[libcamera-devel] [PATCH v3 3/4] libcamera: ipa: raspberrypi: ALSC: Resample luminance table
Naushir Patuck
naush at raspberrypi.com
Tue Aug 4 10:49:17 CEST 2020
Hi David,
Thank you for the patch, LGTM.
On Sat, 1 Aug 2020 at 09:02, David Plowman
<david.plowman at raspberrypi.com> wrote:
>
> This fixes a bug where the luminance correction table was not being
> resampled according to the camera mode, in the same way as the colour
> tables. This could be noticeable if any camera modes crop
> aggressively.
>
> This resampling can be done "up front" in the SwitchMode, as we have
> only a single fixed luminance table. In order to protect the
> recalculation of the table from the asynchronous thread (which reads
> it) I've elected to wait for that thread to go idle (though I doubt it
> would have mattered much). As a by-product of stopping the thread, it
> no longer needs its own copy of the camera mode (async_camera_mode_).
>
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Reviewed-by: Naushir Patuck <naush at raspberrypi.com>
> ---
> src/ipa/raspberrypi/controller/rpi/alsc.cpp | 39 ++++++++++++++-------
> src/ipa/raspberrypi/controller/rpi/alsc.hpp | 3 +-
> 2 files changed, 28 insertions(+), 14 deletions(-)
>
> diff --git a/src/ipa/raspberrypi/controller/rpi/alsc.cpp b/src/ipa/raspberrypi/controller/rpi/alsc.cpp
> index 12359dc..4df9934 100644
> --- a/src/ipa/raspberrypi/controller/rpi/alsc.cpp
> +++ b/src/ipa/raspberrypi/controller/rpi/alsc.cpp
> @@ -173,19 +173,34 @@ void Alsc::Initialise()
> lambda_r_[i] = lambda_b_[i] = 1.0;
> }
>
> +void Alsc::waitForAysncThread()
> +{
> + if (async_started_) {
> + async_started_ = false;
> + std::unique_lock<std::mutex> lock(mutex_);
> + sync_signal_.wait(lock, [&] {
> + return async_finished_;
> + });
> + async_finished_ = false;
> + }
> +}
> +
> void Alsc::SwitchMode(CameraMode const &camera_mode, Metadata *metadata)
> {
> (void)metadata;
>
> + // Ensure the other thread isn't running while we do this.
> + waitForAysncThread();
> +
> // There's a bit of a question what we should do if the "crop" of the
> - // camera mode has changed. Any calculation currently in flight would
> - // not be useful to the new mode, so arguably we should abort it, and
> - // generate a new table (like the "first_time" code already here). When
> - // the crop doesn't change, we can presumably just leave things
> - // alone. For now, I think we'll just wait and see. When the crop does
> - // change, any effects should be transient, and if they're not transient
> - // enough, we'll revisit the question then.
> + // camera mode has changed. Should we effectively reset the algorithm
> + // and start over?
> camera_mode_ = camera_mode;
> +
> + // We must resample the luminance table like we do the others, but it's
> + // fixed so we can simply do it up front here.
> + resample_cal_table(config_.luminance_lut, camera_mode_, luminance_table_);
> +
> if (first_time_) {
> // On the first time, arrange for something sensible in the
> // initial tables. Construct the tables for some default colour
> @@ -201,7 +216,7 @@ void Alsc::SwitchMode(CameraMode const &camera_mode, Metadata *metadata)
> compensate_lambdas_for_cal(cal_table_b, lambda_b_,
> async_lambda_b_);
> add_luminance_to_tables(sync_results_, async_lambda_r_, 1.0,
> - async_lambda_b_, config_.luminance_lut,
> + async_lambda_b_, luminance_table_,
> config_.luminance_strength);
> memcpy(prev_sync_results_, sync_results_,
> sizeof(prev_sync_results_));
> @@ -266,8 +281,6 @@ void Alsc::restartAsync(StatisticsPtr &stats, Metadata *image_metadata)
> }
> copy_stats(statistics_, stats, alsc_status);
> frame_phase_ = 0;
> - // copy the camera mode so it won't change during the calculations
> - async_camera_mode_ = camera_mode_;
> async_started_ = true;
> {
> std::lock_guard<std::mutex> lock(mutex_);
> @@ -672,9 +685,9 @@ void Alsc::doAlsc()
> // Fetch the new calibrations (if any) for this CT. Resample them in
> // case the camera mode is not full-frame.
> get_cal_table(ct_, config_.calibrations_Cr, cal_table_tmp);
> - resample_cal_table(cal_table_tmp, async_camera_mode_, cal_table_r);
> + resample_cal_table(cal_table_tmp, camera_mode_, cal_table_r);
> get_cal_table(ct_, config_.calibrations_Cb, cal_table_tmp);
> - resample_cal_table(cal_table_tmp, async_camera_mode_, cal_table_b);
> + resample_cal_table(cal_table_tmp, camera_mode_, cal_table_b);
> // You could print out the cal tables for this image here, if you're
> // tuning the algorithm...
> (void)print_cal_table;
> @@ -697,7 +710,7 @@ void Alsc::doAlsc()
> compensate_lambdas_for_cal(cal_table_b, lambda_b_, async_lambda_b_);
> // Fold in the luminance table at the appropriate strength.
> add_luminance_to_tables(async_results_, async_lambda_r_, 1.0,
> - async_lambda_b_, config_.luminance_lut,
> + async_lambda_b_, luminance_table_,
> config_.luminance_strength);
> }
>
> diff --git a/src/ipa/raspberrypi/controller/rpi/alsc.hpp b/src/ipa/raspberrypi/controller/rpi/alsc.hpp
> index e895913..95572af 100644
> --- a/src/ipa/raspberrypi/controller/rpi/alsc.hpp
> +++ b/src/ipa/raspberrypi/controller/rpi/alsc.hpp
> @@ -60,10 +60,10 @@ private:
> AlscConfig config_;
> bool first_time_;
> CameraMode camera_mode_;
> + double luminance_table_[ALSC_CELLS_X * ALSC_CELLS_Y];
> std::thread async_thread_;
> void asyncFunc(); // asynchronous thread function
> std::mutex mutex_;
> - CameraMode async_camera_mode_;
> // condvar for async thread to wait on
> std::condition_variable async_signal_;
> // condvar for synchronous thread to wait on
> @@ -86,6 +86,7 @@ private:
> int frame_count2_;
> double sync_results_[3][ALSC_CELLS_Y][ALSC_CELLS_X];
> double prev_sync_results_[3][ALSC_CELLS_Y][ALSC_CELLS_X];
> + void waitForAysncThread();
> // The following are for the asynchronous thread to use, though the main
> // thread can set/reset them if the async thread is known to be idle:
> void restartAsync(StatisticsPtr &stats, Metadata *image_metadata);
> --
> 2.20.1
>
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