NekoCWD/libcamera
NekoCWD/libcamera
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages 7 Wiki Activity Actions

ipa: ipu3: agc: Remove the threshold for the histogram calculation

Browse source 
Until commit f8f07f9468 (ipa: ipu3: agc: Improve gain calculation)
the gain to apply on the exposure value was only using the histogram.
Now that the global brightness of the frame is estimated too, we don't
need to remove part of the saturated pixels from the equation anymore.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Jean-Michel Hautbois 2021-11-16 09:03:19 +01:00
parent 0d50a04cc9
commit d9a2a1f703
1 changed files with 9 additions and 23 deletions
Download patch file Download diff file Expand all files Collapse all files

32
src/ipa/ipu3/algorithms/agc.cpp
View file

@ -58,12 +58,6 @@ static constexpr uint32_t knumHistogramBins = 256;
/* Target value to reach for the top 2% of the histogram */
static constexpr double kEvGainTarget = 0.5;
/*
* Maximum ratio of saturated pixels in a cell for the cell to be considered
* non-saturated and counted by the AGC algorithm.
*/
static constexpr uint32_t kMinCellsPerZoneRatio = 255 * 20 / 100;
/* Number of frames to wait before calculating stats on minimum exposure */
static constexpr uint32_t kNumStartupFrames = 10;
@ -133,27 +127,19 @@ void Agc::measureBrightness(const ipu3_uapi_stats_3a *stats,
&stats->awb_raw_buffer.meta_data[cellPosition]
);
if (cell->sat_ratio <= kMinCellsPerZoneRatio) {
uint8_t gr = cell->Gr_avg;
uint8_t gb = cell->Gb_avg;
/*
* Store the average green value to estimate the
* brightness. Even the overexposed pixels are
* taken into account.
*/
hist[(gr + gb) / 2]++;
}
uint8_t gr = cell->Gr_avg;
uint8_t gb = cell->Gb_avg;
/*
* Store the average green value to estimate the
* brightness. Even the overexposed pixels are
* taken into account.
*/
hist[(gr + gb) / 2]++;
}
}
Histogram cumulativeHist = Histogram(Span<uint32_t>(hist));
/* Estimate the quantile mean of the top 2% of the histogram */
if (cumulativeHist.total() == 0) {
/* Force the value as histogram is empty */
iqMean_ = knumHistogramBins - 0.5;
} else {
iqMean_ = cumulativeHist.interQuantileMean(0.98, 1.0);
}
iqMean_ = Histogram(Span<uint32_t>(hist)).interQuantileMean(0.98, 1.0);
}
/**