Personalized RGB Masked Image

Question

Allinone 2021-10-22

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移动：DGM 2023-3-4

Hi everyone! I'm very new in MatLab Programming.

I have a RGB image and I want that certains color pixels are white, certain pixels are black and the others grey. I used the Threshold Apps (with binary mask), but I have only black or white pixels.

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Answer 1

Image Analyst 2021-10-22

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https://ww2.mathworks.cn/matlabcentral/answers/1569723-personalized-rgb-masked-image#answer_814363

I'm not sure what you are asking. So what does your original image look like? What do you mean that you want white, black, and gray pixels?

If you use the Color Thresholder app (on the Apps tab of the Tool Ribbon) you can find thresholds to segment out a certain color, like red for example. This will create a mask where it's true/1/white where there are red pixels and false/0/black where the pixels are not red.

Attach your image and explain better if you need more help.

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Image Analyst 2021-10-25

移动：DGM 2023-3-4

在 MATLAB Online 中打开

Attached is a full demo:

% Demo by Image Analyst.
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;
fprintf('Beginning to run %s.m ...\n', mfilename);
%-----------------------------------------------------------------------------------------------------------------------------------
% Read in image.
folder = [];
baseFileName = 'peppers.png';
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
    % The file doesn't exist -- didn't find it there in that folder.
    % Check the entire search path (other folders) for the file by stripping off the folder.
    fullFileNameOnSearchPath = baseFileName; % No path this time.
    if ~exist(fullFileNameOnSearchPath, 'file')
        % Still didn't find it.  Alert user.
        errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
        uiwait(warndlg(errorMessage));
        return;
    end
end
rgbImage = imread(fullFileName);
[rows, columns, numberOfColorChannels] = size(rgbImage)
% Display the image.
subplot(2, 3, 1);
imshow(rgbImage, []);
axis('on', 'image');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
caption = sprintf('Original RGB Image : "%s"\n%d rows by %d columns', baseFileName, rows, columns);
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.
hFig1 = gcf;
hFig1.Units = 'Normalized';
hFig1.WindowState = 'maximized';
% 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.
hFig1.Name = 'Demo by Image Analyst';
%-----------------------------------------------------------------------------------------------------------------------------------
% Get the red mask
[redMask, maskedRGBImageR] = createRedMask(rgbImage);
% Display the image.
subplot(2, 3, 2);
imshow(redMask, []);
axis('on', 'image');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
title('Red Mask', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
% Display the image.
subplot(2, 3, 3);
imshow(maskedRGBImageR, []);
axis('on', 'image');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
title('Red Mask', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
%-----------------------------------------------------------------------------------------------------------------------------------
% Get the green mask
[greenMask, maskedRGBImageG] = createGreenMask(rgbImage);
% Display the image.
subplot(2, 3, 5);
imshow(greenMask);
axis('on', 'image');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
title('Green Mask', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
% Display the image.
subplot(2, 3, 6);
imshow(maskedRGBImageG, []);
axis('on', 'image');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
title('Green MaskedImage', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
%-----------------------------------------------------------------------------------------------------------------------------------
% Create gray mask.  It's all gray except where it's red or green.
grayMask = true(size(redMask)) & ~redMask & ~greenMask;
% Make final image by adding red mask image to gray mask image.
% Green is zero so no need to add it in.
output = uint8(255 * redMask + 128 * grayMask);
% Display the image.
subplot(2, 3, 4);
imshow(output);
axis('on', 'image');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
title('Gray Image', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
msgbox('Done!');
%======================================================================================================================
function [BW,maskedRGBImage] = createRedMask(RGB)
%createMask  Threshold RGB image using auto-generated code from colorThresholder app.
%  [BW,MASKEDRGBIMAGE] = createMask(RGB) thresholds image RGB using
%  auto-generated code from the colorThresholder app. The colorspace and
%  range for each channel of the colorspace were set within the app. The
%  segmentation mask is returned in BW, and a composite of the mask and
%  original RGB images is returned in maskedRGBImage.
% Auto-generated by colorThresholder app on 25-Oct-2021
%------------------------------------------------------
% Convert RGB image to chosen color space
I = rgb2hsv(RGB);
% Define thresholds for channel 1 based on histogram settings
channel1Min = 0.934;
channel1Max = 0.043;
% Define thresholds for channel 2 based on histogram settings
channel2Min = 0.318;
channel2Max = 1.000;
% Define thresholds for channel 3 based on histogram settings
channel3Min = 0.000;
channel3Max = 1.000;
% Create mask based on chosen histogram thresholds
sliderBW = ( (I(:,:,1) >= channel1Min) | (I(:,:,1) <= channel1Max) ) & ...
    (I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ...
    (I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max);
BW = sliderBW;
% Initialize output masked image based on input image.
maskedRGBImage = RGB;
% Set background pixels where BW is false to zero.
maskedRGBImage(repmat(~BW,[1 1 3])) = 0;
end
%======================================================================================================================
function [BW,maskedRGBImage] = createGreenMask(RGB)
%createMask  Threshold RGB image using auto-generated code from colorThresholder app.
%  [BW,MASKEDRGBIMAGE] = createMask(RGB) thresholds image RGB using
%  auto-generated code from the colorThresholder app. The colorspace and
%  range for each channel of the colorspace were set within the app. The
%  segmentation mask is returned in BW, and a composite of the mask and
%  original RGB images is returned in maskedRGBImage.
% Auto-generated by colorThresholder app on 25-Oct-2021
%------------------------------------------------------
% Convert RGB image to chosen color space
I = rgb2hsv(RGB);
% Define thresholds for channel 1 based on histogram settings
channel1Min = 0.145;
channel1Max = 0.491;
% Define thresholds for channel 2 based on histogram settings
channel2Min = 0.333;
channel2Max = 1.000;
% Define thresholds for channel 3 based on histogram settings
channel3Min = 0.000;
channel3Max = 0.969;
% Create mask based on chosen histogram thresholds
sliderBW = (I(:,:,1) >= channel1Min ) & (I(:,:,1) <= channel1Max) & ...
    (I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ...
    (I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max);
BW = sliderBW;
% Initialize output masked image based on input image.
maskedRGBImage = RGB;
% Set background pixels where BW is false to zero.
maskedRGBImage(repmat(~BW,[1 1 3])) = 0;
end

