From d0478c41f432b1c733f7a49ca35614017f3ec33e Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Mon, 28 Oct 2024 03:00:10 +0200 Subject: libcamera: Rename "shutter speed" to "exposure time" The terms "shutter" and "shutter speed" are used through libcamera to mean "exposure time". This is confusing, both due to "speed" being used as "time" while it should be the inverse (i.e. a maximum speed should correspond to the minimum time), and due to "shutter speed" and "exposure time" being used in different places with the same meaning. To improve clarity of the code base and the documentation, use "exposure time" consistently to replace "shutter speed". This rename highlighted another vocabulary issue in libcamera. The ExposureModeHelper::splitExposure() function used to document that it splits "exposure time into shutter time and gain". It has been reworded to "split exposure into exposure time and gain". That is not entirely satisfactory, as "exposure" has a defined meaning in photography (see https://en.wikipedia.org/wiki/Exposure_(photography)) that is not expressed as a duration. This issue if left to be addressed separately. Signed-off-by: Laurent Pinchart Reviewed-by: Naushir Patuck Acked-by: Kieran Bingham --- src/ipa/rkisp1/algorithms/agc.cpp | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) (limited to 'src/ipa/rkisp1/algorithms') diff --git a/src/ipa/rkisp1/algorithms/agc.cpp b/src/ipa/rkisp1/algorithms/agc.cpp index 301b7ec2..40e5a8f4 100644 --- a/src/ipa/rkisp1/algorithms/agc.cpp +++ b/src/ipa/rkisp1/algorithms/agc.cpp @@ -183,7 +183,7 @@ int Agc::configure(IPAContext &context, const IPACameraSensorInfo &configInfo) * except it's computed in the IPA and not here so we'd have to * recompute it. */ - context.activeState.agc.maxFrameDuration = context.configuration.sensor.maxShutterSpeed; + context.activeState.agc.maxFrameDuration = context.configuration.sensor.maxExposureTime; /* * Define the measurement window for AGC as a centered rectangle @@ -194,8 +194,8 @@ int Agc::configure(IPAContext &context, const IPACameraSensorInfo &configInfo) context.configuration.agc.measureWindow.h_size = 3 * configInfo.outputSize.width / 4; context.configuration.agc.measureWindow.v_size = 3 * configInfo.outputSize.height / 4; - setLimits(context.configuration.sensor.minShutterSpeed, - context.configuration.sensor.maxShutterSpeed, + setLimits(context.configuration.sensor.minExposureTime, + context.configuration.sensor.maxExposureTime, context.configuration.sensor.minAnalogueGain, context.configuration.sensor.maxAnalogueGain); @@ -424,12 +424,12 @@ void Agc::process(IPAContext &context, [[maybe_unused]] const uint32_t frame, [](uint32_t x) { return x >> 4; }); expMeans_ = { params->ae.exp_mean, context.hw->numAeCells }; - utils::Duration maxShutterSpeed = + utils::Duration maxExposureTime = std::clamp(frameContext.agc.maxFrameDuration, - context.configuration.sensor.minShutterSpeed, - context.configuration.sensor.maxShutterSpeed); - setLimits(context.configuration.sensor.minShutterSpeed, - maxShutterSpeed, + context.configuration.sensor.minExposureTime, + context.configuration.sensor.maxExposureTime); + setLimits(context.configuration.sensor.minExposureTime, + maxExposureTime, context.configuration.sensor.minAnalogueGain, context.configuration.sensor.maxAnalogueGain); @@ -442,20 +442,21 @@ void Agc::process(IPAContext &context, [[maybe_unused]] const uint32_t frame, double analogueGain = frameContext.sensor.gain; utils::Duration effectiveExposureValue = exposureTime * analogueGain; - utils::Duration shutterTime; + utils::Duration newExposureTime; double aGain, dGain; - std::tie(shutterTime, aGain, dGain) = + std::tie(newExposureTime, aGain, dGain) = calculateNewEv(frameContext.agc.constraintMode, frameContext.agc.exposureMode, hist, effectiveExposureValue); LOG(RkISP1Agc, Debug) - << "Divided up shutter, analogue gain and digital gain are " - << shutterTime << ", " << aGain << " and " << dGain; + << "Divided up exposure time, analogue gain and digital gain are " + << newExposureTime << ", " << aGain << " and " << dGain; IPAActiveState &activeState = context.activeState; /* Update the estimated exposure and gain. */ - activeState.agc.automatic.exposure = shutterTime / context.configuration.sensor.lineDuration; + activeState.agc.automatic.exposure = newExposureTime + / context.configuration.sensor.lineDuration; activeState.agc.automatic.gain = aGain; fillMetadata(context, frameContext, metadata); -- cgit v1.2.1