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-rw-r--r--src/ipa/raspberrypi/controller/rpi/agc.cpp25
1 files changed, 15 insertions, 10 deletions
diff --git a/src/ipa/raspberrypi/controller/rpi/agc.cpp b/src/ipa/raspberrypi/controller/rpi/agc.cpp
index 9a5d84f7..f0c70a0a 100644
--- a/src/ipa/raspberrypi/controller/rpi/agc.cpp
+++ b/src/ipa/raspberrypi/controller/rpi/agc.cpp
@@ -385,18 +385,23 @@ static double compute_initial_Y(bcm2835_isp_stats *stats, Metadata *image_metada
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";
- double Y_sum = 0, weight_sum = 0;
+ // 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;
for (int i = 0; i < AGC_STATS_SIZE; i++) {
- if (regions[i].counted == 0)
- continue;
- weight_sum += weights[i];
- double Y = regions[i].r_sum * awb.gain_r * .299 +
- regions[i].g_sum * awb.gain_g * .587 +
- regions[i].b_sum * awb.gain_b * .114;
- Y /= regions[i].counted;
- Y_sum += Y * weights[i];
+ R_sum += regions[i].r_sum * weights[i];
+ G_sum += regions[i].g_sum * weights[i];
+ B_sum += regions[i].b_sum * weights[i];
+ pixel_sum += regions[i].counted * weights[i];
}
- return Y_sum / weight_sum / (1 << PIPELINE_BITS);
+ if (pixel_sum == 0.0) {
+ LOG(RPiAgc, Warning) << "compute_initial_Y: pixel_sum is zero";
+ return 0;
+ }
+ double Y_sum = R_sum * awb.gain_r * .299 +
+ G_sum * awb.gain_g * .587 +
+ B_sum * awb.gain_b * .114;
+ return Y_sum / pixel_sum / (1 << PIPELINE_BITS);
}
// We handle extra gain through EV by adjusting our Y targets. However, you