diff options
Diffstat (limited to 'src/ipa/libipa/exposure_mode_helper.cpp')
| -rw-r--r-- | src/ipa/libipa/exposure_mode_helper.cpp | 152 |
1 files changed, 76 insertions, 76 deletions
diff --git a/src/ipa/libipa/exposure_mode_helper.cpp b/src/ipa/libipa/exposure_mode_helper.cpp index 30da0c89..f235316d 100644 --- a/src/ipa/libipa/exposure_mode_helper.cpp +++ b/src/ipa/libipa/exposure_mode_helper.cpp @@ -14,9 +14,9 @@ * \file exposure_mode_helper.h * \brief Helper class that performs computations relating to exposure * - * AEGC algorithms have a need to split exposure between shutter time, analogue + * AEGC algorithms have a need to split exposure between exposure time, analogue * and digital gain. Multiple implementations do so based on paired stages of - * shutter time and gain limits; provide a helper to avoid duplicating the code. + * exposure time and gain limits; provide a helper to avoid duplicating the code. */ namespace libcamera { @@ -29,24 +29,24 @@ namespace ipa { /** * \class ExposureModeHelper - * \brief Class for splitting exposure into shutter time and total gain + * \brief Class for splitting exposure into exposure time and total gain * * The ExposureModeHelper class provides a standard interface through which an - * AEGC algorithm can divide exposure between shutter time and gain. It is - * configured with a set of shutter time and gain pairs and works by initially - * fixing gain at 1.0 and increasing shutter time up to the shutter time value + * AEGC algorithm can divide exposure between exposure time and gain. It is + * configured with a set of exposure time and gain pairs and works by initially + * fixing gain at 1.0 and increasing exposure time up to the exposure time value * from the first pair in the set in an attempt to meet the required exposure * value. * - * If the required exposure is not achievable by the first shutter time value + * If the required exposure is not achievable by the first exposure time value * alone it ramps gain up to the value from the first pair in the set. If the - * required exposure is still not met it then allows shutter time to ramp up to - * the shutter time value from the second pair in the set, and continues in this + * required exposure is still not met it then allows exposure time to ramp up to + * the exposure time value from the second pair in the set, and continues in this * vein until either the required exposure time is met, or else the hardware's - * shutter time or gain limits are reached. + * exposure time or gain limits are reached. * * This method allows users to strike a balance between a well-exposed image and - * an acceptable frame-rate, as opposed to simply maximising shutter time + * an acceptable frame-rate, as opposed to simply maximising exposure time * followed by gain. The same helpers can be used to perform the latter * operation if needed by passing an empty set of pairs to the initialisation * function. @@ -61,9 +61,9 @@ namespace ipa { /** * \brief Construct an ExposureModeHelper instance - * \param[in] stages The vector of paired shutter time and gain limits + * \param[in] stages The vector of paired exposure time and gain limits * - * The input stages are shutter time and _total_ gain pairs; the gain + * The input stages are exposure time and _total_ gain pairs; the gain * encompasses both analogue and digital gain. * * The vector of stages may be empty. In that case, the helper will simply use @@ -71,46 +71,46 @@ namespace ipa { */ ExposureModeHelper::ExposureModeHelper(const Span<std::pair<utils::Duration, double>> stages) { - minShutter_ = 0us; - maxShutter_ = 0us; + minExposureTime_ = 0us; + maxExposureTime_ = 0us; minGain_ = 0; maxGain_ = 0; for (const auto &[s, g] : stages) { - shutters_.push_back(s); + exposureTimes_.push_back(s); gains_.push_back(g); } } /** - * \brief Set the shutter time and gain limits - * \param[in] minShutter The minimum shutter time supported - * \param[in] maxShutter The maximum shutter time supported + * \brief Set the exposure time and gain limits + * \param[in] minExposureTime The minimum exposure time supported + * \param[in] maxExposureTime The maximum exposure time supported * \param[in] minGain The minimum analogue gain supported * \param[in] maxGain The