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Converting a map to coloured areas

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I'm looking for some help in creating an image for use as a raster in a GIS application.

I have some land use survey maps from the 1903s and I need to have a raster of the areas of different land uses (which I can later polygonise, etc.). I'm trying to avoid having to draw all the polygons out manually, so I thought there may be a way to create these rasters from the original map scans.

Attached are two files: 'Original' shows the style of the original maps, and 'Output' shows something along the lines of what I'm trying to achieve, only I need it more 'in focus' and using distinct colours only (maximum of 6, if possible, as there are 6 different classes on the original maps).

Does anyone know if this can be done in Paint.net? I have access to Photoshop if there's something I can use in that.




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Try this:


1. Open original scanned image.

2. Duplicate the layer and highlight the upper layer in the Layers Window.

3. Run Effects > Noise > Reduce Noise with settings of Radius=39(give or take) and Strength of 0.76 (again, variable).

4. Repeat Reduce Noise with the same settings using Ctrl + F.  Apply five more times.

5. Run Effects > Noise > Median with settings of Radius=10, Percentage=78.






You can lower the number of colors with Adjustments > Posterize

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After experimenting with the suggestions made above by Ego Eram Reputo, I've got pretty close to what I need now (see attachment - note, it's not the same area as the first post).

What I've done is:

  1. Upped the saturation to 125.
  2. Reduce noise (radius = 30, strength = 0.70) x2
  3. Surface blur (radius = 15, threshold = 20)
  4. Contrast +25
  5. Magic wand (tolerance = ~25%), selecting each colour (i.e., land cover type). Then, for each colour:
    1. Create a new layer
    2. Fill the selecting in this new layer with a solid colour
    3. Gaussian blur+ (radius = 2)
    4. Transparency (100% opaque)
    5. Median (radius = 5, percentile = 30)
  6. Flatten the image and remove the background.

There are some small parts that are still slightly off, so I'm still adjusting certain values here and there. All in all, though, it should be a lot quicker than manually 'repainting' the whole map (and the other 10!).


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