Allinone 2021-10-28

移动：DGM 2023-3-4

Ok, thank you! Now it works. I tried with others colors, but I haven't gray level. Why do?

This is my code ( I want Yellow objects become white, green objects become black, and the rest greysh):

rgbImage = imread('....');

[rows, columns, numberOfColorChannels] = size(rgbImage);

[greenMask, maskedRGBImageG] = createGreenMask(rgbImage);

[yellowMask, maskedRGBImageY] = createYellowMask(rgbImage);

grayMask6 = true(size(greenMask)) & ~greenMask & ~yellowMask;

output = uint8(255 * yellowMask + 70 * grayMask6);

%subplot(5, 7, 13);

imshow(output);

title('G-Y');

%GREEN

function [BW,maskedRGBImage] = createGreenMask(RGB)

I = rgb2hsv(RGB);

channel1Min = 0.145;

channel1Max = 0.491;

channel2Min = 0.333;

channel2Max = 1.000;

channel3Min = 0.000;

channel3Max = 0.969;

sliderBW = ((I(:,:,1) >= channel1Min) & (I(:,:,1) <= channel1Max)) & ...

(I(:,:,2) >= channel2Min) & (I(:,:,2) <= channel2Max) & ...

(I(:,:,3) >= channel3Min) & (I(:,:,3) <= channel3Max);

BW = sliderBW;

maskedRGBImage = RGB;

maskedRGBImage(repmat(~BW,[1 1 3])) = 0;

end

function [BW,maskedRGBImage] = createYellowMask(RGB)

I = rgb2hsv(RGB);

channel1Min = 0.177;

channel1Max = 0.108;

channel2Min = 0.000;

channel2Max = 1.000;

channel3Min = 0.000;

channel3Max = 1.000;

sliderBW = ((I(:,:,1) >= channel1Min) & (I(:,:,1) <= channel1Max)) & ...

