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authorNick Hollinghurst <nick.hollinghurst@raspberrypi.com>2023-01-23 15:49:31 +0000
committerKieran Bingham <kieran.bingham@ideasonboard.com>2023-01-30 16:30:44 +0000
commitcc010b0c35bfa0eee0bafba6a5803d1405542456 (patch)
tree5e1179f74abe4f4eca76fa5f6eb3e541f4e2133f /src/ipa/raspberrypi/controller/rpi/af.h
parent8418473c5178c112d279d7b9ffab3a61f6306693 (diff)
ipa: raspberrypi: First version of autofocus algorithm using PDAF
Provide the first version of the Raspberry Pi autofocus algorithm. This implementation uses a hybrid of contrast detect autofocus (CDAF) and phase detect autofocus (PDAF) statistics. PDAF is always preferred over CDAF due to having less "hunting" behavior. Signed-off-by: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com> Signed-off-by: Naushir Patuck <naush@raspberrypi.com> Reviewed-by: Naushir Patuck <naush@raspberrypi.com> Reviewed-by: David Plowman <david.plowman@raspberrypi.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2022-2023, Raspberry Pi Ltd
+ *
+ * af.h - Autofocus control algorithm
+ */
+#pragma once
+
+#include "../af_algorithm.h"
+#include "../af_status.h"
+#include "../pdaf_data.h"
+#include "../pwl.h"
+
+/*
+ * This algorithm implements a hybrid of CDAF and PDAF, favouring PDAF.
+ *
+ * Whenever PDAF is available, it is used in a continuous feedback loop.
+ * When triggered in auto mode, we simply enable AF for a limited number
+ * of frames (it may terminate early if the delta becomes small enough).
+ *
+ * When PDAF confidence is low (due e.g. to low contrast or extreme defocus)
+ * or PDAF data are absent, fall back to CDAF with a programmed scan pattern.
+ * A coarse and fine scan are performed, using ISP's CDAF focus FoM to
+ * estimate the lens position with peak contrast. This is slower due to
+ * extra latency in the ISP, and requires a settling time between steps.
+ *
+ * Some hysteresis is applied to the switch between PDAF and CDAF, to avoid
+ * "nuisance" scans. During each interval where PDAF is not working, only
+ * ONE scan will be performed; CAF cannot track objects using CDAF alone.
+ *
+ * This algorithm is unrelated to "rpi.focus" which merely reports CDAF FoM.
+ */
+
+namespace RPiController {
+
+class Af : public AfAlgorithm
+{
+public:
+ Af(Controller *controller = NULL);
+ ~Af();
+ char const *name() const override;
+ int read(const libcamera::YamlObject &params) override;
+ void initialise() override;
+
+ /* IPA calls */
+ void switchMode(CameraMode const &cameraMode, Metadata *metadata) override;
+ void prepare(Metadata *imageMetadata) override;
+ void process(StatisticsPtr &stats, Metadata *imageMetadata) override;
+
+ /* controls */
+ void setRange(AfRange range) override;
+ void setSpeed(AfSpeed speed) override;
+ void setMetering(bool use_windows) override;
+ void setWindows(libcamera::Span<libcamera::Rectangle const> const &wins) override;
+ void setMode(AfMode mode) override;
+ AfMode getMode() const override;
+ bool setLensPosition(double dioptres, int32_t *hwpos) override;
+ std::optional<double> getLensPosition() const override;
+ void triggerScan() override;
+ void cancelScan() override;
+ void pause(AfPause pause) override;
+
+private:
+ enum class ScanState {
+ Idle = 0,
+ Trigger,
+ Pdaf,
+ Coarse,
+ Fine,
+ Settle
+ };
+
+ struct RangeDependentParams {
+ double focusMin; /* lower (far) limit in dipotres */
+ double focusMax; /* upper (near) limit in dioptres */
+ double focusDefault; /* default setting ("hyperfocal") */
+
+ RangeDependentParams();
+ void read(const libcamera::YamlObject &params);
+ };
+
+ struct SpeedDependentParams {
+ double stepCoarse; /* used for scans */
+ double stepFine; /* used for scans */
+ double contrastRatio; /* used for scan termination and reporting */
+ double pdafGain; /* coefficient for PDAF feedback loop */
+ double pdafSquelch; /* PDAF stability parameter (device-specific) */
+ double maxSlew; /* limit for lens movement per frame */
+ uint32_t pdafFrames; /* number of iterations when triggered */
+ uint32_t dropoutFrames; /* number of non-PDAF frames to switch to CDAF */
+ uint32_t stepFrames; /* frames to skip in between steps of a scan */
+
+ SpeedDependentParams();
+ void read(const libcamera::YamlObject &params);
+ };
+
+ struct CfgParams {
+ RangeDependentParams ranges[AfRangeMax];
+ SpeedDependentParams speeds[AfSpeedMax];
+ uint32_t confEpsilon; /* PDAF hysteresis threshold (sensor-specific) */
+ uint32_t confThresh; /* PDAF confidence cell min (sensor-specific) */
+ uint32_t confClip; /* PDAF confidence cell max (sensor-specific) */
+ uint32_t skipFrames; /* frames to skip at start or modeswitch */
+ Pwl map; /* converts dioptres -> lens driver position */
+
+ CfgParams();
+ int read(const libcamera::YamlObject &params);
+ void initialise();
+ };
+
+ struct ScanRecord {
+ double focus;
+ double contrast;
+ double phase;
+ double conf;
+ };
+
+ void computeWeights();
+ bool getPhase(PdafData const &data, double &phase, double &conf) const;
+ double getContrast(struct bcm2835_isp_stats_focus const focus_stats[FOCUS_REGIONS]) const;
+ void doPDAF(double phase, double conf);
+ bool earlyTerminationByPhase(double phase);
+ double findPeak(unsigned index) const;
+ void doScan(double contrast, double phase, double conf);
+ void doAF(double contrast, double phase, double conf);
+ void updateLensPosition();
+ void startAF();
+ void startProgrammedScan();
+ void goIdle();
+
+ /* Configuration and settings */
+ CfgParams cfg_;
+ AfRange range_;
+ AfSpeed speed_;
+ AfMode mode_;
+ bool pauseFlag_;
+ libcamera::Rectangle statsRegion_;
+ std::vector<libcamera::Rectangle> windows_;
+ bool useWindows_;
+ uint8_t phaseWeights_[PDAF_DATA_ROWS][PDAF_DATA_COLS];
+ uint16_t contrastWeights_[FOCUS_REGIONS];
+ uint32_t sumWeights_;
+
+ /* Working state. */
+ ScanState scanState_;
+ bool initted_;
+ double ftarget_, fsmooth_;
+ double prevContrast_;
+ unsigned skipCount_, stepCount_, dropCount_;
+ unsigned scanMaxIndex_;
+ double scanMaxContrast_, scanMinContrast_;
+ std::vector<ScanRecord> scanData_;
+ AfState reportState_;
+};
+
+} // namespace RPiController