John Christian

R/Rc is the ratio of the actual reflectance spectrum to the continuum spectrum (basically a straight line connected over the absorption band). ENVI has a Continuum Removal tool (see https://www.harrisgeospatial.com/docs/ContinuumRemoval.html) which looks to me like it performs this calculation for you. If you start with the M3 reflectance images (files that end in "_rfl.img") and use the Continuum Removal tool, the result should be the ratio R/Rc for each band. Then you can use the Band Math tool to put together the sums needed to calculate integrated band depth. Note: I'm not all that familiar with M3 data processing, so you might want to confirm this is the right approach with someone from the M3 team before using this in any publications.

Hi Arpita, Just to confirm, you're looking at the formulas on page 4 of this paper, right? https://pubs.er.usgs.gov/publication/70034937 It looks like those are calculating the band depth (1 - R/Rc) at a number of adjacent bands, then adding them together to get the integrated band depth over a range of wavelengths; the variable 'n' is just used to indicate which bands are used in the calculation. So for the 1 micron integrated band depth, you'd calculate band depth at each of 789 nm, 809 nm, 829 nm, and so on, up to 1309 nm, and then add the results (with a similar calculation for 2 micron integrated band depth, just using different M3 bands in the sum). If you're using ENVI for your analysis, the Band Math tool should be able to help you calculate the band depth for each band that you're looking at, then sum up all of the results. John