I have a georeferenced png file of a colorfilled contour map. I need to get the contours off of it. Digitizing the areas of gradient colorfill is proving very problematic because gradient. Is there a way to do something with this image to make the various colors into their values and then generate contours from it, rather than hand-tracing around the color blobs?
I'm not even sure I'm asking the question very well, as I normally work with vector data, but would appreciate any help or insight.
I've attached the original image which might clear up my questions. The contour lines on this map I do not need, what I am trying to get are contours based on the colors.