[libcamera-devel] [PATCH v4 01/14] ipa: ipu3: awb: Set a threshold for the green saturation
Jean-Michel Hautbois
jeanmichel.hautbois at ideasonboard.com
Fri Oct 22 09:32:36 CEST 2021
We can have a saturation ratio per cell, giving the percentage of pixels
over a threshold within a cell where 100% is set to 0xff.
The parameter structure 'ipu3_uapi_awb_config_s' contains four fields to
set the threshold, one per channel.
The blue field is also used to configure the ImgU and make it calculate
the saturation ratio or not.
Set a green value saturated when it is more than 230 (90% of the maximum
value 255, coded as 8191). As this is the only channel used for AGC,
there is no need to apply it to the other ones.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
---
src/ipa/ipu3/algorithms/awb.cpp | 27 +++++++++++++++++++++------
src/ipa/ipu3/algorithms/awb.h | 1 +
2 files changed, 22 insertions(+), 6 deletions(-)
diff --git a/src/ipa/ipu3/algorithms/awb.cpp b/src/ipa/ipu3/algorithms/awb.cpp
index 809de66a..4364928c 100644
--- a/src/ipa/ipu3/algorithms/awb.cpp
+++ b/src/ipa/ipu3/algorithms/awb.cpp
@@ -328,14 +328,29 @@ void Awb::process(IPAContext &context, const ipu3_uapi_stats_3a *stats)
context.frameContext.awb.gains.red = asyncResults_.redGain;
}
+constexpr uint16_t Awb::threshold(float value)
+{
+ /* AWB thresholds are in the range [0, 8191] */
+ return value * 8191;
+}
+
void Awb::prepare(IPAContext &context, ipu3_uapi_params *params)
{
- params->acc_param.awb.config.rgbs_thr_gr = 8191;
- params->acc_param.awb.config.rgbs_thr_r = 8191;
- params->acc_param.awb.config.rgbs_thr_gb = 8191;
- params->acc_param.awb.config.rgbs_thr_b = IPU3_UAPI_AWB_RGBS_THR_B_INCL_SAT
- | IPU3_UAPI_AWB_RGBS_THR_B_EN
- | 8191;
+ /*
+ * Green saturation thresholds are reduced because we are using the
+ * green channel only in the exposure computation.
+ */
+ params->acc_param.awb.config.rgbs_thr_r = threshold(1.0);
+ params->acc_param.awb.config.rgbs_thr_gr = threshold(0.9);
+ params->acc_param.awb.config.rgbs_thr_gb = threshold(0.9);
+ params->acc_param.awb.config.rgbs_thr_b = threshold(1.0);
+
+ /*
+ * Enable saturation inclusion on thr_b for ImgU to update the
+ * ipu3_uapi_awb_set_item->sat_ratio field.
+ */
+ params->acc_param.awb.config.rgbs_thr_b |= IPU3_UAPI_AWB_RGBS_THR_B_INCL_SAT |
+ IPU3_UAPI_AWB_RGBS_THR_B_EN;
const ipu3_uapi_grid_config &grid = context.configuration.grid.bdsGrid;
diff --git a/src/ipa/ipu3/algorithms/awb.h b/src/ipa/ipu3/algorithms/awb.h
index 3b81f600..0c81e39e 100644
--- a/src/ipa/ipu3/algorithms/awb.h
+++ b/src/ipa/ipu3/algorithms/awb.h
@@ -70,6 +70,7 @@ private:
void clearAwbStats();
void awbGreyWorld();
uint32_t estimateCCT(double red, double green, double blue);
+ static constexpr uint16_t threshold(float value);
std::vector<RGB> zones_;
Accumulator awbStats_[kAwbStatsSizeX * kAwbStatsSizeY];
--
2.32.0
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