Pick the colormap from a colorbar in an image.

When you want to compare your results with someone else's, it can be hard to reproduce a map or a plot with a colormap that you don't have in your setup. This tool allows you to create a colormap that matches that of any figure. You just have to accurately select where the colorbar is on the image/figure.

Here's an example of extracting the colormap from an image with some of matplotlib's colormaps:

(Note I'm not very precise in my selection, surely you can do better!)

To check if you got it right, a colorbar with your newly created colormap is shown on the right.

Requires the Image Processing Toolbox!

1. Find an image with a colorbar you want (e.g., take a screenshot)

2. Call cmap = cmap_picker(image_path) This will open a figure window with your image displayed in it. (Don't forget to edit image_path to be your image's path!)

3. And draw a rectancgle with your mouse (click-and-drag)! A colormap will be built by averaging over the colorbar's "width" (depending on the orientation of your rectangle). And a colorbar will be added to the figure to show you the colormap you just created.

Try this command and select whichever colorbar you want!

cmap = cmap_picker('https://matplotlib.org/stable/_images/sphx_glr_colormaps_001_2_0x.png');

You can then save the variable cmap or use it once, as you would anyother colormap!