maximum analogue gain supported * - * This function configures the shutter time and analogue gain limits that need + * This function configures the exposure time and analogue gain limits that need * to be adhered to as the helper divides up exposure. Note that this function * *must* be called whenever those limits change and before splitExposure() is * used. * - * If the algorithm using the helpers needs to indicate that either shutter time + * If the algorithm using the helpers needs to indicate that either exposure time * or analogue gain or both should be fixed it can do so by setting both the * minima and maxima to the same value. */ -void ExposureModeHelper::setLimits(utils::Duration minShutter, - utils::Duration maxShutter, +void ExposureModeHelper::setLimits(utils::Duration minExposureTime, + utils::Duration maxExposureTime, double minGain, double maxGain) { - minShutter_ = minShutter; - maxShutter_ = maxShutter; + minExposureTime_ = minExposureTime; + maxExposureTime_ = maxExposureTime; minGain_ = minGain; maxGain_ = maxGain; } -utils::Duration ExposureModeHelper::clampShutter(utils::Duration shutter) const +utils::Duration ExposureModeHelper::clampExposureTime(utils::Duration exposureTime) const { - return std::clamp(shutter, minShutter_, maxShutter_); + return std::clamp(exposureTime, minExposureTime_, maxExposureTime_); } double ExposureModeHelper::clampGain(double gain) const @@ -119,108 +119,108 @@ double ExposureModeHelper::clampGain(double gain) const } /** - * \brief Split exposure time into shutter time and gain - * \param[in] exposure Exposure time + * \brief Split exposure into exposure time and gain + * \param[in] exposure Exposure value * - * This function divides a given exposure time into shutter time, analogue and - * digital gain by iterating through stages of shutter time and gain limits. At - * each stage the current stage's shutter time limit is multiplied by the + * This function divides a given exposure into exposure time, analogue and + * digital gain by iterating through stages of exposure time and gain limits. + * At each stage the current stage's exposure time limit is multiplied by the * previous stage's gain limit (or 1.0 initially) to see if the combination of - * the two can meet the required exposure time. If they cannot then the current - * stage's shutter time limit is multiplied by the same stage's gain limit to + * the two can meet the required exposure. If they cannot then the current + * stage's exposure time limit is multiplied by the same stage's gain limit to * see if that combination can meet the required exposure time. If they cannot * then the function moves to consider the next stage. * - * When a combination of shutter time and gain _stage_ limits are found that are - * sufficient to meet the required exposure time, the function attempts to - * reduce shutter time as much as possible whilst fixing gain and still meeting - * the exposure time. If a _runtime_ limit prevents shutter time from being - * lowered enough to meet the exposure time with gain fixed at the stage limit, - * gain is also lowered to compensate. + * When a combination of exposure time and gain _stage_ limits are found that + * are sufficient to meet the required exposure, the function attempts to reduce + * exposure time as much as possible whilst fixing gain and still meeting the + * exposure. If a _runtime_ limit prevents exposure time from being lowered + * enough to meet the exposure with gain fixed at the stage limit, gain is also + * lowered to compensate. * - * Once the shutter time and gain values are ascertained, gain is assigned as + * Once the exposure time and gain values are ascertained, gain is assigned as * analogue gain as much as possible, with digital gain only in use if the * maximum analogue gain runtime limit is unable to accommodate the exposure * value. * - * If no combination of shutter time and gain limits is found that meets the - * required exposure time, the helper falls-back to simply maximising the - * shutter time first, followed by analogue gain, followed by digital gain. + * If no combination of exposure time and gain limits is found that meets the + * required exposure, the helper falls-back to simply maximising the exposure + * time first, followed by analogue gain, followed by digital gain. * - * \return Tuple of shutter time, analogue gain, and digital gain + * \return Tuple of exposure time, analogue gain, and digital gain */ std::tuple<utils::Duration, double, double> ExposureModeHelper::splitExposure(utils::Duration exposure) const { - ASSERT(maxShutter_); + ASSERT(maxExposureTime_); ASSERT(maxGain_); bool gainFixed = minGain_ == maxGain_; - bool shutterFixed = minShutter_ == maxShutter_; + bool exposureTimeFixed = minExposureTime_ == maxExposureTime_; /* * There's no point entering the loop if we cannot change either gain - * nor shutter anyway. + * nor exposure time anyway. */ - if (shutterFixed && gainFixed) - return { minShutter_, minGain_, exposure / (minShutter_ * minGain_) }; + if (exposureTimeFixed && gainFixed) + return { minExposureTime_, minGain_, exposure / (minExposureTime_ * minGain_) }; - utils::Duration shutter; + utils::Duration exposureTime; double stageGain = 1.0; double gain; for (unsigned int stage = 0; stage < gains_.size(); stage++) { double lastStageGain = stage == 0 ? 1.0 : clampGain(gains_[stage - 1]); - utils::Duration stageShutter = clampShutter(shutters_[stage]); + utils::Duration stageExposureTime = clampExposureTime(exposureTimes_[stage]); stageGain = clampGain(gains_[stage]); /* - * We perform the clamping on both shutter and gain in case the - * helper has had limits set that prevent those values being - * lowered beyond a certain minimum...this can happen at runtime - * for various reasons and so would not be known when the stage - * limits are initialised. + * We perform the clamping on both exposure time and gain in + * case the helper has had limits set that prevent those values + * being lowered beyond a certain minimum...this can happen at + * runtime for various reasons and so would not be known when + * the stage limits are initialised. */ - if (stageShutter * lastStageGain >= exposure) { - shutter = clampShutter(exposure / clampGain(lastStageGain)); - gain = clampGain(exposure / shutter); + if (stageExposureTime * lastStageGain >= exposure) { + exposureTime = clampExposureTime(exposure / clampGain(lastStageGain)); + gain = clampGain(exposure / exposureTime); - return { shutter, gain, exposure / (shutter * gain) }; + return { exposureTime, gain, exposure / (exposureTime * gain) }; } - if (stageShutter * stageGain >= exposure) { - shutter = clampShutter(exposure / clampGain(stageGain)); - gain = clampGain(exposure / shutter); + if (stageExposureTime * stageGain >= exposure) { + exposureTime = clampExposureTime(exposure / clampGain(stageGain)); + gain = clampGain(exposure / exposureTime); - return { shutter, gain, exposure / (shutter * gain) }; + return { exposureTime, gain, exposure / (exposureTime * gain) }; } } /* - * From here on all we can do is max out the shutter time, followed by + * From here on all we can do is max out the exposure time, followed by * the analogue gain. If we still haven't achieved the target we send * the rest of the exposure time to digital gain. If we were given no * stages to use then the default stageGain of 1.0 is used so that - * shutter time is maxed before gain is touched at all. + * exposure time is maxed before gain is touched at all. */ - shutter = clampShutter(exposure / clampGain(stageGain)); - gain = clampGain(exposure / shutter); + exposureTime = clampExposureTime(exposure / clampGain(stageGain)); + gain = clampGain(exposure / exposureTime); - return { shutter, gain, exposure / (shutter * gain) }; + return { exposureTime, gain, exposure / (exposureTime * gain) }; } /** - * \fn ExposureModeHelper::minShutter() - * \brief Retrieve the configured minimum shutter time limit set through + * \fn ExposureModeHelper::minExposureTime() + * \brief Retrieve the configured minimum exposure time limit set through * setLimits() - * \return The minShutter_ value + * \return The minExposureTime_ value */ /** - * \fn ExposureModeHelper::maxShutter() - * \brief Retrieve the configured maximum shutter time set through setLimits() - * \return The maxShutter_ value + * \fn ExposureModeHelper::maxExposureTime() + * \brief Retrieve the configured maximum exposure time set through setLimits() + * \return The maxExposureTime_ value */ /** |