2531 Rate this article: No rating What is the equation for ENVI's Photographic Stretch routine? This Help Article discusses the equation for ENVI's photographic stretch routine since there are no references for this routine currently. This example covers the red band, but it is exactly the same for green and blue: out_red = in_red/(1+in_red*lambda) where lambda=(max-(2*mean)) / (max*mean) where max and mean are combined for all bands. If the "lambda" factor is less than 0, then the input is the same as the output. Review on 12/31/2013 MM Please login or register to post comments. What is the difference between a 'Pixel-based' and 'Map-based' Arbitrary projections? How can I import my GPS Points into ENVI Classic?