[libcamera-devel] [PATCH 12/13] ipa: ipu3: agc: Increase IIR filter speed

[Jean-Michel Hautbois]

The filter used is an infinite response filter which is controlled by
the speed variable. It is used to limit the gap between two exposure
values, and avoid nasty oscillations. The higher the speed, the less the
result oscillates.

As we are only calculating the exposure every 6 frames, as controled by
the 'kFrameSkipCount' constant, we can increase the speed, to avoid a
slow response (it can be more than 1 second to get a stable enough
output).

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

diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp
index b922bcdf..81eaf436 100644
--- a/src/ipa/ipu3/algorithms/agc.cpp
+++ b/src/ipa/ipu3/algorithms/agc.cpp
@@ -92,7 +92,7 @@ void Agc::processBrightness(const ipu3_uapi_stats_3a *stats,
 
 void Agc::filterExposure()
 {
-	double speed = 0.2;
+	double speed = 0.9;
 	if (filteredExposure_ == 0s) {
 		/* DG stands for digital gain.*/
 		filteredExposure_ = currentExposure_;
-- 
2.30.2