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ipa: ipu3: agc: Compute the gain for each frame

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Now that we have the real exposure applied at each frame, remove the
early return based on a frame counter and compute the gain for each
frame.

Introduce a number of startup frames during which the filter speed is
1.0, meaning we apply instantly the exposure value calculated and not a
slower filtered one. This is used to have a faster convergence, and
those frames may be dropped in a future development to hide the
convergance process from the viewer.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
This commit is contained in:
Jean-Michel Hautbois 2021-11-04 14:20:42 +01:00
parent 5614c95794
commit 4fdf1e4f5e
2 changed files with 11 additions and 16 deletions
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26
src/ipa/ipu3/algorithms/agc.cpp
View file

@ -45,11 +45,6 @@ namespace ipa::ipu3::algorithms {
LOG_DEFINE_CATEGORY(IPU3Agc)
/* Number of frames to wait before calculating stats on minimum exposure */
static constexpr uint32_t kInitialFrameMinAECount = 4;
/* Number of frames to wait between new gain/shutter time estimations */
static constexpr uint32_t kFrameSkipCount = 6;
/* Limits for analogue gain values */
static constexpr double kMinAnalogueGain = 1.0;
static constexpr double kMaxAnalogueGain = 8.0;
@ -69,10 +64,13 @@ static constexpr double kEvGainTarget = 0.5;
*/
static constexpr uint32_t kMinCellsPerZoneRatio = 255 * 20 / 100;
/* Number of frames to wait before calculating stats on minimum exposure */
static constexpr uint32_t kNumStartupFrames = 10;
Agc::Agc()
: frameCount_(0), lastFrame_(0), iqMean_(0.0), lineDuration_(0s),
minExposureLines_(0), maxExposureLines_(0), filteredExposure_(0s),
currentExposure_(0s), prevExposureValue_(0s)
: frameCount_(0), iqMean_(0.0), lineDuration_(0s), minExposureLines_(0),
maxExposureLines_(0), filteredExposure_(0s), currentExposure_(0s),
prevExposureValue_(0s)
{
}
@ -159,6 +157,11 @@ void Agc::measureBrightness(const ipu3_uapi_stats_3a *stats,
void Agc::filterExposure()
{
double speed = 0.2;
/* Adapt instantly if we are in startup phase */
if (frameCount_ < kNumStartupFrames)
speed = 1.0;
if (filteredExposure_ == 0s) {
/* DG stands for digital gain.*/
filteredExposure_ = currentExposure_;
@ -185,13 +188,6 @@ void Agc::filterExposure()
*/
void Agc::computeExposure(IPAFrameContext &frameContext)
{
/* Algorithm initialization should wait for first valid frames */
/* \todo - have a number of frames given by DelayedControls ?
* - implement a function for IIR */
if ((frameCount_ < kInitialFrameMinAECount) || (frameCount_ - lastFrame_ < kFrameSkipCount))
return;
lastFrame_ = frameCount_;
/* Are we correctly exposed ? */
if (std::abs(iqMean_ - kEvGainTarget * knumHistogramBins) <= 1) {

1
src/ipa/ipu3/algorithms/agc.h
View file

@ -37,7 +37,6 @@ private:
void computeExposure(IPAFrameContext &frameContext);
uint64_t frameCount_;
uint64_t lastFrame_;
double iqMean_;