[Improvement]Fix loss of permissibleRatio calcaulation accuracy.
The previous method performs exponential calculation after natural logarithm and subtraction operation, which brings loss of calculation accuracy. So it is recommended to modify this method from the perspective of scientific calculation.
Change-Id: Id6c7ca3c222226d642bd075519da693a8538dba6
Signed-off-by: linkai <linkai@xiaomi.com>
diff --git a/services/core/java/com/android/server/display/BrightnessMappingStrategy.java b/services/core/java/com/android/server/display/BrightnessMappingStrategy.java
index 6f12155..6a407e9 100644
--- a/services/core/java/com/android/server/display/BrightnessMappingStrategy.java
+++ b/services/core/java/com/android/server/display/BrightnessMappingStrategy.java
@@ -440,9 +440,8 @@
}
private float permissibleRatio(float currLux, float prevLux) {
- return MathUtils.exp(MAX_GRAD
- * (MathUtils.log(currLux + LUX_GRAD_SMOOTHING)
- - MathUtils.log(prevLux + LUX_GRAD_SMOOTHING)));
+ return MathUtils.pow((currLux + LUX_GRAD_SMOOTHING)
+ / (prevLux + LUX_GRAD_SMOOTHING), MAX_GRAD);
}
protected float inferAutoBrightnessAdjustment(float maxGamma, float desiredBrightness,