Spectral indices in remote sensing- part-1

Spectral Indices (SIs) are mathematical equations applied to each pixel image to highlight a specific phenomenon on the ground. Most SIs are computed from the reflectance data produced after some pre-processing stages of multispectral remote sensing images. In which bx and by are the reflectance values of a pixel in bands x and y. If we calculate the value of a SI for each pixel, we can generate an image from SI. In this post, I want to talk about the two most important spectral indices and how to calculate them for a case study in the center of Rome, Italy, using the Sentinel-hub cloud platform.