(I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ...

(I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max);

BW = sliderBW;

maskedRGBImage = RGB;

maskedRGBImage(repmat(~BW,[1 1 3])) = 0;

imshow(maskedRGBImage);

end

Allinone 2021-10-28

移动：DGM 2023-3-4

This is your example, that I modiified and it works perfectly:

rgbImage = imread('...');

[rows, columns, numberOfColorChannels] = size(rgbImage);

[greenMask, maskedRGBImageG] = createGreenMask(rgbImage);

[redMask, maskedRGBImageR] = createRedMask(rgbImage);

grayMask4 = true(size(greenMask)) & ~greenMask & ~redMask;

output = uint8(255 * redMask + 70 * grayMask4);

%subplot(5, 7, 11);

imshow(output);

title('G-R');

================================================================================

%GREEN

function [BW,maskedRGBImage] = createGreenMask(RGB)

I = rgb2hsv(RGB);

channel1Min = 0.145;

channel1Max = 0.491;

channel2Min = 0.333;

channel2Max = 1.000;

channel3Min = 0.000;

channel3Max = 0.969;

sliderBW = ((I(:,:,1) >= channel1Min) & (I(:,:,1) <= channel1Max)) & ...

(I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ...

(I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max);

BW = sliderBW;

maskedRGBImage = RGB;

maskedRGBImage(repmat(~BW,[1 1 3])) = 0;

================================================================================

%RED

function [BW,maskedRGBImage] = createRedMask(RGB)

I = rgb2hsv(RGB);

channel1Min = 0.934;

channel1Max = 0.043;

channel2Min = 0.318;

channel2Max = 1.000;

channel3Min = 0.000;

channel3Max = 1.000;

sliderBW = (I(:,:,1) >= channel1Min ) | (I(:,:,1) <= channel1Max) & ...

(I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ...

(I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max);

BW = sliderBW;

maskedRGBImage = RGB;

maskedRGBImage(repmat(~BW,[1 1 3])) = 0;

end

Image Analyst 2021-10-29

移动：DGM 2023-3-4

Those images do not have any green, yellow, or brown in them. Again, "Attach the image that has all these colors that you're working with." How can we fix your code if you won't give us the input image?

Allinone 2021-10-29

移动：DGM 2023-3-4

assortimento-fev_mobile.jpeg

It's the same image I attached before. I attached it again.

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Answer 2

Image Analyst 2021-10-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1569723-personalized-rgb-masked-image#answer_819623

Doing the same thing for yellow and brown is easy and straightforward.

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Image Analyst 2021-11-3

Copy that code multiple times with appropriate changes, or put in in a loop.

Allinone 2021-11-3

I have created a function for each pair of colors. I would like to call these functions in the main script and see all the outputs, but I don't know how do i do. Sorry..I'm very new in MatLab..

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Answer 3

Image Analyst 2021-10-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1569723-personalized-rgb-masked-image#answer_819628

Doing the same thing for yellow and green is easy and straightforward.

See my other answers for different color pairs.

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Allinone 2021-10-29

Ok, thank you so much! I wrote the same code, but with different values, so I didn't have the gray levels..

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Answer 4

Image Analyst 2021-10-29

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1569723-personalized-rgb-masked-image#answer_819633

See my discriminant analysis color segmentation demo.

Also check out my delta E demo, attached.

I've posted several new answers this session so be sure to see them all.

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Allinone 2021-10-29

编辑：Allinone 2021-10-29

Your delta E works with all colors?

Could I detect pairs colors with your delta E, or threshold is better?

Image Analyst 2021-10-29

The delta E demo identifies all pixels that are within a certain color distance of the average color that you outlined. It finds the delta E of all pixels in the image to the average color, and then thresholds it at the delta E you specify to find colors (anywhere in the image) that are close to what you drew. For example here I drew over the red pepper and it found all red pixels that are within a delta E of 21.9 from the average red in the region I drew.