How can i get a RGB values from a picture?

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caner kaya 2017-10-10

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评论： DGM 2022-12-2

Hi,

My goal is to get the RGB values of the image taken with the webcam and I need the matlab code to accomplish this purpose. I am a new matlab user, please help me.

Best regards.

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Walter Roberson 2017-10-10

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See https://www.mathworks.com/help/supportpkg/usbwebcams/ug/acquire-images-from-webcams.html on how to work with webcams.

Once you have done the snapshot(), then just index into the resulting array to get the RGB values. For example,

img(183, 17, :)

would extract the R, G, and B components (in that order) of row 183 column 17 of the image.

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Image Analyst 2021-1-27

编辑：Image Analyst 2021-1-27

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What do you want represented along each axis? LIke R along , G along Y and B along Z?

Like this:

rgbImage = double(imread('peppers.png'));
[r, g, b] = imsplit(rgbImage);
xyz = [r(:), g(:), b(:)];
ptCloud = pointCloud(xyz);
pcshow(ptCloud)

Looks pretty much like what you get from colorcloud():

Walter Roberson 2021-1-28

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Your color data can be either 2D or 3D

numFaces = 600;

[x,y,z] = sphere(numFaces);

xyz2d = [x(:), y(:), z(:)];

xyz3d = cat(3,x,y,z);

img = imresize(imread('flamingos.jpg'), [numFaces+1, numFaces+1]);

color_matrix_2d = reshape(img, [], 3);

color_matrix_3d = img;

pcshow(xyz2d, color_matrix_2d); title('data arranged as 2d')

pcshow(xyz3d, color_matrix_3d); title('data arranged as 3d')

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Chad Greene 2017-10-10

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Hi Caner,

The imread function will read any image and give you the RGB values like this:

A = imread('myimage.jpg');

Then the red layer is the first slice of A, blue is the second slice, and green is the third:

R = A(:,:,1); 
G = A(:,:,2); 
B = A(:,:,3);

If you need the RGB values of a specific pixel, say, row 22, column 50, it would be:

[R(22,50) G(22,50) B(22,50)]

If you're not sure what the row and column numbers are of the pixel you want, display the image with the image function, then use ginput to click around and get the coordinates you want:

image(A) 
[col,row] = ginput

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Shri.s 2022-12-2

This solution does not shows the RGB values?

DGM 2022-12-2

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This does show the RGB values at a specific pixel.

% an image
A = imread('peppers.png');
% split the channels
R = A(:,:,1); 
G = A(:,:,2); 
B = A(:,:,3);
% address each channel to find the color at (22,50)
[R(22,50) G(22,50) B(22,50)]
ans = 1×3
   61   35   65
% of course, this is the same as
permute(A(22,50,:),[1 3 2])
ans = 1×3
   61   35   65

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Image Analyst 2017-10-11

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To build on what the others said, you should look at impixelinfo() which is a function that puts a status bar on your figure that gives you the (x,y) location and RGB values as you mouse over the displayed image.

There is also a function called impixel() that gives you the RGB value but I never use it.

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caner kaya 2017-10-11

I need to find R G B values between 0 and 255 for a picture for example if the picture pure red then R=255, G=0, B=0, I should get these values

caner kaya 2017-10-11

编辑：caner kaya 2017-10-11

I also have a problem, the RGB values I get are not affected by the environment. I mean I should get the * same* values even if I'm in the dark or the bright environment with the using the webcam

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Bryan Benedict Ordas 2019-12-19

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Hello Guys!

I am also in need of help on getting the RGB values in a multiple images. I was able to know also that you can pick a certain coordinates using your mouse to select the pixel you wanted to obtain the RGB Values. What if I wanted to use this function for multiple pictures? is there a way on looping this activity? (selecting pixels and getting the RGB Values of Multiple Pictures).

My purpose was to gather data of a certain object for neural networks.

Thanks!!!