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In my class I often need to work with color map images. I would show the image and try to make inferences/observations about different subjects. Often times I need to actually quantify some aspects, but it is always very approximate and somehow vague because the images are provided "as is" and I do not necessarily know their content a priori.

Let's imagine I'm working with two images (*). I would love to tell my computer to "learn" the color scale bar so I can click at any point in the map to get the value of altitude at that point? Image 1 is a discrete color scale bar, while Image 2 has a continuous color mapping. I included both examples because maybe there are differences in the approach of how to do this.

So, is there a software/way to do this? Preferably open source. I tried ImageJ and couldn't come up with a decent solution.

(*) Image 1: https://upload.wikimedia.org/wikipedia/commons/2/24/AYool_topography_15min.png

(*) Image 2: http://topocreator.com/ned-jpg/city_a/600/co.jpg

(*) I do not own any of these images, just examples I found online to illustrate my point.

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closed as off-topic by A_A, MBaz, lennon310, Matt L., jojek Jan 29 '18 at 23:16

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about signal processing within the scope defined in the help center." – A_A, MBaz, lennon310, Matt L., jojek
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ I am afraid that this question is off-topic for DSP.SE. The GIS.SE might have something more to say on the subject though. Having said that, if this were a height map on some platform like MATLAB for example, I would bring both height maps to the same scale (by linearly mapping one to the extents of the other) and then plot them on the same colormap. In this way, the correspondence of colours would match exactly. $\endgroup$ – A_A Jan 23 '18 at 16:43
  • $\begingroup$ Isn't this an image processing question? $\endgroup$ – endolith Jan 23 '18 at 22:35
  • $\begingroup$ So the colorbars are part of the image file already? $\endgroup$ – AnonSubmitter85 Jan 24 '18 at 5:17
  • $\begingroup$ DSP.SE: "Q&A for practitioners of the art and science of signal, image and video processing". Thus I thought it was appropriate to ask here, but sorry if it's not. $\endgroup$ – terauser Jan 24 '18 at 12:36
  • $\begingroup$ Yes, as you can see in the links, the color bars are part of the image file. I usually get the images from colleagues or just from internet. $\endgroup$ – terauser Jan 24 '18 at 12:37

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