MATLAB: Is greyscale yellow and blue

image analysisimage processingMATLAB

I followed advice from this thread.

I got rid of the third dimension in the array, but now when I display grayscale picture using command:

    image(Obrazek)

I get this:

Why is supposed grayscale picture yellow-blue, instead of gray?

Best Answer

It looks like a colormap is being applied without your knowledge. I'd use imshow() instead of image. Otherwise you can set the colormap to gray(256);

colormap(handleToAxes, gray(256));

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MATLAB: Assigning color to gray image

I'd just use colormap and not mess with contours unless you know what you're doing and what you want. To pseudocolor a grayscale image an leave it as grayscale but display it as colored:

imshow(grayImage);
colormap(jet(256));
colorbar;

To convert a grayscale image into a true color RGB image and display the RGB image instead of the pseudocolored image:

rgbImage = ind2rgb(grayImage, jet(256));
imshow(rgbImage);

You don't use color bars with RGB images.

MATLAB: Imread makes 3D array from simple png

Because it's a color image. The only two colors in it are black and white, but it's still color (with 2 colors). If you want a gray scale image, simply extract one of the color channels:

obrazek = obrazek(:, :, 2); % Extract green channel.  Resulting image will be grayscale.

Best Answer

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MATLAB: Assigning color to gray image

MATLAB: Imread makes 3D array from simple png

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