[GRASSLIST:7557] color balancing in mosaic

[Feng Tan]

Hi, There,

I have problem to do color balancing for a mosaiced composited landsat TM 
images. There are 4 images, they have difference in colors. I used r.blend, 3 
of the image colorr are close now. But the 4th image have a very big 
difference in color tone with other 3, it seems r.blend does not work for it. 
Do you have a better way for this? I am running GRASS6.0 now. Please help!!

Thanks!!

Feng Tan