How to display R, G, B colours of an individual pixel in an image?

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Himawari Tanaka 2022-3-3

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评论： Image Analyst 2022-3-3

Hi everyone

I want to display the exact R, G, B colors for all pixels instead of only getting their R, G, B values where three colors are still blended per pixel. To clarify my question, I have obtained R, G, B values for all single pixels of my image using impixelregionpanel function, but I wish to display each pixel as 3 individual RGB color channels based on their values in an image, instead of having blended final color as the result. I attached the picture below as an example to clarify my point.

I wonder if there is a way to do this in MATLAB?

Thank you very much for your help.

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Answer 1

Image Analyst 2022-3-3

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在 MATLAB Online 中打开

If you want to make your own little image and display it you could do something like

rgbImage = imread('peppers.png');

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

% Get the RGB colors at some location in the image.

pixelColors = uint8(impixel(rgbImage, 20, 50))

pixelColors = 1×3

63 34 68

smallImage = pixelColors(1) * ones(300, 300, 'uint8');

smallImage(:, :, 2) = pixelColors(2); % Assign green.

smallImage(:, :, 3) = pixelColors(3); % Assign blue.

imshow(smallImage);

% Make lines across image.

smallRows = size(smallImage, 1);

yline(round(smallRows/3), 'Color', 'y', 'LineWidth', 2);

yline(round(2*smallRows/3), 'Color', 'y', 'LineWidth', 2);

% Place texts

xt = size(smallImage, 2) / 2;

% First the red value.

yt = smallRows/6;

str = sprintf('R = %d', pixelColors(1));

text(xt, yt, str, 'Color', 'y', 'FontSize', 20, 'FontWeight','bold','VerticalAlignment','middle', 'HorizontalAlignment','center');

% Next the green value.

yt = 3 * smallRows/6;

str = sprintf('G = %d', pixelColors(2));

text(xt, yt, str, 'Color', 'y', 'FontSize', 20, 'FontWeight','bold','VerticalAlignment','middle', 'HorizontalAlignment','center');

% Next the blue value.

yt = 5 * smallRows/6;

str = sprintf('B = %d', pixelColors(3));

text(xt, yt, str, 'Color', 'y', 'FontSize', 20, 'FontWeight','bold','VerticalAlignment','middle', 'HorizontalAlignment','center');

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Himawari Tanaka 2022-3-3

Unfortunately my task was to somehow make all the pixels of an image look like this. The intensity and brightness of each subpixel depends on their values of each pixel.

Thank a lot for your code. I think I will have to somehow modify the code as DGM said. I have been trying to separate RGB channel and display all pixels of the original image like above. So far, getting individual R, G, B channel of an image and their values are the best that I could get.

Image Analyst 2022-3-3

I don't know what you want, like how many rows and how many columns, whether you want text labels over the unifrmly-colored blocks or not, and the direction of the R, G, and B blocks. Presumably you do, so good luck.

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Answer 2

KSSV 2022-3-3

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MAke/ create the required coordinates/ locations where you want to put text and the use patch, text.

Read about patch and text.

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Himawari Tanaka 2022-3-3

Can you show me some code examples of how patch() and text() could be used in my case? I have been reading about those functions, but I don't understand much how they related to my topic. It would be very helpful for me, thank you a lot.

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Answer 3

Simon Chan 2022-3-3

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Use function imsplit

[R,G,B] = imsplit(I)

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Himawari Tanaka 2022-3-3

I have used the imsplit() function in my code, but in the end, all pixels only represent 1 colour of either R, G or B. For example, here is my final result of the B channel of a pixel after using imsplit. I expect the R and G to be black or white, since they are 0, but they still represent as B colour with value 80.

Do you know how can I code this differently? Thank you a lot in advance.

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Answer 4

Image Analyst 2022-3-3

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See Steve Eddins File Exchange submission

https://www.mathworks.com/matlabcentral/fileexchange/32273-im2html-m

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DGM 2022-3-3

I'm pretty sure that if you want that, you're going to have to roll your own. You might be able to work off of im2html() or even impixelregionpanel(), but I don't know of any solution that would work without modification.

Himawari Tanaka 2022-3-3

Thanks alot for your insight. I was wondering if you know some modifications that I could apply?

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