How can i plot a color bar for an RGB image ?

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sam  CP
sam CP on 24 Jun 2018
Answered: Walter Roberson on 25 Jun 2018
RGB = imread('saturn.png');
I = rgb2gray(RGB);
h = [1 2 1; 0 0 0; -1 -2 -1];
I2 = filter2(h,I);
imshow(I2,'DisplayRange',[]), colorbar
I have found the above codes for grayscale image.

Answers (2)

KSSV
KSSV on 25 Jun 2018
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Walter Roberson
Walter Roberson on 25 Jun 2018
RGB images do not have colorbars. colorbar relates a linear (or log) value to the color the value is mapped to, but RGB images express color directly; there is no linear (or log) value being mapped to a color.
We could create a bar chart relating each RGB color to the number of times that color occurs, but your image has over 150000 RGB colors so you would need like 100 displays end to end even if the bars were only one pixel wide.

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