diff options
Diffstat (limited to 'src/ipa/rpi/controller/rpi/agc_channel.cpp')
| -rw-r--r-- | src/ipa/rpi/controller/rpi/agc_channel.cpp | 1022 |
1 files changed, 1022 insertions, 0 deletions
diff --git a/src/ipa/rpi/controller/rpi/agc_channel.cpp b/src/ipa/rpi/controller/rpi/agc_channel.cpp new file mode 100644 index 00000000..8116c6c1 --- /dev/null +++ b/src/ipa/rpi/controller/rpi/agc_channel.cpp @@ -0,0 +1,1022 @@ +/* SPDX-License-Identifier: BSD-2-Clause */ +/* + * Copyright (C) 2023, Raspberry Pi Ltd + * + * agc_channel.cpp - AGC/AEC control algorithm + */ + +#include "agc_channel.h" + +#include <algorithm> +#include <tuple> + +#include <libcamera/base/log.h> + +#include "../awb_status.h" +#include "../device_status.h" +#include "../histogram.h" +#include "../lux_status.h" +#include "../metadata.h" + +using namespace RPiController; +using namespace libcamera; +using libcamera::utils::Duration; +using namespace std::literals::chrono_literals; + +LOG_DECLARE_CATEGORY(RPiAgc) + +int AgcMeteringMode::read(const libcamera::YamlObject ¶ms) +{ + const YamlObject &yamlWeights = params["weights"]; + + for (const auto &p : yamlWeights.asList()) { + auto value = p.get<double>(); + if (!value) + return -EINVAL; + weights.push_back(*value); + } + + return 0; +} + +static std::tuple<int, std::string> +readMeteringModes(std::map<std::string, AgcMeteringMode> &metering_modes, + const libcamera::YamlObject ¶ms) +{ + std::string first; + int ret; + + for (const auto &[key, value] : params.asDict()) { + AgcMeteringMode meteringMode; + ret = meteringMode.read(value); + if (ret) + return { ret, {} }; + + metering_modes[key] = std::move(meteringMode); + if (first.empty()) + first = key; + } + + return { 0, first }; +} + +int AgcExposureMode::read(const libcamera::YamlObject ¶ms) +{ + auto value = params["shutter"].getList<double>(); + if (!value) + return -EINVAL; + std::transform(value->begin(), value->end(), std::back_inserter(shutter), + [](double v) { return v * 1us; }); + + value = params["gain"].getList<double>(); + if (!value) + return -EINVAL; + gain = std::move(*value); + + if (shutter.size() < 2 || gain.size() < 2) { + LOG(RPiAgc, Error) + << "AgcExposureMode: must have at least two entries in exposure profile"; + return -EINVAL; + } + + if (shutter.size() != gain.size()) { + LOG(RPiAgc, Error) + << "AgcExposureMode: expect same number of exposure and gain entries in exposure profile"; + return -EINVAL; + } + + return 0; +} + +static std::tuple<int, std::string> +readExposureModes(std::map<std::string, AgcExposureMode> &exposureModes, + const libcamera::YamlObject ¶ms) +{ + std::string first; + int ret; + + for (const auto &[key, value] : params.asDict()) { + AgcExposureMode exposureMode; + ret = exposureMode.read(value); + if (ret) + return { ret, {} }; + + exposureModes[key] = std::move(exposureMode); + if (first.empty()) + first = key; + } + + return { 0, first }; +} + +int AgcConstraint::read(const libcamera::YamlObject ¶ms) +{ + std::string boundString = params["bound"].get<std::string>(""); + transform(boundString.begin(), boundString.end(), + boundString.begin(), ::toupper); + if (boundString != "UPPER" && boundString != "LOWER") { + LOG(RPiAgc, Error) << "AGC constraint type should be UPPER or LOWER"; + return -EINVAL; + } + bound = boundString == "UPPER" ? Bound::UPPER : Bound::LOWER; + + auto value = params["q_lo"].get<double>(); + if (!value) + return -EINVAL; + qLo = *value; + + value = params["q_hi"].get<double>(); + if (!value) + return -EINVAL; + qHi = *value; + + return yTarget.read(params["y_target"]); +} + +static std::tuple<int, AgcConstraintMode> +readConstraintMode(const libcamera::YamlObject ¶ms) +{ + AgcConstraintMode mode; + int ret; + + for (const auto &p : params.asList()) { + AgcConstraint constraint; + ret = constraint.read(p); + if (ret) + return { ret, {} }; + + mode.push_back(std::move(constraint)); + } + + return { 0, mode }; +} + +static std::tuple<int, std::string> +readConstraintModes(std::map<std::string, AgcConstraintMode> &constraintModes, + const libcamera::YamlObject ¶ms) +{ + std::string first; + int ret; + + for (const auto &[key, value] : params.asDict()) { + std::tie(ret, constraintModes[key]) = readConstraintMode(value); + if (ret) + return { ret, {} }; + + if (first.empty()) + first = key; + } + + return { 0, first }; +} + +int AgcChannelConstraint::read(const libcamera::YamlObject ¶ms) +{ + auto channelValue = params["channel"].get<unsigned int>(); + if (!channelValue) { + LOG(RPiAgc, Error) << "AGC channel constraint must have a channel"; + return -EINVAL; + } + channel = *channelValue; + + std::string boundString = params["bound"].get<std::string>(""); + transform(boundString.begin(), boundString.end(), + boundString.begin(), ::toupper); + if (boundString != "UPPER" && boundString != "LOWER") { + LOG(RPiAgc, Error) << "AGC channel constraint type should be UPPER or LOWER"; + return -EINVAL; + } + bound = boundString == "UPPER" ? Bound::UPPER : Bound::LOWER; + + auto factorValue = params["factor"].get<double>(); + if (!factorValue) { + LOG(RPiAgc, Error) << "AGC channel constraint must have a factor"; + return -EINVAL; + } + factor = *factorValue; + + return 0; +} + +static int readChannelConstraints(std::vector<AgcChannelConstraint> &channelConstraints, + const libcamera::YamlObject ¶ms) +{ + for (const auto &p : params.asList()) { + AgcChannelConstraint constraint; + int ret = constraint.read(p); + if (ret) + return ret; + + channelConstraints.push_back(constraint); + } + + return 0; +} + +int AgcConfig::read(const libcamera::YamlObject ¶ms) +{ + LOG(RPiAgc, Debug) << "AgcConfig"; + int ret; + + std::tie(ret, defaultMeteringMode) = + readMeteringModes(meteringModes, params["metering_modes"]); + if (ret) + return ret; + std::tie(ret, defaultExposureMode) = + readExposureModes(exposureModes, params["exposure_modes"]); + if (ret) + return ret; + std::tie(ret, defaultConstraintMode) = + readConstraintModes(constraintModes, params["constraint_modes"]); + if (ret) + return ret; + + if (params.contains("channel_constraints")) { + ret = readChannelConstraints(channelConstraints, params["channel_constraints"]); + if (ret) + return ret; + } + + ret = yTarget.read(params["y_target"]); + if (ret) + return ret; + + speed = params["speed"].get<double>(0.2); + startupFrames = params["startup_frames"].get<uint16_t>(10); + convergenceFrames = params["convergence_frames"].get<unsigned int>(6); + fastReduceThreshold = params["fast_reduce_threshold"].get<double>(0.4); + baseEv = params["base_ev"].get<double>(1.0); + + /* Start with quite a low value as ramping up is easier than ramping down. */ + defaultExposureTime = params["default_exposure_time"].get<double>(1000) * 1us; + defaultAnalogueGain = params["default_analogue_gain"].get<double>(1.0); + + stableRegion = params["stable_region"].get<double>(0.02); + + desaturate = params["desaturate"].get<int>(1); + + return 0; +} + +AgcChannel::ExposureValues::ExposureValues() + : shutter(0s), analogueGain(0), + totalExposure(0s), totalExposureNoDG(0s) +{ +} + +AgcChannel::AgcChannel() + : meteringMode_(nullptr), exposureMode_(nullptr), constraintMode_(nullptr), + frameCount_(0), lockCount_(0), + lastTargetExposure_(0s), ev_(1.0), flickerPeriod_(0s), + maxShutter_(0s), fixedShutter_(0s), fixedAnalogueGain_(0.0) +{ + /* Set AWB default values in case early frames have no updates in metadata. */ + awb_.gainR = 1.0; + awb_.gainG = 1.0; + awb_.gainB = 1.0; + + /* + * Setting status_.totalExposureValue_ to zero initially tells us + * it's not been calculated yet (i.e. Process hasn't yet run). + */ + status_ = {}; + status_.ev = ev_; +} + +int AgcChannel::read(const libcamera::YamlObject ¶ms, + const Controller::HardwareConfig &hardwareConfig) +{ + int ret = config_.read(params); + if (ret) + return ret; + + const Size &size = hardwareConfig.agcZoneWeights; + for (auto const &modes : config_.meteringModes) { + if (modes.second.weights.size() != size.width * size.height) { + LOG(RPiAgc, Error) << "AgcMeteringMode: Incorrect number of weights"; + return -EINVAL; + } + } + + /* + * Set the config's defaults (which are the first ones it read) as our + * current modes, until someone changes them. (they're all known to + * exist at this point) + */ + meteringModeName_ = config_.defaultMeteringMode; + meteringMode_ = &config_.meteringModes[meteringModeName_]; + exposureModeName_ = config_.defaultExposureMode; + exposureMode_ = &config_.exposureModes[exposureModeName_]; + constraintModeName_ = config_.defaultConstraintMode; + constraintMode_ = &config_.constraintModes[constraintModeName_]; + /* Set up the "last shutter/gain" values, in case AGC starts "disabled". */ + status_.shutterTime = config_.defaultExposureTime; + status_.analogueGain = config_.defaultAnalogueGain; + return 0; +} + +void AgcChannel::disableAuto() +{ + fixedShutter_ = status_.shutterTime; + fixedAnalogueGain_ = status_.analogueGain; +} + +void AgcChannel::enableAuto() +{ + fixedShutter_ = 0s; + fixedAnalogueGain_ = 0; +} + +unsigned int AgcChannel::getConvergenceFrames() const +{ + /* + * If shutter and gain have been explicitly set, there is no + * convergence to happen, so no need to drop any frames - return zero. + */ + if (fixedShutter_ && fixedAnalogueGain_) + return 0; + else + return config_.convergenceFrames; +} + +std::vector<double> const &AgcChannel::getWeights() const +{ + /* + * In case someone calls setMeteringMode and then this before the + * algorithm has run and updated the meteringMode_ pointer. + */ + auto it = config_.meteringModes.find(meteringModeName_); + if (it == config_.meteringModes.end()) + return meteringMode_->weights; + return it->second.weights; +} + +void AgcChannel::setEv(double ev) +{ + ev_ = ev; +} + +void AgcChannel::setFlickerPeriod(Duration flickerPeriod) +{ + flickerPeriod_ = flickerPeriod; +} + +void AgcChannel::setMaxShutter(Duration maxShutter) +{ + maxShutter_ = maxShutter; +} + +void AgcChannel::setFixedShutter(Duration fixedShutter) +{ + fixedShutter_ = fixedShutter; + /* Set this in case someone calls disableAuto() straight after. */ + status_.shutterTime = limitShutter(fixedShutter_); +} + +void AgcChannel::setFixedAnalogueGain(double fixedAnalogueGain) +{ + fixedAnalogueGain_ = fixedAnalogueGain; + /* Set this in case someone calls disableAuto() straight after. */ + status_.analogueGain = limitGain(fixedAnalogueGain); +} + +void AgcChannel::setMeteringMode(std::string const &meteringModeName) +{ + meteringModeName_ = meteringModeName; +} + +void AgcChannel::setExposureMode(std::string const &exposureModeName) +{ + exposureModeName_ = exposureModeName; +} + +void AgcChannel::setConstraintMode(std::string const &constraintModeName) +{ + constraintModeName_ = constraintModeName; +} + +void AgcChannel::switchMode(CameraMode const &cameraMode, + Metadata *metadata) +{ + /* AGC expects the mode sensitivity always to be non-zero. */ + ASSERT(cameraMode.sensitivity); + + housekeepConfig(); + + /* + * Store the mode in the local state. We must cache the sensitivity of + * of the previous mode for the calculations below. + */ + double lastSensitivity = mode_.sensitivity; + mode_ = cameraMode; + + Duration fixedShutter = limitShutter(fixedShutter_); + if (fixedShutter && fixedAnalogueGain_) { + /* We're going to reset the algorithm here with these fixed values. */ + fetchAwbStatus(metadata); + double minColourGain = std::min({ awb_.gainR, awb_.gainG, awb_.gainB, 1.0 }); + ASSERT(minColourGain != 0.0); + + /* This is the equivalent of computeTargetExposure and applyDigitalGain. */ + target_.totalExposureNoDG = fixedShutter_ * fixedAnalogueGain_; + target_.totalExposure = target_.totalExposureNoDG / minColourGain; + + /* Equivalent of filterExposure. This resets any "history". */ + filtered_ = target_; + + /* Equivalent of divideUpExposure. */ + filtered_.shutter = fixedShutter; + filtered_.analogueGain = fixedAnalogueGain_; + } else if (status_.totalExposureValue) { + /* + * On a mode switch, various things could happen: + * - the exposure profile might change + * - a fixed exposure or gain might be set + * - the new mode's sensitivity might be different + * We cope with the last of these by scaling the target values. After + * that we just need to re-divide the exposure/gain according to the + * current exposure profile, which takes care of everything else. + */ + + double ratio = lastSensitivity / cameraMode.sensitivity; + target_.totalExposureNoDG *= ratio; + target_.totalExposure *= ratio; + filtered_.totalExposureNoDG *= ratio; + filtered_.totalExposure *= ratio; + + divideUpExposure(); + } else { + /* + * We come through here on startup, when at least one of the shutter + * or gain has not been fixed. We must still write those values out so + * that they will be applied immediately. We supply some arbitrary defaults + * for any that weren't set. + */ + + /* Equivalent of divideUpExposure. */ + filtered_.shutter = fixedShutter ? fixedShutter : config_.defaultExposureTime; + filtered_.analogueGain = fixedAnalogueGain_ ? fixedAnalogueGain_ : config_.defaultAnalogueGain; + } + + writeAndFinish(metadata, false); +} + +void AgcChannel::prepare(Metadata *imageMetadata) +{ + Duration totalExposureValue = status_.totalExposureValue; + AgcStatus delayedStatus; + AgcPrepareStatus prepareStatus; + + /* Fetch the AWB status now because AWB also sets it in the prepare method. */ + fetchAwbStatus(imageMetadata); + + if (!imageMetadata->get("agc.delayed_status", delayedStatus)) + totalExposureValue = delayedStatus.totalExposureValue; + + prepareStatus.digitalGain = 1.0; + prepareStatus.locked = false; + + if (status_.totalExposureValue) { + /* Process has run, so we have meaningful values. */ + DeviceStatus deviceStatus; + if (imageMetadata->get("device.status", deviceStatus) == 0) { + Duration actualExposure = deviceStatus.shutterSpeed * + deviceStatus.analogueGain; + if (actualExposure) { + double digitalGain = totalExposureValue / actualExposure; + LOG(RPiAgc, Debug) << "Want total exposure " << totalExposureValue; + /* + * Never ask for a gain < 1.0, and also impose + * some upper limit. Make it customisable? + */ + prepareStatus.digitalGain = std::max(1.0, std::min(digitalGain, 4.0)); + LOG(RPiAgc, Debug) << "Actual exposure " << actualExposure; + LOG(RPiAgc, Debug) << "Use digitalGain " << prepareStatus.digitalGain; + LOG(RPiAgc, Debug) << "Effective exposure " + << actualExposure * prepareStatus.digitalGain; + /* Decide whether AEC/AGC has converged. */ + prepareStatus.locked = updateLockStatus(deviceStatus); + } + } else + LOG(RPiAgc, Warning) << "AgcChannel: no device metadata"; + imageMetadata->set("agc.prepare_status", prepareStatus); + } +} + +void AgcChannel::process(StatisticsPtr &stats, DeviceStatus const &deviceStatus, + Metadata *imageMetadata, + const AgcChannelTotalExposures &channelTotalExposures) +{ + frameCount_++; + /* + * First a little bit of housekeeping, fetching up-to-date settings and + * configuration, that kind of thing. + */ + housekeepConfig(); + /* Get the current exposure values for the frame that's just arrived. */ + fetchCurrentExposure(deviceStatus); + /* Compute the total gain we require relative to the current exposure. */ + double gain, targetY; + computeGain(stats, imageMetadata, gain, targetY); + /* Now compute the target (final) exposure which we think we want. */ + computeTargetExposure(gain); + /* The results have to be filtered so as not to change too rapidly. */ + filterExposure(); + /* + * We may be asked to limit the exposure using other channels. If another channel + * determines our upper bound we may want to know this later. + */ + bool channelBound = applyChannelConstraints(channelTotalExposures); + /* + * Some of the exposure has to be applied as digital gain, so work out + * what that is. It also tells us whether it's trying to desaturate the image + * more quickly, which can only happen when another channel is not limiting us. + */ + bool desaturate = applyDigitalGain(gain, targetY, channelBound); + /* + * The last thing is to divide up the exposure value into a shutter time + * and analogue gain, according to the current exposure mode. + */ + divideUpExposure(); + /* Finally advertise what we've done. */ + writeAndFinish(imageMetadata, desaturate); +} + +bool AgcChannel::updateLockStatus(DeviceStatus const &deviceStatus) +{ + const double errorFactor = 0.10; /* make these customisable? */ + const int maxLockCount = 5; + /* Reset "lock count" when we exceed this multiple of errorFactor */ + const double resetMargin = 1.5; + + /* Add 200us to the exposure time error to allow for line quantisation. */ + Duration exposureError = lastDeviceStatus_.shutterSpeed * errorFactor + 200us; + double gainError = lastDeviceStatus_.analogueGain * errorFactor; + Duration targetError = lastTargetExposure_ * errorFactor; + + /* + * Note that we don't know the exposure/gain limits of the sensor, so + * the values we keep requesting may be unachievable. For this reason + * we only insist that we're close to values in the past few frames. + */ + if (deviceStatus.shutterSpeed > lastDeviceStatus_.shutterSpeed - exposureError && + deviceStatus.shutterSpeed < lastDeviceStatus_.shutterSpeed + exposureError && + deviceStatus.analogueGain > lastDeviceStatus_.analogueGain - gainError && + deviceStatus.analogueGain < lastDeviceStatus_.analogueGain + gainError && + status_.targetExposureValue > lastTargetExposure_ - targetError && + status_.targetExposureValue < lastTargetExposure_ + targetError) + lockCount_ = std::min(lockCount_ + 1, maxLockCount); + else if (deviceStatus.shutterSpeed < lastDeviceStatus_.shutterSpeed - resetMargin * exposureError || + deviceStatus.shutterSpeed > lastDeviceStatus_.shutterSpeed + resetMargin * exposureError || + deviceStatus.analogueGain < lastDeviceStatus_.analogueGain - resetMargin * gainError || + deviceStatus.analogueGain > lastDeviceStatus_.analogueGain + resetMargin * gainError || + status_.targetExposureValue < lastTargetExposure_ - resetMargin * targetError || + status_.targetExposureValue > lastTargetExposure_ + resetMargin * targetError) + lockCount_ = 0; + + lastDeviceStatus_ = deviceStatus; + lastTargetExposure_ = status_.targetExposureValue; + + LOG(RPiAgc, Debug) << "Lock count updated to " << lockCount_; + return lockCount_ == maxLockCount; +} + +void AgcChannel::housekeepConfig() +{ + /* First fetch all the up-to-date settings, so no one else has to do it. */ + status_.ev = ev_; + status_.fixedShutter = limitShutter(fixedShutter_); + status_.fixedAnalogueGain = fixedAnalogueGain_; + status_.flickerPeriod = flickerPeriod_; + LOG(RPiAgc, Debug) << "ev " << status_.ev << " fixedShutter " + << status_.fixedShutter << " fixedAnalogueGain " + << status_.fixedAnalogueGain; + /* + * Make sure the "mode" pointers point to the up-to-date things, if + * they've changed. + */ + if (meteringModeName_ != status_.meteringMode) { + auto it = config_.meteringModes.find(meteringModeName_); + if (it == config_.meteringModes.end()) { + LOG(RPiAgc, Warning) << "No metering mode " << meteringModeName_; + meteringModeName_ = status_.meteringMode; + } else { + meteringMode_ = &it->second; + status_.meteringMode = meteringModeName_; + } + } + if (exposureModeName_ != status_.exposureMode) { + auto it = config_.exposureModes.find(exposureModeName_); + if (it == config_.exposureModes.end()) { + LOG(RPiAgc, Warning) << "No exposure profile " << exposureModeName_; + exposureModeName_ = status_.exposureMode; + } else { + exposureMode_ = &it->second; + status_.exposureMode = exposureModeName_; + } + } + if (constraintModeName_ != status_.constraintMode) { + auto it = config_.constraintModes.find(constraintModeName_); + if (it == config_.constraintModes.end()) { + LOG(RPiAgc, Warning) << "No constraint list " << constraintModeName_; + constraintModeName_ = status_.constraintMode; + } else { + constraintMode_ = &it->second; + status_.constraintMode = constraintModeName_; + } + } + LOG(RPiAgc, Debug) << "exposureMode " + << exposureModeName_ << " constraintMode " + << constraintModeName_ << " meteringMode " + << meteringModeName_; +} + +void AgcChannel::fetchCurrentExposure(DeviceStatus const &deviceStatus) +{ + current_.shutter = deviceStatus.shutterSpeed; + current_.analogueGain = deviceStatus.analogueGain; + current_.totalExposure = 0s; /* this value is unused */ + current_.totalExposureNoDG = current_.shutter * current_.analogueGain; +} + +void AgcChannel::fetchAwbStatus(Metadata *imageMetadata) +{ + if (imageMetadata->get("awb.status", awb_) != 0) + LOG(RPiAgc, Debug) << "No AWB status found"; +} + +static double computeInitialY(StatisticsPtr &stats, AwbStatus const &awb, + std::vector<double> &weights, double gain) +{ + constexpr uint64_t maxVal = 1 << Statistics::NormalisationFactorPow2; + + /* + * If we have no AGC region stats, but do have a a Y histogram, use that + * directly to caluclate the mean Y value of the image. + */ + if (!stats->agcRegions.numRegions() && stats->yHist.bins()) { + /* + * When the gain is applied to the histogram, anything below minBin + * will scale up directly with the gain, but anything above that + * will saturate into the top bin. + */ + auto &hist = stats->yHist; + double minBin = std::min(1.0, 1.0 / gain) * hist.bins(); + double binMean = hist.interBinMean(0.0, minBin); + double numUnsaturated = hist.cumulativeFreq(minBin); + /* This term is from all the pixels that won't saturate. */ + double ySum = binMean * gain * numUnsaturated; + /* And add the ones that will saturate. */ + ySum += (hist.total() - numUnsaturated) * hist.bins(); + return ySum / hist.total() / hist.bins(); + } + + ASSERT(weights.size() == stats->agcRegions.numRegions()); + + /* + * Note that the weights are applied by the IPA to the statistics directly, + * before they are given to us here. + */ + double rSum = 0, gSum = 0, bSum = 0, pixelSum = 0; + for (unsigned int i = 0; i < stats->agcRegions.numRegions(); i++) { + auto ®ion = stats->agcRegions.get(i); + rSum += std::min<double>(region.val.rSum * gain, (maxVal - 1) * region.counted); + gSum += std::min<double>(region.val.gSum * gain, (maxVal - 1) * region.counted); + bSum += std::min<double>(region.val.bSum * gain, (maxVal - 1) * region.counted); + pixelSum += region.counted; + } + if (pixelSum == 0.0) { + LOG(RPiAgc, Warning) << "computeInitialY: pixelSum is zero"; + return 0; + } + + double ySum; + /* Factor in the AWB correction if needed. */ + if (stats->agcStatsPos == Statistics::AgcStatsPos::PreWb) { + ySum = rSum * awb.gainR * .299 + + gSum * awb.gainG * .587 + + bSum * awb.gainB * .114; + } else + ySum = rSum * .299 + gSum * .587 + bSum * .114; + + return ySum / pixelSum / (1 << 16); +} + +/* + * We handle extra gain through EV by adjusting our Y targets. However, you + * simply can't monitor histograms once they get very close to (or beyond!) + * saturation, so we clamp the Y targets to this value. It does mean that EV + * increases don't necessarily do quite what you might expect in certain + * (contrived) cases. + */ + +static constexpr double EvGainYTargetLimit = 0.9; + +static double constraintComputeGain(AgcConstraint &c, const Histogram &h, double lux, + double evGain, double &targetY) +{ + targetY = c.yTarget.eval(c.yTarget.domain().clip(lux)); + targetY = std::min(EvGainYTargetLimit, targetY * evGain); + double iqm = h.interQuantileMean(c.qLo, c.qHi); + return (targetY * h.bins()) / iqm; +} + +void AgcChannel::computeGain(StatisticsPtr &statistics, Metadata *imageMetadata, + double &gain, double &targetY) +{ + struct LuxStatus lux = {}; + lux.lux = 400; /* default lux level to 400 in case no metadata found */ + if (imageMetadata->get("lux.status", lux) != 0) + LOG(RPiAgc, Warning) << "No lux level found"; + const Histogram &h = statistics->yHist; + double evGain = status_.ev * config_.baseEv; + /* + * The initial gain and target_Y come from some of the regions. After + * that we consider the histogram constraints. + */ + targetY = config_.yTarget.eval(config_.yTarget.domain().clip(lux.lux)); + targetY = std::min(EvGainYTargetLimit, targetY * evGain); + + /* + * Do this calculation a few times as brightness increase can be + * non-linear when there are saturated regions. + */ + gain = 1.0; + for (int i = 0; i < 8; i++) { + double initialY = computeInitialY(statistics, awb_, meteringMode_->weights, gain); + double extraGain = std::min(10.0, targetY / (initialY + .001)); + gain *= extraGain; + LOG(RPiAgc, Debug) << "Initial Y " << initialY << " target " << targetY + << " gives gain " << gain; + if (extraGain < 1.01) /* close enough */ + break; + } + + for (auto &c : *constraintMode_) { + double newTargetY; + double newGain = constraintComputeGain(c, h, lux.lux, evGain, newTargetY); + LOG(RPiAgc, Debug) << "Constraint has target_Y " + << newTargetY << " giving gain " << newGain; + if (c.bound == AgcConstraint::Bound::LOWER && newGain > gain) { + LOG(RPiAgc, Debug) << "Lower bound constraint adopted"; + gain = newGain; + targetY = newTargetY; + } else if (c.bound == AgcConstraint::Bound::UPPER && newGain < gain) { + LOG(RPiAgc, Debug) << "Upper bound constraint adopted"; + gain = newGain; + targetY = newTargetY; + } + } + LOG(RPiAgc, Debug) << "Final gain " << gain << " (target_Y " << targetY << " ev " + << status_.ev << " base_ev " << config_.baseEv + << ")"; +} + +void AgcChannel::computeTargetExposure(double gain) +{ + if (status_.fixedShutter && status_.fixedAnalogueGain) { + /* + * When ag and shutter are both fixed, we need to drive the + * total exposure so that we end up with a digital gain of at least + * 1/minColourGain. Otherwise we'd desaturate channels causing + * white to go cyan or magenta. + */ + double minColourGain = std::min({ awb_.gainR, awb_.gainG, awb_.gainB, 1.0 }); + ASSERT(minColourGain != 0.0); + target_.totalExposure = + status_.fixedShutter * status_.fixedAnalogueGain / minColourGain; + } else { + /* + * The statistics reflect the image without digital gain, so the final + * total exposure we're aiming for is: + */ + target_.totalExposure = current_.totalExposureNoDG * gain; + /* The final target exposure is also limited to what the exposure mode allows. */ + Duration maxShutter = status_.fixedShutter + ? status_.fixedShutter + : exposureMode_->shutter.back(); + maxShutter = limitShutter(maxShutter); + Duration maxTotalExposure = + maxShutter * + (status_.fixedAnalogueGain != 0.0 + ? status_.fixedAnalogueGain + : exposureMode_->gain.back()); + target_.totalExposure = std::min(target_.totalExposure, maxTotalExposure); + } + LOG(RPiAgc, Debug) << "Target totalExposure " << target_.totalExposure; +} + +bool AgcChannel::applyChannelConstraints(const AgcChannelTotalExposures &channelTotalExposures) +{ + bool channelBound = false; + LOG(RPiAgc, Debug) + << "Total exposure before channel constraints " << filtered_.totalExposure; + + for (const auto &constraint : config_.channelConstraints) { + LOG(RPiAgc, Debug) + << "Check constraint: channel " << constraint.channel << " bound " + << (constraint.bound == AgcChannelConstraint::Bound::UPPER ? "UPPER" : "LOWER") + << " factor " << constraint.factor; + if (constraint.channel >= channelTotalExposures.size() || + !channelTotalExposures[constraint.channel]) { + LOG(RPiAgc, Debug) << "no such channel or no exposure available- skipped"; + continue; + } + + libcamera::utils::Duration limitExposure = + channelTotalExposures[constraint.channel] * constraint.factor; + LOG(RPiAgc, Debug) << "Limit exposure " << limitExposure; + if ((constraint.bound == AgcChannelConstraint::Bound::UPPER && + filtered_.totalExposure > limitExposure) || + (constraint.bound == AgcChannelConstraint::Bound::LOWER && + filtered_.totalExposure < limitExposure)) { + filtered_.totalExposure = limitExposure; + LOG(RPiAgc, Debug) << "Constraint applies"; + channelBound = true; + } else + LOG(RPiAgc, Debug) << "Constraint does not apply"; + } + + LOG(RPiAgc, Debug) + << "Total exposure after channel constraints " << filtered_.totalExposure; + + return channelBound; +} + +bool AgcChannel::applyDigitalGain(double gain, double targetY, bool channelBound) +{ + double minColourGain = std::min({ awb_.gainR, awb_.gainG, awb_.gainB, 1.0 }); + ASSERT(minColourGain != 0.0); + double dg = 1.0 / minColourGain; + /* + * I think this pipeline subtracts black level and rescales before we + * get the stats, so no need to worry about it. + */ + LOG(RPiAgc, Debug) << "after AWB, target dg " << dg << " gain " << gain + << " target_Y " << targetY; + /* + * Finally, if we're trying to reduce exposure but the target_Y is + * "close" to 1.0, then the gain computed for that constraint will be + * only slightly less than one, because the measured Y can never be + * larger than 1.0. When this happens, demand a large digital gain so + * that the exposure can be reduced, de-saturating the image much more + * quickly (and we then approach the correct value more quickly from + * below). + */ + bool desaturate = false; + if (config_.desaturate) + desaturate = !channelBound && + targetY > config_.fastReduceThreshold && gain < sqrt(targetY); + if (desaturate) + dg /= config_.fastReduceThreshold; + LOG(RPiAgc, Debug) << "Digital gain " << dg << " desaturate? " << desaturate; + filtered_.totalExposureNoDG = filtered_.totalExposure / dg; + LOG(RPiAgc, Debug) << "Target totalExposureNoDG " << filtered_.totalExposureNoDG; + return desaturate; +} + +void AgcChannel::filterExposure() +{ + double speed = config_.speed; + double stableRegion = config_.stableRegion; + + /* + * AGC adapts instantly if both shutter and gain are directly specified + * or we're in the startup phase. + */ + if ((status_.fixedShutter && status_.fixedAnalogueGain) || + frameCount_ <= config_.startupFrames) + speed = 1.0; + if (!filtered_.totalExposure) { + filtered_.totalExposure = target_.totalExposure; + } else if (filtered_.totalExposure * (1.0 - stableRegion) < target_.totalExposure && + filtered_.totalExposure * (1.0 + stableRegion) > target_.totalExposure) { + /* Total exposure must change