How are Radiances calculated?
The values given for GAIN and BIAS in the header are
not the GAIN and BIAS as expected. These
values are L_min and L_max,
given in units of mW/(cm*cm)/str/micron,
where BIAS is L_min and GAIN is L_max.
L_rad = ------- * ( L_max - L_min ) + L_min
L_rad is the radiance
G_max = (2 ^ Q) - 1
Exception: G_max = 255 for IRS-1C and IRS-1D radiometrically corrected and higher level products.
L_max is the maximum saturation radiance
L_min is the minimum saturation radiance
D is the DN from the image
Q is the number of quantisation bits of the sensor