[Gdal-dev] adjust colors

[Gillian Walter]

You might be able to use gdal_translate with the "-scale" option instead,
if you knew in advance how much you wanted to rescale by (eg. if you opened
the image in OpenEV, played with the scale min/max settings until you liked
them, and used those).  You might have to split the bands out first though,
since I don't know if you can specify separate scaling ranges for each
band.  You could use vrt as an intermediate format to save space:

eg.
gdal_translate -of VRT -b 1 -scale 100 200 test.tif b1.vrt
gdal_translate -of VRT -b 2 -scale 50 200 test.tif b2.vrt
gdal_translate -of VRT -b 3 -scale 10 200 test.tif b3.vrt
<edit b1.vrt to contain the VRTRasterBand sections of b2.vrt and b3.vrt as
well>
gdal_translate -of GTiff b1.vrt output.tif

Note: the above would translate the a source value of 100 to a destination
value of 0 and 200 to 255 for the first band, a source value of 50 to a
destination value of 0 for the second band, etc.

- Gillian

Ethan Alpert wrote:

> You may want to look at Imagemagick. The one caveat is you'll need to
> save your projection information and use gdal_translate/gdalwarp to
> reapply the projection information. Another caveat is I've found that
> NODATA values are can cause some of imagemagicks functionality to behave
> abnormally.
>
> -e
>
> -----Original Message-----
> From: gdal-dev-bounces at xserve.flids.com
> [mailto:gdal-dev-bounces at xserve.flids.com] On Behalf Of joerg p
> Sent: Sunday, October 10, 2004 9:44 AM
> To: gdal-dev at remotesensing.org
> Subject: [Gdal-dev] adjust colors
>
> hello,
>
> is there actually a tool to adjust the colors of a geotiff? I have
> several 1.2 GB geotiffs and would like to have the red values more blue
> and the green not so strong...
>
> I could open them with Photoshop, but this will take ages...
>
> Thanks
> Joerg
>
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