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Diffstat (limited to 'src/ipa/ipu3/algorithms/af.cpp')
| -rw-r--r-- | src/ipa/ipu3/algorithms/af.cpp | 458 |
1 files changed, 458 insertions, 0 deletions
diff --git a/src/ipa/ipu3/algorithms/af.cpp b/src/ipa/ipu3/algorithms/af.cpp new file mode 100644 index 00000000..cf68fb59 --- /dev/null +++ b/src/ipa/ipu3/algorithms/af.cpp @@ -0,0 +1,458 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2021, Red Hat + * + * IPU3 auto focus algorithm + */ + +#include "af.h" + +#include <algorithm> +#include <chrono> +#include <cmath> +#include <fcntl.h> +#include <sys/ioctl.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <unistd.h> + +#include <linux/videodev2.h> + +#include <libcamera/base/log.h> + +#include <libcamera/ipa/core_ipa_interface.h> + +/** + * \file af.h + */ + +/* + * Static variables from ChromiumOS Intel Camera HAL and ia_imaging library: + * - https://chromium.googlesource.com/chromiumos/platform/arc-camera/+/master/hal/intel/psl/ipu3/statsConverter/ipu3-stats.h + * - https://chromium.googlesource.com/chromiumos/platform/camera/+/refs/heads/main/hal/intel/ipu3/include/ia_imaging/af_public.h + */ + +/** The minimum horizontal grid dimension. */ +static constexpr uint8_t kAfMinGridWidth = 16; +/** The minimum vertical grid dimension. */ +static constexpr uint8_t kAfMinGridHeight = 16; +/** The maximum horizontal grid dimension. */ +static constexpr uint8_t kAfMaxGridWidth = 32; +/** The maximum vertical grid dimension. */ +static constexpr uint8_t kAfMaxGridHeight = 24; +/** The minimum value of Log2 of the width of the grid cell. */ +static constexpr uint16_t kAfMinGridBlockWidth = 4; +/** The minimum value of Log2 of the height of the grid cell. */ +static constexpr uint16_t kAfMinGridBlockHeight = 3; +/** The maximum value of Log2 of the width of the grid cell. */ +static constexpr uint16_t kAfMaxGridBlockWidth = 6; +/** The maximum value of Log2 of the height of the grid cell. */ +static constexpr uint16_t kAfMaxGridBlockHeight = 6; +/** The number of blocks in vertical axis per slice. */ +static constexpr uint16_t kAfDefaultHeightPerSlice = 2; + +namespace libcamera { + +using namespace std::literals::chrono_literals; + +namespace ipa::ipu3::algorithms { + +LOG_DEFINE_CATEGORY(IPU3Af) + +/** + * Maximum focus steps of the VCM control + * \todo should be obtained from the VCM driver + */ +static constexpr uint32_t kMaxFocusSteps = 1023; + +/* Minimum focus step for searching appropriate focus */ +static constexpr uint32_t kCoarseSearchStep = 30; +static constexpr uint32_t kFineSearchStep = 1; + +/* Max ratio of variance change, 0.0 < kMaxChange < 1.0 */ +static constexpr double kMaxChange = 0.5; + +/* The numbers of frame to be ignored, before performing focus scan. */ +static constexpr uint32_t kIgnoreFrame = 10; + +/* Fine scan range 0 < kFineRange < 1 */ +static constexpr double kFineRange = 0.05; + +/* Settings for IPU3 AF filter */ +static struct ipu3_uapi_af_filter_config afFilterConfigDefault = { + .y1_coeff_0 = { 0, 1, 3, 7 }, + .y1_coeff_1 = { 11, 13, 1, 2 }, + .y1_coeff_2 = { 8, 19, 34, 242 }, + .y1_sign_vec = 0x7fdffbfe, + .y2_coeff_0 = { 0, 1, 6, 6 }, + .y2_coeff_1 = { 13, 25, 3, 0 }, + .y2_coeff_2 = { 25, 3, 177, 254 }, + .y2_sign_vec = 0x4e53ca72, + .y_calc = { 8, 8, 8, 8 }, + .nf = { 0, 9, 0, 9, 0 }, +}; + +/** + * \class Af + * \brief An auto-focus algorithm based on IPU3 statistics + * + * This algorithm is used to determine the position of the lens to make a + * focused image. The IPU3 AF processing block computes the statistics