@@ -235,6 +235,8 @@ void Agc::Prepare(Metadata *image_metadata)
int lock_count = lock_count_;
lock_count_ = 0;
status_.digital_gain = 1.0;
+ fetchAwbStatus(image_metadata); // always fetch it so that Process knows it's been done
+
if (status_.total_exposure_value) {
// Process has run, so we have meaningful values.
DeviceStatus device_status;
@@ -300,7 +302,7 @@ void Agc::Process(StatisticsPtr &stats, Metadata *image_metadata)
// Some of the exposure has to be applied as digital gain, so work out
// what that is. This function also tells us whether it's decided to
// "desaturate" the image more quickly.
- bool desaturate = applyDigitalGain(image_metadata, gain, target_Y);
+ bool desaturate = applyDigitalGain(gain, target_Y);
// The results have to be filtered so as not to change too rapidly.
filterExposure(desaturate);
// The last thing is to divide up the exposure value into a shutter time
@@ -377,14 +379,19 @@ void Agc::fetchCurrentExposure(Metadata *image_metadata)
current_.total_exposure_no_dg = current_.shutter * current_.analogue_gain;
}
-static double compute_initial_Y(bcm2835_isp_stats *stats, Metadata *image_metadata,
+void Agc::fetchAwbStatus(Metadata *image_metadata)
+{
+ awb_.gain_r = 1.0; // in case not found in metadata
+ awb_.gain_g = 1.0;
+ awb_.gain_b = 1.0;
+ if (image_metadata->Get("awb.status", awb_) != 0)
+ LOG(RPiAgc, Warning) << "Agc: no AWB status found";
+}
+
+static double compute_initial_Y(bcm2835_isp_stats *stats, AwbStatus const &awb,
double weights[])
{
bcm2835_isp_stats_region *regions = stats->agc_stats;
- struct AwbStatus awb;
- awb.gain_r = awb.gain_g = awb.gain_b = 1.0; // in case no metadata
- if (image_metadata->Get("awb.status", awb) != 0)
- LOG(RPiAgc, Warning) << "Agc: no AWB status found";
// Note how the calculation below means that equal weights give you
// "average" metering (i.e. all pixels equally important).
double R_sum = 0, G_sum = 0, B_sum = 0, pixel_sum = 0;
@@ -436,7 +443,7 @@ void Agc::computeGain(bcm2835_isp_stats *statistics, Metadata *image_metadata,
target_Y =
config_.Y_target.Eval(config_.Y_target.Domain().Clip(lux.lux));
target_Y = std::min(EV_GAIN_Y_TARGET_LIMIT, target_Y * ev_gain);
- double initial_Y = compute_initial_Y(statistics, image_metadata,
+ double initial_Y = compute_initial_Y(statistics, awb_,
metering_mode_->weights);
gain = std::min(10.0, target_Y / (initial_Y + .001));
LOG(RPiAgc, Debug) << "Initially Y " << initial_Y << " target " << target_Y
@@ -482,19 +489,13 @@ void Agc::computeTargetExposure(double gain)
LOG(RPiAgc, Debug) << "Target total_exposure " << target_.total_exposure;
}
-bool Agc::applyDigitalGain(Metadata *image_metadata, double gain,
- double target_Y)
+bool Agc::applyDigitalGain(double gain, double target_Y)
{
- double dg = 1.0;
+ double min_colour_gain = std::min({ awb_.gain_r, awb_.gain_g, awb_.gain_b, 1.0 });
+ ASSERT(min_colour_gain != 0.0);
+ double dg = 1.0 / min_colour_gain;
// I think this pipeline subtracts black level and rescales before we
// get the stats, so no need to worry about it.
- struct AwbStatus awb;
- if (image_metadata->Get("awb.status", awb) == 0) {
- double min_gain = std::min(awb.gain_r,
- std::min(awb.gain_g, awb.gain_b));
- dg *= std::max(1.0, 1.0 / min_gain);
- } else
- LOG(RPiAgc, Warning) << "Agc: no AWB status found";
LOG(RPiAgc, Debug) << "after AWB, target dg " << dg << " gain " << gain
<< " target_Y " << target_Y;
// Finally, if we're trying to reduce exposure but the target_Y is
@@ -83,11 +83,11 @@ private:
AgcConfig config_;
void housekeepConfig();
void fetchCurrentExposure(Metadata *image_metadata);
+ void fetchAwbStatus(Metadata *image_metadata);
void computeGain(bcm2835_isp_stats *statistics, Metadata *image_metadata,
double &gain, double &target_Y);
void computeTargetExposure(double gain);
- bool applyDigitalGain(Metadata *image_metadata, double gain,
- double target_Y);
+ bool applyDigitalGain(double gain, double target_Y);
void filterExposure(bool desaturate);
void divideUpExposure();
void writeAndFinish(Metadata *image_metadata, bool desaturate);
@@ -95,6 +95,7 @@ private:
AgcExposureMode *exposure_mode_;
AgcConstraintMode *constraint_mode_;
uint64_t frame_count_;
+ AwbStatus awb_;
struct ExposureValues {
ExposureValues() : shutter(0), analogue_gain(0),
total_exposure(0), total_exposure_no_dg(0) {}