MATLAB Answers

how to show lab space image

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xiao
xiao on 2 May 2018
Commented: Arthur Fernandes on 19 Nov 2018
lab color space is (0-100),(-128-127),(-128-127), given an image under lab color space, how to show it suitably (imshow is not appropriate)?

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Accepted Answer

Ameer Hamza
Ameer Hamza on 2 May 2018
What about conversion to RGB before displaying.
imshow(lab2rgb(image));

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xiao
xiao on 2 May 2018
then does this have any difference with imshow(imread(image)) directly? Is this just the way what lab space look like?

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More Answers (1)

Image Analyst
Image Analyst on 2 May 2018
You can look at each channel one at a time
subplot(3, 1, 1);
imshow(labImage(:, :, 1), []);
title('L Image', 'FontSize', 20);
subplot(3, 1, 2);
imshow(labImage(:, :, 2), []);
title('A Image', 'FontSize', 20);
subplot(3, 1, 3);
imshow(labImage(:, :, 3), []);
title('B Image', 'FontSize', 20);

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Arthur Fernandes
Arthur Fernandes on 16 Nov 2018
That is good but there is anyway to save each subplot to file? That is not using the the save menu option? I'm asking because using any of the following code will write an image that is not using the same mapping in gray scale:
imwrite(labImage(:, :, 3),'imgfile.png');
imwrite(labImage(:, :, 3),gray(100),'imgfile.png');
imwrite(labImage(:, :, 3),gray(256),'imgfile.png');
Nor the following:
imshow(labImage(:, :, 3), []);
cmap = colormap;
imwrite(labImage(:, :, 3),cmap, 'imgfile.png');
Image Analyst
Image Analyst on 16 Nov 2018
If you want a grayscale rendering of the image, not the actual values, you can convert to uint8 and then use a standard format like PNG:
uint8Image = uint8(255 * mat2gray(labImage(:, :, 1)));
imwrite(uint8Image, 'L Channel.PNG');
uint8Image = uint8(255 * mat2gray(labImage(:, :, 2)));
imwrite(uint8Image, 'A Channel.PNG');
uint8Image = uint8(255 * mat2gray(labImage(:, :, 3)));
imwrite(uint8Image, 'B Channel.PNG');
Arthur Fernandes
Arthur Fernandes on 19 Nov 2018
I didn't know about that mat2gray function, I was wandering if Matlab had someting more direct. But still better than using my on code. Thank you!

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