[PATCH 2/6] ipa: ipu3: Use centralised libipa helpers

[Daniel Scally]

Use the centralised libipa helpers instead of open coding common
functions.

Signed-off-by: Daniel Scally <dan.scally at ideasonboard.com>
---
 src/ipa/ipu3/algorithms/agc.cpp |  7 ++++---
 src/ipa/ipu3/algorithms/awb.cpp | 34 +++------------------------------
 src/ipa/ipu3/algorithms/awb.h   |  1 -
 3 files changed, 7 insertions(+), 35 deletions(-)

diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp
index c5f3d8f0..3eb73ef0 100644
--- a/src/ipa/ipu3/algorithms/agc.cpp
+++ b/src/ipa/ipu3/algorithms/agc.cpp
@@ -17,6 +17,7 @@
 
 #include <libcamera/ipa/core_ipa_interface.h>
 
+#include "libipa/helpers.h"
 #include "libipa/histogram.h"
 
 /**
@@ -185,9 +186,9 @@ double Agc::estimateLuminance(double gain) const
 		blueSum += std::min(std::get<2>(rgbTriples_[i]) * gain, 255.0);
 	}
 
-	double ySum = redSum * rGain_ * 0.299
-		    + greenSum * gGain_ * 0.587
-		    + blueSum * bGain_ * 0.114;
+	double ySum = ipa::rec601LuminanceFromRGB(redSum * rGain_,
+						  greenSum * gGain_,
+						  blueSum * bGain_);
 
 	return ySum / (bdsGrid_.height * bdsGrid_.width) / 255;
 }
diff --git a/src/ipa/ipu3/algorithms/awb.cpp b/src/ipa/ipu3/algorithms/awb.cpp
index 4d6e3994..0085edf4 100644
--- a/src/ipa/ipu3/algorithms/awb.cpp
+++ b/src/ipa/ipu3/algorithms/awb.cpp
@@ -13,6 +13,8 @@
 
 #include <libcamera/control_ids.h>
 
+#include "libipa/helpers.h"
+
 /**
  * \file awb.h
  */
@@ -301,36 +303,6 @@ void Awb::prepare(IPAContext &context,
 	params->use.acc_ccm = 1;
 }
 
-/**
- * The function estimates the correlated color temperature using
- * from RGB color space input.
- * In physics and color science, the Planckian locus or black body locus is
- * the path or locus that the color of an incandescent black body would take
- * in a particular chromaticity space as the blackbody temperature changes.
- *
- * If a narrow range of color temperatures is considered (those encapsulating
- * daylight being the most practical case) one can approximate the Planckian
- * locus in order to calculate the CCT in terms of chromaticity coordinates.
- *
- * More detailed information can be found in:
- * https://en.wikipedia.org/wiki/Color_temperature#Approximation
- */
-uint32_t Awb::estimateCCT(double red, double green, double blue)
-{
-	/* Convert the RGB values to CIE tristimulus values (XYZ) */
-	double X = (-0.14282) * (red) + (1.54924) * (green) + (-0.95641) * (blue);
-	double Y = (-0.32466) * (red) + (1.57837) * (green) + (-0.73191) * (blue);
-	double Z = (-0.68202) * (red) + (0.77073) * (green) + (0.56332) * (blue);
-
-	/* Calculate the normalized chromaticity values */
-	double x = X / (X + Y + Z);
-	double y = Y / (X + Y + Z);
-
-	/* Calculate CCT */
-	double n = (x - 0.3320) / (0.1858 - y);
-	return 449 * n * n * n + 3525 * n * n + 6823.3 * n + 5520.33;
-}
-
 /* Generate an RGB vector with the average values for each zone */
 void Awb::generateZones()
 {
@@ -437,7 +409,7 @@ void Awb::awbGreyWorld()
 	       blueGain = sumBlue.G / (sumBlue.B + 1);
 
 	/* Color temperature is not relevant in Grey world but still useful to estimate it :-) */
-	asyncResults_.temperatureK = estimateCCT(sumRed.R, sumRed.G, sumBlue.B);
+	asyncResults_.temperatureK = ipa::estimateCCT(sumRed.R, sumRed.G, sumBlue.B);
 
 	/*
 	 * Gain values are unsigned integer value ranging [0, 8) with 13 bit
diff --git a/src/ipa/ipu3/algorithms/awb.h b/src/ipa/ipu3/algorithms/awb.h
index c0202823..a13c49ac 100644
--- a/src/ipa/ipu3/algorithms/awb.h
+++ b/src/ipa/ipu3/algorithms/awb.h
@@ -75,7 +75,6 @@ private:
 	void generateAwbStats(const ipu3_uapi_stats_3a *stats);
 	void clearAwbStats();
 	void awbGreyWorld();
-	uint32_t estimateCCT(double red, double green, double blue);
 	static constexpr uint16_t threshold(float value);
 	static constexpr uint16_t gainValue(double gain);
 
-- 
2.30.2