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libcamera: ipa: raspberrypi: ALSC: Improve behaviour when camera mode changes

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Now that we stop the asynchronous thread on a SwitchMode, we would do
better to regenerate all the tables if the new camera mode crops in a
significantly different way to the old one. A few minor tweaks make
sense along with this:

* Reset the lambda values when we reset everything. It wouldn't make
  sense to re-start with the old mode's values.

* Use the last recorded colour temperature to generate new tables rather
  than any default value.

* Set the frame "phase" counter to ensure the adaptive procedure will
  run asap.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
This commit is contained in:
David Plowman 2020-08-01 09:01:51 +01:00 • committed by Laurent Pinchart
parent 7f6b9121cc
commit 79a834f24c
1 changed files with 37 additions and 17 deletions
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54
src/ipa/raspberrypi/controller/rpi/alsc.cpp
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@ -166,11 +166,8 @@ void Alsc::Initialise()
RPI_LOG("Alsc");
frame_count2_ = frame_count_ = frame_phase_ = 0;
first_time_ = true;
// Initialise the lambdas. Each call to Process then restarts from the
// previous results. Also initialise the previous frame tables to the
// same harmless values.
for (int i = 0; i < XY; i++)
lambda_r_[i] = lambda_b_[i] = 1.0;
ct_ = config_.default_ct;
// The lambdas are initialised in the SwitchMode.
}
void Alsc::waitForAysncThread()
@ -185,31 +182,53 @@ void Alsc::waitForAysncThread()
}
}
static bool compare_modes(CameraMode const &cm0, CameraMode const &cm1)
{
// Return true if the modes crop from the sensor significantly differently.
int left_diff = abs(cm0.crop_x - cm1.crop_x);
int top_diff = abs(cm0.crop_y - cm1.crop_y);
int right_diff = fabs(cm0.crop_x + cm0.scale_x * cm0.width -
cm1.crop_x - cm1.scale_x * cm1.width);
int bottom_diff = fabs(cm0.crop_y + cm0.scale_y * cm0.height -
cm1.crop_y - cm1.scale_y * cm1.height);
// These thresholds are a rather arbitrary amount chosen to trigger
// when carrying on with the previously calculated tables might be
// worse than regenerating them (but without the adaptive algorithm).
int threshold_x = cm0.sensor_width >> 4;
int threshold_y = cm0.sensor_height >> 4;
return left_diff > threshold_x || right_diff > threshold_x ||
top_diff > threshold_y || bottom_diff > threshold_y;
}
void Alsc::SwitchMode(CameraMode const &camera_mode, Metadata *metadata)
{
(void)metadata;
// We're going to start over with the tables if there's any "significant"
// change.
bool reset_tables = first_time_ || compare_modes(camera_mode_, camera_mode);
// 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. 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
// temperature. This echoes the code in doAlsc, without the
// adaptive algorithm.
if (reset_tables) {
// Upon every "table reset", arrange for something sensible to be
// generated. Construct the tables for the previous recorded colour
// temperature. In order to start over from scratch we initialise
// the lambdas, but the rest of this code then echoes the code in
// doAlsc, without the adaptive algorithm.
for (int i = 0; i < XY; i++)
lambda_r_[i] = lambda_b_[i] = 1.0;
double cal_table_r[XY], cal_table_b[XY], cal_table_tmp[XY];
get_cal_table(4000, config_.calibrations_Cr, cal_table_tmp);
get_cal_table(ct_, config_.calibrations_Cr, cal_table_tmp);
resample_cal_table(cal_table_tmp, camera_mode_, cal_table_r);
get_cal_table(4000, config_.calibrations_Cb, cal_table_tmp);
get_cal_table(ct_, config_.calibrations_Cb, cal_table_tmp);
resample_cal_table(cal_table_tmp, camera_mode_, cal_table_b);
compensate_lambdas_for_cal(cal_table_r, lambda_r_,
async_lambda_r_);
@ -220,6 +239,7 @@ void Alsc::SwitchMode(CameraMode const &camera_mode, Metadata *metadata)
config_.luminance_strength);
memcpy(prev_sync_results_, sync_results_,
sizeof(prev_sync_results_));
frame_phase_ = config_.frame_period; // run the algo again asap
first_time_ = false;
}
}
@ -265,8 +285,8 @@ void Alsc::restartAsync(StatisticsPtr &stats, Metadata *image_metadata)
{
RPI_LOG("Starting ALSC thread");
// Get the current colour temperature. It's all we need from the
// metadata.
ct_ = get_ct(image_metadata, config_.default_ct);
// metadata. Default to the last CT value (which could be the default).
ct_ = get_ct(image_metadata, ct_);
// We have to copy the statistics here, dividing out our best guess of
// the LSC table that the pipeline applied to them.
AlscStatus alsc_status;