[GRASS-dev] Re: i.rgb.his/i.his.rgb and 16bit images

Hamish hamish_b at yahoo.com
Sun Oct 4 22:58:56 EDT 2009

Georg Kaspar wrote:
> > do you know of any free-for-download QuickBird data for testing it
> > with?
> http://glcf.umiacs.umd.edu/data/quickbird/

I have tried to load some of that and found a few things.
Now documented in the GRASS wiki:

With that I can get a RGB image that looks mostly-pseudo-true-color.

* red and blue bands are imported backwards and must be renamed.

This post claims it is a data provider problem, but I quietly suspect
that it may be a GDAL problem after all. (?)

* data is excessively dark and green band is higher gain than rest.

You can use i.landsat.rgb to rebalance the RGB, but gains/saturation is
still a bit off. I'm not sure if you are supposed to use the Panchromatic
channel to set the brightness, or... ? ISTR that some commercial provider
intentionally degraded Freebie offerings, not sure if that is the case
here or there is some calibration issue that we are not aware of.

Was your desire to use i.rgb2his in order to fix the brightness issue, or
was it for some analysis purpose?



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