diff options
Diffstat (limited to 'src/ipa/ipu3/algorithms/agc.cpp')
-rw-r--r-- | src/ipa/ipu3/algorithms/agc.cpp | 74 |
1 files changed, 40 insertions, 34 deletions
diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp index 8d6f18f6..a929085c 100644 --- a/src/ipa/ipu3/algorithms/agc.cpp +++ b/src/ipa/ipu3/algorithms/agc.cpp @@ -72,7 +72,7 @@ static constexpr double kRelativeLuminanceTarget = 0.16; Agc::Agc() : frameCount_(0), lineDuration_(0s), minShutterSpeed_(0s), - maxShutterSpeed_(0s), filteredExposure_(0s), currentExposure_(0s) + maxShutterSpeed_(0s), filteredExposure_(0s) { } @@ -143,33 +143,37 @@ double Agc::measureBrightness(const ipu3_uapi_stats_3a *stats, /** * \brief Apply a filter on the exposure value to limit the speed of changes + * \param[in] exposureValue The target exposure from the AGC algorithm + * + * The speed of the filter is adaptive, and will produce the target quicker + * during startup, or when the target exposure is within 20% of the most recent + * filter output. + * + * \return The filtered exposure */ -void Agc::filterExposure() +utils::Duration Agc::filterExposure(utils::Duration exposureValue) { double speed = 0.2; - /* Adapt instantly if we are in startup phase */ + /* Adapt instantly if we are in startup phase. */ if (frameCount_ < kNumStartupFrames) speed = 1.0; - if (filteredExposure_ == 0s) { - /* DG stands for digital gain.*/ - filteredExposure_ = currentExposure_; - } else { - /* - * If we are close to the desired result, go faster to avoid making - * multiple micro-adjustments. - * \todo Make this customisable? - */ - if (filteredExposure_ < 1.2 * currentExposure_ && - filteredExposure_ > 0.8 * currentExposure_) - speed = sqrt(speed); - - filteredExposure_ = speed * currentExposure_ + - filteredExposure_ * (1.0 - speed); - } + /* + * If we are close to the desired result, go faster to avoid making + * multiple micro-adjustments. + * \todo Make this customisable? + */ + if (filteredExposure_ < 1.2 * exposureValue && + filteredExposure_ > 0.8 * exposureValue) + speed = sqrt(speed); + + filteredExposure_ = speed * exposureValue + + filteredExposure_ * (1.0 - speed); - LOG(IPU3Agc, Debug) << "After filtering, total_exposure " << filteredExposure_; + LOG(IPU3Agc, Debug) << "After filtering, exposure " << filteredExposure_; + + return filteredExposure_; } /** @@ -213,27 +217,29 @@ void Agc::computeExposure(IPAFrameContext &frameContext, double yGain, * Calculate the current exposure value for the scene as the latest * exposure value applied multiplied by the new estimated gain. */ - currentExposure_ = effectiveExposureValue * evGain; + utils::Duration exposureValue = effectiveExposureValue * evGain; /* Clamp the exposure value to the min and max authorized */ utils::Duration maxTotalExposure = maxShutterSpeed_ * maxAnalogueGain_; - currentExposure_ = std::min(currentExposure_, maxTotalExposure); - LOG(IPU3Agc, Debug) << "Target total exposure " << currentExposure_ + exposureValue = std::min(exposureValue, maxTotalExposure); + LOG(IPU3Agc, Debug) << "Target total exposure " << exposureValue << ", maximum is " << maxTotalExposure; - /* \todo: estimate if we need to desaturate */ - filterExposure(); - - /* Divide the exposure value as new exposure and gain values */ - utils::Duration exposureValue = filteredExposure_; - utils::Duration shutterTime; + /* + * Filter the exposure. + * \todo: estimate if we need to desaturate + */ + exposureValue = filterExposure(exposureValue); /* - * Push the shutter time up to the maximum first, and only then - * increase the gain. - */ - shutterTime = std::clamp<utils::Duration>(exposureValue / minAnalogueGain_, - minShutterSpeed_, maxShutterSpeed_); + * Divide the exposure value as new exposure and gain values. + * + * Push the shutter time up to the maximum first, and only then + * increase the gain. + */ + utils::Duration shutterTime = + std::clamp<utils::Duration>(exposureValue / minAnalogueGain_, + minShutterSpeed_, maxShutterSpeed_); double stepGain = std::clamp(exposureValue / shutterTime, minAnalogueGain_, maxAnalogueGain_); LOG(IPU3Agc, Debug) << "Divided up shutter and gain are " |