName);
rgbImage = imread(fullFileName);
% Get the dimensions of the image.
[rows1, columns1, numberOfColorChannels1] = size(rgbImage)
% Display the original image.
subplot(2, 2, 1);
imshow(rgbImage, []);
axis('on', 'image');
caption = sprintf('Original Color Image\n"%s"', baseFileName);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0.05 1 0.95]);
% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by Image Analyst', 'NumberTitle', 'Off')
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
% Get histograms
histR = imhist(redChannel);
histG = imhist(greenChannel);
histB = imhist(blueChannel);
% Get the mean
histMean = (histR + histG + histB) / 3;
theCDF = cumsum(histMean);
% Normalize 0 - 1
theCDF = rescale(theCDF, 0, 255);
subplot(2, 2, 2);
plot(theCDF, 'b-', 'LineWidth', 2);
grid on;
xlabel('Input Gray Level', 'FontSize', fontSize);
ylabel('Output Gray Level', 'FontSize', fontSize);
title('The CDF', 'FontSize', fontSize, 'Interpreter', 'None');
% theCDF is the intensity mapping
lut = uint8(theCDF);
% Expand the channels
newR = intlut(redChannel, lut);
newG = intlut(greenChannel, lut);
newB = intlut(blueChannel, lut);
% Combine them all into a new RGB image.
rgbImage2 = cat(3, newR, newG, newB);
% Display the image.
subplot(2, 2, 3);
imshow(rgbImage2, []);
axis('on', 'image');
title('Final Image', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.