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-rw-r--r--src/ipa/rkisp1/algorithms/awb.cpp22
1 files changed, 15 insertions, 7 deletions
diff --git a/src/ipa/rkisp1/algorithms/awb.cpp b/src/ipa/rkisp1/algorithms/awb.cpp
index 59664d09..a3066fbb 100644
--- a/src/ipa/rkisp1/algorithms/awb.cpp
+++ b/src/ipa/rkisp1/algorithms/awb.cpp
@@ -265,21 +265,29 @@ void Awb::process(IPAContext &context,
frameContext.awb.temperatureK = estimateCCT(redMean, greenMean, blueMean);
- /* Estimate the red and blue gains to apply in a grey world. */
+ /*
+ * Estimate the red and blue gains to apply in a grey world. The green
+ * gain is hardcoded to 1.0.
+ */
double redGain = greenMean / (redMean + 1);
double blueGain = greenMean / (blueMean + 1);
+ /*
+ * Clamp the gain values to the hardware, which expresses gains as Q2.8
+ * unsigned integer values. Set the minimum just above zero to avoid
+ * divisions by zero when computing the raw means in subsequent
+ * iterations.
+ */
+ redGain = std::clamp(redGain, 1.0 / 256, 1023.0 / 256);
+ blueGain = std::clamp(blueGain, 1.0 / 256, 1023.0 / 256);
+
/* Filter the values to avoid oscillations. */
double speed = 0.2;
redGain = speed * redGain + (1 - speed) * activeState.awb.gains.automatic.red;
blueGain = speed * blueGain + (1 - speed) * activeState.awb.gains.automatic.blue;
- /*
- * Gain values are unsigned integer value, range 0 to 4 with 8 bit
- * fractional part. Hardcode the green gain to 1.0.
- */
- activeState.awb.gains.automatic.red = std::clamp(redGain, 0.0, 1023.0 / 256);
- activeState.awb.gains.automatic.blue = std::clamp(blueGain, 0.0, 1023.0 / 256);
+ activeState.awb.gains.automatic.red = redGain;
+ activeState.awb.gains.automatic.blue = blueGain;
activeState.awb.gains.automatic.green = 1.0;
LOG(RkISP1Awb, Debug) << std::showpoint