[PATCH v3 14/16] ipa: rkisp1: Damp color temperature regulation

[Stefan Klug]

Damp the regulation of the color temperature with the same factor as the
gains.  Not damping the color temperature leads to visible flicker, as
the CCM changes too much.

Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

---

Changes in v2:
- Collected tags

Changes in v3:
- Dropped incorrect call to estimateCCT()
---
 src/ipa/rkisp1/algorithms/awb.cpp | 5 +++--
 src/ipa/rkisp1/algorithms/ccm.cpp | 4 ----
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/src/ipa/rkisp1/algorithms/awb.cpp b/src/ipa/rkisp1/algorithms/awb.cpp
index f5415a0bb99d..47b29725af51 100644
--- a/src/ipa/rkisp1/algorithms/awb.cpp
+++ b/src/ipa/rkisp1/algorithms/awb.cpp
@@ -317,8 +317,6 @@ void Awb::process(IPAContext &context,
 	RkISP1AwbStats awbStats{ rgbMeans };
 	AwbResult awbResult = awbAlgo_->calculateAwb(awbStats, frameContext.lux.lux);
 
-	activeState.awb.automatic.temperatureK = awbResult.colourTemperature;
-
 	/*
 	 * Clamp the gain values to the hardware, which expresses gains as Q2.8
 	 * unsigned integer values. Set the minimum just above zero to avoid
@@ -329,9 +327,12 @@ void Awb::process(IPAContext &context,
 
 	/* Filter the values to avoid oscillations. */
 	double speed = 0.2;
+	double ct = awbResult.colourTemperature;
+	ct = ct * speed + activeState.awb.automatic.temperatureK * (1 - speed);
 	awbResult.gains = awbResult.gains * speed +
 			  activeState.awb.automatic.gains * (1 - speed);
 
+	activeState.awb.automatic.temperatureK = static_cast<unsigned int>(ct);
 	activeState.awb.automatic.gains = awbResult.gains;
 
 	LOG(RkISP1Awb, Debug)
diff --git a/src/ipa/rkisp1/algorithms/ccm.cpp b/src/ipa/rkisp1/algorithms/ccm.cpp
index 3a96a5427bc6..de2b6fe775aa 100644
--- a/src/ipa/rkisp1/algorithms/ccm.cpp
+++ b/src/ipa/rkisp1/algorithms/ccm.cpp
@@ -142,10 +142,6 @@ void Ccm::prepare(IPAContext &context, const uint32_t frame,
 	}
 
 	uint32_t ct = frameContext.awb.temperatureK;
-	/*
-	 * \todo The colour temperature will likely be noisy, add filtering to
-	 * avoid updating the CCM matrix all the time.
-	 */
 	if (frame > 0 && ct == ct_) {
 		frameContext.ccm.ccm = context.activeState.ccm.automatic;
 		return;
-- 
2.43.0