by more than this or we leave it alone. */ + } else { + /* + * If close to the result go faster, to save making so many + * micro-adjustments on the way. (Make this customisable?) + */ + if (filtered_.totalExposure < 1.2 * target_.totalExposure && + filtered_.totalExposure > 0.8 * target_.totalExposure) + speed = sqrt(speed); + filtered_.totalExposure = speed * target_.totalExposure + + filtered_.totalExposure * (1.0 - speed); + } + LOG(RPiAgc, Debug) << "After filtering, totalExposure " << filtered_.totalExposure + << " no dg " << filtered_.totalExposureNoDG; +} + +void AgcChannel::divideUpExposure() +{ + /* + * Sending the fixed shutter/gain cases through the same code may seem + * unnecessary, but it will make more sense when extend this to cover + * variable aperture. + */ + Duration exposureValue = filtered_.totalExposureNoDG; + Duration shutterTime; + double analogueGain; + shutterTime = status_.fixedShutter ? status_.fixedShutter + : exposureMode_->shutter[0]; + shutterTime = limitShutter(shutterTime); + analogueGain = status_.fixedAnalogueGain != 0.0 ? status_.fixedAnalogueGain + : exposureMode_->gain[0]; + analogueGain = limitGain(analogueGain); + if (shutterTime * analogueGain < exposureValue) { + for (unsigned int stage = 1; + stage < exposureMode_->gain.size(); stage++) { + if (!status_.fixedShutter) { + Duration stageShutter = + limitShutter(exposureMode_->shutter[stage]); + if (stageShutter * analogueGain >= exposureValue) { + shutterTime = exposureValue / analogueGain; + break; + } + shutterTime = stageShutter; + } + if (status_.fixedAnalogueGain == 0.0) { + if (exposureMode_->gain[stage] * shutterTime >= exposureValue) { + analogueGain = exposureValue / shutterTime; + break; + } + analogueGain = exposureMode_->gain[stage]; + analogueGain = limitGain(analogueGain); + } + } + } + LOG(RPiAgc, Debug) << "Divided up shutter and gain are " << shutterTime << " and " + << analogueGain; + /* + * Finally adjust shutter time for flicker avoidance (require both + * shutter and gain not to be fixed). + */ + if (!status_.fixedShutter && !status_.fixedAnalogueGain && + status_.flickerPeriod) { + int flickerPeriods = shutterTime / status_.flickerPeriod; + if (flickerPeriods) { + Duration newShutterTime = flickerPeriods * status_.flickerPeriod; + analogueGain *= shutterTime / newShutterTime; + /* + * We should still not allow the ag to go over the + * largest value in the exposure mode. Note that this + * may force more of the total exposure into the digital + * gain as a side-effect. + */ + analogueGain = std::min(analogueGain, exposureMode_->gain.back()); + analogueGain = limitGain(analogueGain); + shutterTime = newShutterTime; + } + LOG(RPiAgc, Debug) << "After flicker avoidance, shutter " + << shutterTime << " gain " << analogueGain; + } + filtered_.shutter = shutterTime; + filtered_.analogueGain = analogueGain; +} + +void AgcChannel::writeAndFinish(Metadata *imageMetadata, bool desaturate) +{ + status_.totalExposureValue = filtered_.totalExposure; + status_.targetExposureValue = desaturate ? 0s : target_.totalExposure; + status_.shutterTime = filtered_.shutter; + status_.analogueGain = filtered_.analogueGain; + /* + * Write to metadata as well, in case anyone wants to update the camera + * immediately. + */ + imageMetadata->set("agc.status", status_); + LOG(RPiAgc, Debug) << "Output written, total exposure requested is " + << filtered_.totalExposure; + LOG(RPiAgc, Debug) << "Camera exposure update: shutter time " << filtered_.shutter + << " analogue gain " << filtered_.analogueGain; +} + +Duration AgcChannel::limitShutter(Duration shutter) +{ + /* + * shutter == 0 is a special case for fixed shutter values, and must pass + * through unchanged + */ + if (!shutter) + return shutter; + + shutter = std::clamp(shutter, mode_.minShutter, maxShutter_); + return shutter; +} + +double AgcChannel::limitGain(double gain) const +{ + /* + * Only limit the lower bounds of the gain value to what the sensor limits. + * The upper bound on analogue gain will be made up with additional digital + * gain applied by the ISP. + * + * gain == 0.0 is a special case for fixed shutter values, and must pass + * through unchanged + */ + if (!gain) + return gain; + + gain = std::max(gain, mode_.minAnalogueGain); + return gain; +} |