[libcamera-devel] [PATCH v1 3/7] ipa: ipu3: awb: Correct the gain multipliers

[Jean-Michel Hautbois]

The gains have a precision u3.13, range [0, 8) which means that a gain
multiplier value of 1.0 is represented as a multiplication by 8192 in
the ImgU. Correct the gains as this was misunderstood in the first
place.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
---
 src/ipa/ipu3/algorithms/awb.cpp | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/ipa/ipu3/algorithms/awb.cpp b/src/ipa/ipu3/algorithms/awb.cpp
index 9497a21b..60a5fc52 100644
--- a/src/ipa/ipu3/algorithms/awb.cpp
+++ b/src/ipa/ipu3/algorithms/awb.cpp
@@ -329,13 +329,12 @@ void Awb::prepare(IPAContext &context, ipu3_uapi_params *params)
 							* params->acc_param.bnr.opt_center.y_reset;
 	/*
 	 * Green gains should not be touched and considered 1.
-	 * Default is 16, so do not change it at all.
-	 * 4096 is the value for a gain of 1.0
+	 * 8192 is the multiplier for a gain of 1.0
 	 */
-	params->acc_param.bnr.wb_gains.gr = 16 * context.frameContext.awb.gains.green;
-	params->acc_param.bnr.wb_gains.r = 4096 * context.frameContext.awb.gains.red;
-	params->acc_param.bnr.wb_gains.b = 4096 * context.frameContext.awb.gains.blue;
-	params->acc_param.bnr.wb_gains.gb = 16 * context.frameContext.awb.gains.green;
+	params->acc_param.bnr.wb_gains.gr = 8192 * context.frameContext.awb.gains.green;
+	params->acc_param.bnr.wb_gains.r = 8192 * context.frameContext.awb.gains.red;
+	params->acc_param.bnr.wb_gains.b = 8192 * context.frameContext.awb.gains.blue;
+	params->acc_param.bnr.wb_gains.gb = 8192 * context.frameContext.awb.gains.green;
 
 	LOG(IPU3Awb, Debug) << "Color temperature estimated: " << asyncResults_.temperatureK;
 
-- 
2.30.2