8.4 Radiometry Modes
The Lepton 2.5 release includes multiple options for radiometry modes that affect the video output signal:
Radiometry enabled, TLinear enabled (default)
Radiometry enabled, TLinear disabled
Radiometry disabled
The radiometry enabled mode affects the transfer function between incident flux (scene temperature) and pixel output. From an image-quality standpoint, both radiometry modes produce nearly identical performance (no change in NEDT), and either mode is appropriate for strict imaging applications. However, for applications in which temperature measurement is required, radiometry must be enabled to access the related calibration and software features, such as TLinear and spotmeter, which support these measurements. In radiometry enabled mode, enabling the corresponding TLinear mode changes the pixel output from representing scene flux in 14-bit digital counts to representing scene temperature values in Kelvin (multiplied by a scale factor to include decimals). For example, with TLinear mode enabled with a resolution of 0.01, a pixel value of 30000 signifies that the pixel is measuring 26.85°C (300.00K - 273.15K). The Lepton 2.5 configuration is intended as a fully radiometric release, therefore the factory defaults are defined to have both radiometry and TLinear modes enabled.
Temperature T = slope * (raw - 8192) + ambTemp
According to Max Ritter's work, the slope he calculated is 0.0217. I recorded the temperature of the difference between raw data and 8192 and the temperature measured by the MLX90614 to apply a polyfit using Matlab and I found the slope I got was 0.026. The result might vary when the environment temperature changes.How do you get temperature readings from the Lepton thermal images?? In degrees Celcius?