I'm working with a mapir nir + red camera meaning that its blue band captures nir light and its red captures red normally. I understand that NDVI is calculated using reflectance values.
How do I convert 8 bit RGB into reflectance values so that I'm able to calculate each NDVI value? Also, does converting an image to grayscale mean its reflectance?
Best Answer
Please go through this page:
https://landsat.usgs.gov/using-usgs-landsat-8-product
This clearly tells you how to convert a DN value to reflectance. The important point to consider are multiplicative and additive re-scaling factor. As you'll clearly see, either these values are known to you (through metadata) or need to be calculated through more esoteric methods. It seems maybe the values are with OEM. If not, then there is no immediate way to convert DN values to reflectance.