I'd like to choose random samples from multispectral image according to each Land Cover image. The multiband image has 70 bands representing land surface temperature data from MODIS. Land cover image has 9 classes. I need 50 sample (pixel) values of each land cover type which extracted from each band of multispectral image. How can I choose these random samples in ARCGIS, ERDAS and EVI? ENVI can be used to choose random samples on multiband image as ROI. But statistic output of ROI gave me the descriptive statistics of mean of all sample. What I want is the mean value of each separate samples of each land cover types in each bands.

Thanks in advance