[Qgis-user] Extract colour categories from tif file

[Nick Hopton]

NickS wrote
>  I have a very simple georeferenced tif image file - it has about 8
> different colour categories, which represent numeric ranges. How can I
> convert the colours (which are in RGB format) into a raster, or better
> still into a polygonised vector file? 

Raster -> Conversion -> RGB to PCT will convert an RGB image to a one-band
indexed (paletted) image. You should be able to polygonise this by going
Raster -> Conversion -> Polygonize.

I haven't checked but it might even be possible to polygonise the image
directly, without converting it to PCT first.

N. 




--
View this message in context: http://osgeo-org.1560.n6.nabble.com/Extract-colour-categories-from-tif-file-tp5032291p5032411.html
Sent from the Quantum GIS - User mailing list archive at Nabble.com.