[Qgis-user] raster image to grid

[Matt Boyd]

Hi QGISers,
I've got an RGB image in tiff & png format, just a scan of a paper map that
represents a grid with an arbitrarily defined colour scale. Somethign like
orange red=700 to blue = 1200. There are also a number of other issues with
the image, it's a bit speckled, there are black contours etc.

I'm hunting for a way to turn the grid into something I can do work on
(this would save me having to recreate the data that the image came from)
by work I mean calculations on the numbers that the colours represent.

I don't need it super accurate but I'm struggling to work out what sort of
words I should be googling.

Does anyone have any ideas?

Thanks
Matt
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