that + * are composed by two types of filtered value and stores in a AF buffer. + * Typically, for a clear image, it has a relatively higher contrast than a + * blurred one. Therefore, if an image with the highest contrast can be + * found through the scan, the position of the len indicates to a clearest + * image. + */ +Af::Af() + : focus_(0), bestFocus_(0), currentVariance_(0.0), previousVariance_(0.0), + coarseCompleted_(false), fineCompleted_(false) +{ +} + +/** + * \brief Configure the Af given a configInfo + * \param[in] context The shared IPA context + * \param[in] configInfo The IPA configuration data + * \return 0 on success, a negative error code otherwise + */ +int Af::configure(IPAContext &context, const IPAConfigInfo &configInfo) +{ + struct ipu3_uapi_grid_config &grid = context.configuration.af.afGrid; + grid.width = kAfMinGridWidth; + grid.height = kAfMinGridHeight; + grid.block_width_log2 = kAfMinGridBlockWidth; + grid.block_height_log2 = kAfMinGridBlockHeight; + + /* + * \todo - while this clamping code is effectively a no-op, it satisfies + * the compiler that the constant definitions of the hardware limits + * are used, and paves the way to support dynamic grid sizing in the + * future. While the block_{width,height}_log2 remain assigned to the + * minimum, this code should be optimized out by the compiler. + */ + grid.width = std::clamp(grid.width, kAfMinGridWidth, kAfMaxGridWidth); + grid.height = std::clamp(grid.height, kAfMinGridHeight, kAfMaxGridHeight); + + grid.block_width_log2 = std::clamp(grid.block_width_log2, + kAfMinGridBlockWidth, + kAfMaxGridBlockWidth); + + grid.block_height_log2 = std::clamp(grid.block_height_log2, + kAfMinGridBlockHeight, + kAfMaxGridBlockHeight); + + grid.height_per_slice = kAfDefaultHeightPerSlice; + + /* Position the AF grid in the center of the BDS output. */ + Rectangle bds(configInfo.bdsOutputSize); + Size gridSize(grid.width << grid.block_width_log2, + grid.height << grid.block_height_log2); + + /* + * \todo - Support request metadata + * - Set the ROI based on any input controls in the request + * - Return the AF ROI as metadata in the Request + */ + Rectangle roi = gridSize.centeredTo(bds.center()); + Point start = roi.topLeft(); + + /* x_start and y_start should be even */ + grid.x_start = utils::alignDown(start.x, 2); + grid.y_start = utils::alignDown(start.y, 2); + grid.y_start |= IPU3_UAPI_GRID_Y_START_EN; + + /* Initial max focus step */ + maxStep_ = kMaxFocusSteps; + + /* Initial frame ignore counter */ + afIgnoreFrameReset(); + + /* Initial focus value */ + context.activeState.af.focus = 0; + /* Maximum variance of the AF statistics */ + context.activeState.af.maxVariance = 0; + /* The stable AF value flag. if it is true, the AF should be in a stable state. */ + context.activeState.af.stable = false; + + return 0; +} + +/** + * \copydoc libcamera::ipa::Algorithm::prepare + */ +void Af::prepare(IPAContext &context, + [[maybe_unused]] const uint32_t frame, + [[maybe_unused]] IPAFrameContext &frameContext, + ipu3_uapi_params *params) +{ + const struct ipu3_uapi_grid_config &grid = context.configuration.af.afGrid; + params->acc_param.af.grid_cfg = grid; + params->acc_param.af.filter_config = afFilterConfigDefault; + + /* Enable AF processing block */ + params->use.acc_af = 1; +} + +/** + * \brief AF coarse scan + * \param[in] context The shared IPA context + * + * Find a near focused image using a coarse step. The step is determined by + * kCoarseSearchStep. + */ +void Af::afCoarseScan(IPAContext &context) +{ + if (coarseCompleted_) + return; + + if (afNeedIgnoreFrame()) + return; + + if (afScan(context, kCoarseSearchStep)) { + coarseCompleted_ = true; + context.activeState.af.maxVariance = 0; + focus_ = context.activeState.af.focus - + (context.activeState.af.focus * kFineRange); + context.activeState.af.focus = focus_; + previousVariance_ = 0; + maxStep_ = std::clamp(focus_ + static_cast<uint32_t>((focus_ * kFineRange)), + 0U, kMaxFocusSteps); + } +} + +/** + * \brief AF fine scan + * \param[in] context The shared IPA context + * + * Find an optimum lens position with moving 1 step for each search. + */ +void Af::afFineScan(IPAContext &context) +{ + if (!coarseCompleted_) + return; + + if (afNeedIgnoreFrame()) + return; + + if (afScan(context, kFineSearchStep)) { + context.activeState.af.stable = true; + fineCompleted_ = true; + } +} + +/** + * \brief AF reset + * \param[in] context The shared IPA context + * + * Reset all the parameters to start over the AF process. + */ +void Af::afReset(IPAContext &context) +{ + if (afNeedIgnoreFrame()) + return; + + context.activeState.af.maxVariance = 0; + context.activeState.af.focus = 0; + focus_ = 0; + context.activeState.af.stable = false; + ignoreCounter_ = kIgnoreFrame; + previousVariance_ = 0.0; + coarseCompleted_ = false; + fineCompleted_ = false; + maxStep_ = kMaxFocusSteps; +} + +/** + * \brief AF variance comparison + * \param[in] context The IPA context + * \param[in] min_step The VCM movement step + * + * We always pick the largest variance to replace the previous one. The image + * with a larger variance also indicates it is a clearer image than previous + * one. If we find a negative derivative, we return immediately. + * + * \return True, if it finds a AF value. + */ +bool Af::afScan(IPAContext &context, int min_step) +{ + if (focus_ > maxStep_) { + /* If reach the max step, move lens to the position. */ + context.activeState.af.focus = bestFocus_; + return true; + } else { + /* + * Find the maximum of the variance by estimating its + * derivative. If the direction changes, it means we have + * passed a maximum one step before. + */ + if ((currentVariance_ - context.activeState.af.maxVariance) >= + -(context.activeState.af.maxVariance * 0.1)) { + /* + * Positive and zero derivative: + * The variance is still increasing. The focus could be + * increased for the next comparison. Also, the max variance + * and previous focus value are updated. + */ + bestFocus_ = focus_; + focus_ += min_step; + context.activeState.af.focus = focus_; + context.activeState.af.maxVariance = currentVariance_; + } else { + /* + * Negative derivative: + * The variance starts to decrease which means the maximum + * variance is found. Set focus step to previous good one + * then return immediately. + */ + context.activeState.af.focus = bestFocus_; + return true; + } + } + + previousVariance_ = currentVariance_; + LOG(IPU3Af, Debug) << " Previous step is " + << bestFocus_ + << " Current step is " + << focus_; + return false; +} + +/** + * \brief Determine the frame to be ignored + * \return Return True if the frame should be ignored, false otherwise + */ +bool Af::afNeedIgnoreFrame() +{ + if (ignoreCounter_ == 0) + return false; + else + ignoreCounter_--; + return true; +} + +/** + * \brief Reset frame ignore counter + */ +void Af::afIgnoreFrameReset() +{ + ignoreCounter_ = kIgnoreFrame; +} + +/** + * \brief Estimate variance + * \param[in] y_items The AF filter data set from the IPU3 statistics buffer + * \param[in] isY1 Selects between filter Y1 or Y2 to calculate the variance + * + * Calculate the mean of the data set provided