Hello, I am trying to use ENVI 5.5 in order to run CAI (Cellulose absorption index) and PSRI (Plant Senescence Reflectance Index) the hyperspectral data comes from AVIRIS and EO-1 hyperion. However, when these are run through band math only CAI works.

CAI If run through band math with the equation CAI= 0.5*(b1+b2)-b3 with b1 = p2000, b2 = p2200 and b3= p2100 every point show up as negative values in the hundreds. according to the index "The value of this index ranges from -3 to more than 4. The common range for green vegetation is -2 to 4." so this makes no sense. If run through Band algebra -> spectral indices we get the same thing. If run through Vegetation index calculator every point says "No Data".

PSRI if run through band math with the equation PSRI = (b1-b2)/b3 shows up as a white image with only water appearing in grey, and has 0 as the data for every point. If done through Spectral indices or vegetation index calculator we get values that make sense however in some points the psri calculated through vegetation index calculator shows "No data".

I am wondering how to make these indices work or how to manipulate the CAI data to fit in with the -3 to 4 scale that is mentioned in all other literature.

Thank you!