Greetings, I am currently working on comparisons between QUAC and a new atmospheric compensation algorithm we've developed, and I would like to know a bit more about the ENVI implementation of the QUAC algorithm. In particular: How many endmembers are used in estimating the spectral standard deviation? Are the endmembers filtered (e.g., by NDVI) using the method described in Bernstein et al 2006 [1]? Are all pixels considered when computing the baseline spectrum? If all pixels are used, is any filtering performed within the QUAC function to eliminate outliers, saturated pixels, or sharp spectral features? Thanks in advance for the assistance! [1] L. S. Bernstein, S. M. Adler-Golden, R. L. Sundberg, and A. J. Ratkowski, “Improved Reflectance Retrieval From Hyper- and Multispectral Imagery Without Prior Scene or Sensor Information,” Remote Sensing, vol. 6362, pp. 63622P–63622P–8, Sep. 2006.