by \a y_item, and then calculate + * the variance of that data set from the mean. + * + * The operation can work on one of two sets of values contained within the + * y_item data set supplied by the IPU3. The two data sets are the results of + * both the Y1 and Y2 filters which are used to support coarse (Y1) and fine + * (Y2) calculations of the contrast. + * + * \return The variance of the values in the data set \a y_item selected by \a isY1 + */ +double Af::afEstimateVariance(Span<const y_table_item_t> y_items, bool isY1) +{ + uint32_t total = 0; + double mean; + double var_sum = 0; + + for (auto y : y_items) + total += isY1 ? y.y1_avg : y.y2_avg; + + mean = total / y_items.size(); + + for (auto y : y_items) { + double avg = isY1 ? y.y1_avg : y.y2_avg; + var_sum += pow(avg - mean, 2); + } + + return var_sum / y_items.size(); +} + +/** + * \brief Determine out-of-focus situation + * \param[in] context The IPA context + * + * Out-of-focus means that the variance change rate for a focused and a new + * variance is greater than a threshold. + * + * \return True if the variance threshold is crossed indicating lost focus, + * false otherwise + */ +bool Af::afIsOutOfFocus(IPAContext &context) +{ + const uint32_t diff_var = std::abs(currentVariance_ - + context.activeState.af.maxVariance); + const double var_ratio = diff_var / context.activeState.af.maxVariance; + + LOG(IPU3Af, Debug) << "Variance change rate: " + << var_ratio + << " Current VCM step: " + << context.activeState.af.focus; + + if (var_ratio > kMaxChange) + return true; + else + return false; +} + +/** + * \brief Determine the max contrast image and lens position + * \param[in] context The IPA context + * \param[in] frame The frame context sequence number + * \param[in] frameContext The current frame context + * \param[in] stats The statistics buffer of IPU3 + * \param[out] metadata Metadata for the frame, to be filled by the algorithm + * + * Ideally, a clear image also has a relatively higher contrast. So, every + * image for each focus step should be tested to find an optimal focus step. + * + * The Hill Climbing Algorithm[1] is used to find the maximum variance of the + * AF statistics which is the AF output of IPU3. The focus step is increased + * then the variance of the AF statistics are estimated. If it finds the + * negative derivative we have just passed the peak, and we infer that the best + * focus is found. + * + * [1] Hill Climbing Algorithm, https://en.wikipedia.org/wiki/Hill_climbing + */ +void Af::process(IPAContext &context, [[maybe_unused]] const uint32_t frame, + [[maybe_unused]] IPAFrameContext &frameContext, + const ipu3_uapi_stats_3a *stats, + [[maybe_unused]] ControlList &metadata) +{ + /* Evaluate the AF buffer length */ + uint32_t afRawBufferLen = context.configuration.af.afGrid.width * + context.configuration.af.afGrid.height; + + ASSERT(afRawBufferLen < IPU3_UAPI_AF_Y_TABLE_MAX_SIZE); + + Span<const y_table_item_t> y_items(reinterpret_cast<const y_table_item_t *>(&stats->af_raw_buffer.y_table), + afRawBufferLen); + + /* + * Calculate the mean and the variance of AF statistics for a given grid. + * For coarse: y1 are used. + * For fine: y2 results are used. + */ + currentVariance_ = afEstimateVariance(y_items, !coarseCompleted_); + + if (!context.activeState.af.stable) { + afCoarseScan(context); + afFineScan(context); + } else { + if (afIsOutOfFocus(context)) + afReset(context); + else + afIgnoreFrameReset(); + } +} + +REGISTER_IPA_ALGORITHM(Af, "Af") + +} /* namespace ipa::ipu3::algorithms */ + +} /* namespace libcamera */ |