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pythonrgbdata-conversion

How to build elevation scale from an RGB map?

I need to build a correspondence map between colors and altitudes. The elevation file has blue color for sea and green/yellow/brown colors for elevation. The advice says:

Find the pixel of the Mont Blanc (4810 m).

Text

I'm working with Python. I don't know how to solve this. I converted the map into a NumPy array of shape (2860,4490,3) with RGB values and want to transform into (2860,4490) with elevation value in meter.

Solution

  • Convert the RGB image to HSV colorspace to see with 'Hue' landmass can be linearly mapped. Treat water separately.

    • Read slide 13 here.
    • Last answer here illustrates this.
    • You could use scikit image for processing:
    from skimage.color import rgb2hsv

rgb_img = np.array(your_image)
hsv_img = rgb2hsv(rgb_img)
hue_img = hsv_img[:, :, 0]

    Taken from here.