I have some polygons and I want to extract the spectral signature of the adjacent satellite images. The satellite images that i use are the NDVI from Landsat 7 and 8 and I want to compare the spectral signature of them. I use both ENVI 5.03 and Arcgis 10.2. Is enough to extract the values from the pixels?
with ArcGIS you can use "zonal statistics as a table" to extract the mean spectral values for each band and within your polygon. You can run it in batch mode (right click on the tools > batch) to have the values related to each band of each satellite.
With ENVI you can use the ROI tools
I'd do something like this using R and raster package
Do the same for OLI
Proceed with comparisons, handling data from sigs data.frame.
Please let me know if you need help to go further with the analysis.