[GRASSLIST:1164] problems

[Andrzej Wroblewski]

Dear grass users

I have cuple question:

1. It's obvieus that picture made from satelite in mountain terrain have different illumination of slopes. That cause different pixel values in sattelite image. Is in grass any function elimination that problem?

2. Haw to streach contrast in grass?

3. r.mapcalc
      > out=(ch3/ch1)*90
when complete writes:
min values 0, max values 0
(ch1 and ch3 are my picture)

Why? what's wrong?

I will appreciate your help

Best regards,

Andrzej Wroblewski