[libcamera-devel] [PATCH 03/13] ipa: ipu3: awb: Use saturation under 90%

[Jean-Michel Hautbois]

The AWB grey world algorithm tries to find a grey value and it can't do
it on over-exposed images. To exclude those, the saturation ratio is
used for each cell, and the cell is included only if this ratio is 0.

Now that we have changed the threshold, more cells may be considered as
partially saturated and excluded, making the algorithm to not run.

Change that behaviour, and consider 90% as a good enough ratio.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
---
 src/ipa/ipu3/algorithms/awb.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/ipa/ipu3/algorithms/awb.cpp b/src/ipa/ipu3/algorithms/awb.cpp
index 5574bd44..30693923 100644
--- a/src/ipa/ipu3/algorithms/awb.cpp
+++ b/src/ipa/ipu3/algorithms/awb.cpp
@@ -161,6 +161,7 @@ int Awb::configure(IPAContext &context,
 	 * \todo This proportion could be configured.
 	 */
 	cellsPerZoneThreshold_ = cellsPerZoneX_ * cellsPerZoneY_ * 80 / 100;
+	LOG(IPU3Awb, Debug) << "Threshold for AWB is set to " << cellsPerZoneThreshold_;
 
 	return 0;
 }
@@ -232,7 +233,7 @@ void Awb::generateAwbStats(const ipu3_uapi_stats_3a *stats)
 				reinterpret_cast<const ipu3_uapi_awb_set_item *>(
 					&stats->awb_raw_buffer.meta_data[cellPosition]
 				);
-			if (currentCell->sat_ratio == 0) {
+			if (currentCell->sat_ratio <= 255 * 90 / 100) {
 				/* The cell is not saturated, use the current cell */
 				awbStats_[awbZonePosition].counted++;
 				uint32_t greenValue = currentCell->Gr_avg + currentCell->Gb_avg;
-- 
2.30.2