MATLAB: RGB values in a YUV colorspace image

image processingimshow

I have an image in YUV colorspace and when i preview it using imshow() function,the image shows RGB values at each pixel but when i type img_name(x,y,:) in the workspace,it shows some other values. So how do i get those RGB values which are shown in the figure using the imshow() function in the workspace or use them for further processing.

Best Answer

How did you get that image in that color space? Was it from a camera?

Also, the value is different from workspace (variable editor) to what you type in because you typed in the wrong thing. You typed in img_name(x,y,:) instead of img_name(y, x, :). Remember, with matrices the ROW is the first index, not the column.

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MATLAB: Converting Colors to Other Colors

Load image

RGB = imread('image.png');

Image is stored as a nxmx3 matrix, where the 3 layers are red, green and blue pixel intensity and nxm is the resolution. Find pure red colors by finding the indices with strong red channels (1st layer close to 255) and weak green/blue channels (2nd and 3rd channels clsoe to zero).

mask = RGB(:,:,1)>230 & RGB(:,:,2)<1 & RGB(:,:,3)<1;

then you can use this mask to change the colors of your image

RGB(repmat(~mask,1,1,3)) = 0;
RGB(repmat(mask,1,1,3)) = 255;

imshow(RGB)

MATLAB: Index exceeds matrix dimensions.I am working on hand gesture recognition.

It seems your image is a gray image..it doesn't have R, G and B channels. See to it that, you use a color image i.3 3D matrix as input. Try this function:

function region=skinDetect2func(img)
img = imread('peppers.png') ;
[m,n,p] = size(img) ;
if p ~=3
    error('Please input a color image')
end
imshow(img);
sz=size(img);
r=1;g=2;b=3;y=1;u=2;v=3;
yuv=img;
region=yuv;
yuv(:,:,y) = (img(:,:,r)+2.*img(:,:,g)+img(:,:,b))/4;
yuv(:,:,u) = img(:,:,r)-img(:,:,g);
yuv(:,:,v)=img(:,:,b)-img(:,:,g);
region = (yuv(:,:,u)>20 & yuv(:,:,v)<74) .* 255;

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MATLAB: Converting Colors to Other Colors

MATLAB: Index exceeds matrix dimensions.I am working on hand gesture recognition.

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