ok, it was not well defined - i want not eliminate the clouds, i want to reduce these...
I use Atcor 2 and my images did i create from landsat data. (Landsat TM 5). -> http://glcf.umd.edu/data/landsat/
downloaded all bands(tiff) and created an image file. based on the date, i made my calibration file with bias and gain.
thats all, what i can say - no big deal