[libcamera-devel] [PATCH v4 09/14] ipa: ipu3: agc: Use exposure in time for storage
Paul Elder
paul.elder at ideasonboard.com
Sat Nov 13 00:18:16 CET 2021
Hi Jean-Michel,
imo the subject could be a bit more clear:
"Store exposure in units of time"
On Thu, Nov 11, 2021 at 03:09:23PM +0100, Jean-Michel Hautbois wrote:
> The minimum and maximum exposure are stored in lines. Replace it by
> values in time to simplify the calculations.
>
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> ---
> src/ipa/ipu3/algorithms/agc.cpp | 21 +++++++++------------
> src/ipa/ipu3/algorithms/agc.h | 4 ++--
> 2 files changed, 11 insertions(+), 14 deletions(-)
>
> diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp
> index d736f21c..86b71886 100644
> --- a/src/ipa/ipu3/algorithms/agc.cpp
> +++ b/src/ipa/ipu3/algorithms/agc.cpp
> @@ -79,8 +79,8 @@ static constexpr uint32_t kMaxLuminance = 255;
> static constexpr double kNormalizedLumaTarget = 0.16;
>
> Agc::Agc()
> - : frameCount_(0), iqMean_(0.0), lineDuration_(0s), minExposureLines_(0),
> - maxExposureLines_(0), filteredExposure_(0s), currentExposure_(0s)
> + : frameCount_(0), iqMean_(0.0), lineDuration_(0s), minShutterSpeed_(0s),
> + maxShutterSpeed_(0s), filteredExposure_(0s), currentExposure_(0s)
To me it sounds a bit strange that speed is measured in seconds, but oh
well :p
Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>
> {
> }
>
> @@ -99,17 +99,16 @@ int Agc::configure(IPAContext &context, const IPAConfigInfo &configInfo)
> lineDuration_ = configInfo.sensorInfo.lineLength * 1.0s
> / configInfo.sensorInfo.pixelRate;
>
> - /* \todo replace the exposure in lines storage with time based ones. */
> - minExposureLines_ = context.configuration.agc.minShutterSpeed / lineDuration_;
> - maxExposureLines_ = std::min(context.configuration.agc.maxShutterSpeed / lineDuration_,
> - kMaxShutterSpeed / lineDuration_);
> + minShutterSpeed_ = context.configuration.agc.minShutterSpeed;
> + maxShutterSpeed_ = std::min(context.configuration.agc.maxShutterSpeed,
> + kMaxShutterSpeed);
>
> minAnalogueGain_ = std::max(context.configuration.agc.minAnalogueGain, kMinAnalogueGain);
> maxAnalogueGain_ = std::min(context.configuration.agc.maxAnalogueGain, kMaxAnalogueGain);
>
> /* Configure the default exposure and gain. */
> context.frameContext.agc.gain = minAnalogueGain_;
> - context.frameContext.agc.exposure = minExposureLines_;
> + context.frameContext.agc.exposure = minShutterSpeed_ / lineDuration_;
>
> return 0;
> }
> @@ -242,11 +241,9 @@ void Agc::computeExposure(IPAFrameContext &frameContext, double currentYGain)
> * exposure value applied multiplied by the new estimated gain.
> */
> currentExposure_ = effectiveExposureValue * evGain;
> - utils::Duration minShutterSpeed = minExposureLines_ * lineDuration_;
> - utils::Duration maxShutterSpeed = maxExposureLines_ * lineDuration_;
>
> /* Clamp the exposure value to the min and max authorized */
> - utils::Duration maxTotalExposure = maxShutterSpeed * maxAnalogueGain_;
> + utils::Duration maxTotalExposure = maxShutterSpeed_ * maxAnalogueGain_;
> currentExposure_ = std::min(currentExposure_, maxTotalExposure);
> LOG(IPU3Agc, Debug) << "Target total exposure " << currentExposure_
> << ", maximum is " << maxTotalExposure;
> @@ -256,14 +253,14 @@ void Agc::computeExposure(IPAFrameContext &frameContext, double currentYGain)
>
> /* Divide the exposure value as new exposure and gain values */
> utils::Duration exposureValue = filteredExposure_;
> - utils::Duration shutterTime = minShutterSpeed;
> + utils::Duration shutterTime;
>
> /*
> * Push the shutter time up to the maximum first, and only then
> * increase the gain.
> */
> shutterTime = std::clamp<utils::Duration>(exposureValue / minAnalogueGain_,
> - minShutterSpeed, maxShutterSpeed);
> + minShutterSpeed_, maxShutterSpeed_);
> double stepGain = std::clamp(exposureValue / shutterTime,
> minAnalogueGain_, maxAnalogueGain_);
> LOG(IPU3Agc, Debug) << "Divided up shutter and gain are "
> diff --git a/src/ipa/ipu3/algorithms/agc.h b/src/ipa/ipu3/algorithms/agc.h
> index 1d085b40..f14d56b7 100644
> --- a/src/ipa/ipu3/algorithms/agc.h
> +++ b/src/ipa/ipu3/algorithms/agc.h
> @@ -46,8 +46,8 @@ private:
> double iqMean_;
>
> utils::Duration lineDuration_;
> - uint32_t minExposureLines_;
> - uint32_t maxExposureLines_;
> + utils::Duration minShutterSpeed_;
> + utils::Duration maxShutterSpeed_;
>
> double minAnalogueGain_;
> double maxAnalogueGain_;
> --
> 2.32.0
>
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