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Convert a 32 bits tiff to a 8bits colored tiff

Question asked by robinne on Feb 16, 2017

Hi guys,

 

I have a 32bits (values 0-293) 1km-resolution raster showing the distribution of a species across North America.

For display purpose, I need to rescale this file to an integer 0-255 scale, apply a colour ramp to it, and get a final tiff image that one can open in an image viewer and see the same thing.

I thought it would be quite easy...it's not

I used the copy raster to convert my original file to an unsigned 8bits, so the result is scaled on 0-255. Then I added a colormap, and in the display, it looks fine. But then, when I export my data, the null value (the ocean) has been coded to 0 and assigned with the corresponding value from the colormap.

It seems that a 16bits format would be more appropriate in order to store the null value, but then, do I have to rescale my raster to 0-255 before I copy it?

I tried the "export map", but it's not convenient, as I can't automate it, and I have to set the resolution very high in order to keep a resolution similar to 1k.

Any idea how I can deal with this?

Thanks

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