SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
The input to the H3A module is 10-bit RAW data from the IPIPEIF. A 10-bit to 8-bit A-Law compression step can be enabled and disabled separately for the AF engine (the VISS_RAWFE_H3A_PCR[1] AF_ALAW_EN bit) and the AE/AWB engine (the VISS_RAWFE_H3A_PCR[17] AEW_ALAW_EN bit). A-Law compression offers added protection against overflowing the accumulators.
If the A-Law table is enabled, the output is 10 bits, with the upper two bits filled with 0.
For the AF process, a horizontal median filter can be enabled and disabled (the VISS_RAWFE_H3A_PCR[2] AF_MED_EN bit) before A-Law compression. This filter is useful for reducing temperature-induced noise. The horizontal median filter calculates the absolute difference between the current pixel (i) and pixel (i – 2), and between the current pixel (i) and pixel (i + 2). If the absolute difference exceeds a threshold, and the sign of the differences is the same, the average of pixel (i – 2) and pixel (i + 2) replaces pixel (i). The threshold of the horizontal median filter can be set in the VISS_RAWFE_H3A_PCR[10:3] MED_TH bit field.