Calibration

By default, LeanHRPT calibrates all visible channels on NOAA, MetOp and FengYun and thermal channels on NOAA.

• Calibrated Visible channels represent a range of 0 through 100% albedo with black through white.
• Calibrated IR channels represents a range of -100 through 60°C with white through black.

AVHRR

The AVHRR is divided into two separate ranges, where 0-25% is 0-500 counts on visible channels but 0-12.5% on SWIR (this is why uncalibrated 321 on MetOp doesn't look right, calibration fixes this). Because of the two separate ranges, two sets of calibration coefficients are needed - so called "High" and "Low" - with a cutoff point somewhere around 500 (the dividing marker).

The latest coefficients can be found at https://www.ospo.noaa.gov/Products/ppp/notices.html.

VIRR

The VIRR is simply calibrated by doing linear brightness correction.

MSU-MR

LeanHRPT does not currently support calibration of the MSU-MR's visible channels.