I am interested in generating a color bar from a colored image.

I have attached the image. What I would like is a color bar that displays all the colors on the figure. The figure represents elevation data.

Answer 1

[Image Analyst]

If you don't know the colormap, then you will need the indexed image, not the RGB one.

[Walter Roberson]

Even if you had the colormap (perhaps extracted from a pseudocolor image), that would not tell you the order of colors, or which color correspond to what height.

[Image Analyst]

Here is a scatterplot of all the colors in your image. They cannot be plotted with a colorbar.

[Abdul Wahab]

How do I make a color bar of the colors displayed on the image to thre right?

[Image Analyst]

You can't but you mgiht be able to get roughly close if you have a gray scale image, and you map the gray scaled from 0-255 basically along the centroid of that colored snake-like gamut. Sorry, I don't have any code to automatically do that. Can you ask the image originator for the original gray scale image and the color map they used?