ISP Processing and 24-bit Sensor Output

NVIDIA recommends the following programming to process 24-bit sensors: The exposure combination is done in the sensor to generate the 24-bit linear pixel values. Following the exposure combination, the sensor performs a PWL compression on the 24-bit linear values to generate the 12-bit compressed pixel values.

The PWL compression on 24-bit values in the sensor is such that when ISP applies a PWL decompression to retrieve 20-bit data, the 20-bit data are effectively the result of 24-bit linear data compressed by a power curve. The power curve is designed to preserve the dynamic range of the sensor.

All the blocks following the PWL decompression (linearization) block in ISP (specifically the statistics data: LAC0, LAC1, HIST0, HIST1, and FB) operate on the 20-bit compressed data.

Therefore, when using the statistics data, you can write software to linearize the data by using the inverse power-curve.

The semi-raw RGBFP16 output generated by ISP is also compressed using this power-curve. Obtain this linear data by writing the software to use the inverse power-curve.