Use two LUTs.inaccurate-gamma

12 files changed, 46 insertions, 40 deletions

diff --git a/src/gamma_transfer_function.cc b/src/gamma_transfer_function.cc
index 1875221e..33513b78 100644
--- a/src/gamma_transfer_function.cc
+++ b/src/gamma_transfer_function.cc
@@ -55,13 +55,14 @@ GammaTransferFunction::GammaTransferFunction (double gamma)
 
 
 double *
-GammaTransferFunction::make_lut (int bit_depth, bool inverse) const
+GammaTransferFunction::make_lut (double from, double to, int bit_depth, bool inverse) const
 {
 	int const bit_length = int(std::pow(2.0f, bit_depth));
 	auto lut = new double[bit_length];
 	double const gamma = inverse ? (1 / _gamma) : _gamma;
 	for (int i = 0; i < bit_length; ++i) {
-		lut[i] = pow(double(i) / (bit_length - 1), gamma);
+		double const x = double(i) / (bit_length - 1);
+		lut[i] = pow((x * (to - from)) + from, gamma);
 	}
 
 	return lut;
diff --git a/src/gamma_transfer_function.h b/src/gamma_transfer_function.h
index 8402d6af..947fec66 100644
--- a/src/gamma_transfer_function.h
+++ b/src/gamma_transfer_function.h
@@ -58,7 +58,7 @@ public:
 	bool about_equal (std::shared_ptr<const TransferFunction> other, double epsilon) const override;
 
 protected:
-	double * make_lut (int bit_depth, bool inverse) const override;
+	double * make_lut (double from, double to, int bit_depth, bool inverse) const override;
 
 private:
 	double _gamma;
diff --git a/src/identity_transfer_function.cc b/src/identity_transfer_function.cc
index c01e6698..bd754c77 100644
--- a/src/identity_transfer_function.cc
+++ b/src/identity_transfer_function.cc
@@ -47,8 +47,9 @@ using std::dynamic_pointer_cast;
 using namespace dcp;
 
 
+/* XXX */
 double *
-IdentityTransferFunction::make_lut (int bit_depth, bool) const
+IdentityTransferFunction::make_lut (double, double, int bit_depth, bool) const
 {
 	int const bit_length = int(std::pow(2.0f, bit_depth));
 	auto lut = new double[bit_length];
diff --git a/src/identity_transfer_function.h b/src/identity_transfer_function.h
index de7a897a..918f6185 100644
--- a/src/identity_transfer_function.h
+++ b/src/identity_transfer_function.h
@@ -49,7 +49,7 @@ public:
 	bool about_equal (std::shared_ptr<const TransferFunction> other, double epsilon) const override;
 
 protected:
-	double * make_lut (int bit_depth, bool inverse) const override;
+	double * make_lut (double from, double to, int bit_depth, bool inverse) const override;
 };
 
 
diff --git a/src/modified_gamma_transfer_function.cc b/src/modified_gamma_transfer_function.cc
index 039e9284..e9b09a6d 100644
--- a/src/modified_gamma_transfer_function.cc
+++ b/src/modified_gamma_transfer_function.cc
@@ -57,8 +57,9 @@ ModifiedGammaTransferFunction::ModifiedGammaTransferFunction (double power, doub
 }
 
 
+/* XXX */
 double *
-ModifiedGammaTransferFunction::make_lut (int bit_depth, bool inverse) const
+ModifiedGammaTransferFunction::make_lut (double, double, int bit_depth, bool inverse) const
 {
 	int const bit_length = int(std::pow(2.0f, bit_depth));
 	double* lut = new double[bit_length];
diff --git a/src/modified_gamma_transfer_function.h b/src/modified_gamma_transfer_function.h
index 34904855..abc51e35 100644
--- a/src/modified_gamma_transfer_function.h
+++ b/src/modified_gamma_transfer_function.h
@@ -77,7 +77,7 @@ public:
 	bool about_equal (std::shared_ptr<const TransferFunction>, double epsilon) const override;
 
 protected:
-	double * make_lut (int bit_depth, bool inverse) const override;
+	double * make_lut (double from, double to, int bit_depth, bool inverse) const override;
 
 private:
 	double _power;
diff --git a/src/rgb_xyz.cc b/src/rgb_xyz.cc
index f2aaec8e..47b7a9ee 100644
--- a/src/rgb_xyz.cc
+++ b/src/rgb_xyz.cc
@@ -80,8 +80,8 @@ dcp::xyz_to_rgba (
 	int* xyz_y = xyz_image->data (1);
 	int* xyz_z = xyz_image->data (2);
 
-	double const * lut_in = conversion.out()->lut (12, false);
-	double const * lut_out = conversion.in()->lut (16, true);
+	double const * lut_in = conversion.out()->lut("all", 0, 1, 12, false);
+	double const * lut_out = conversion.in()->lut("all", 0, 1, 16, true);
 	boost::numeric::ublas::matrix<double> const matrix = conversion.xyz_to_rgb ();
 
 	double fast_matrix[9] = {
@@ -157,8 +157,8 @@ dcp::xyz_to_rgb (
 	int* xyz_y = xyz_image->data (1);
 	int* xyz_z = xyz_image->data (2);
 
-	double const * lut_in = conversion.out()->lut (12, false);
-	double const * lut_out = conversion.in()->lut (16, true);
+	double const * lut_in = conversion.out()->lut("all", 0, 1, 12, false);
+	double const * lut_out = conversion.in()->lut("all", 0, 1, 16, true);
 	auto const matrix = conversion.xyz_to_rgb ();
 
 	double fast_matrix[9] = {
@@ -237,23 +237,23 @@ dcp::combined_rgb_to_xyz (ColourConversion const & conversion, double* matrix)
 	auto const bradford = conversion.bradford ();
 
 	matrix[0] = (bradford (0, 0) * rgb_to_xyz (0, 0) + bradford (0, 1) * rgb_to_xyz (1, 0) + bradford (0, 2) * rgb_to_xyz (2, 0))
-		* DCI_COEFFICIENT * 1048576;
+		* DCI_COEFFICIENT;
 	matrix[1] = (bradford (0, 0) * rgb_to_xyz (0, 1) + bradford (0, 1) * rgb_to_xyz (1, 1) + bradford (0, 2) * rgb_to_xyz (2, 1))
-		* DCI_COEFFICIENT * 1048576;
+		* DCI_COEFFICIENT;
 	matrix[2] = (bradford (0, 0) * rgb_to_xyz (0, 2) + bradford (0, 1) * rgb_to_xyz (1, 2) + bradford (0, 2) * rgb_to_xyz (2, 2))
-		* DCI_COEFFICIENT * 1048576;
+		* DCI_COEFFICIENT;
 	matrix[3] = (bradford (1, 0) * rgb_to_xyz (0, 0) + bradford (1, 1) * rgb_to_xyz (1, 0) + bradford (1, 2) * rgb_to_xyz (2, 0))
-		* DCI_COEFFICIENT * 1048576;
+		* DCI_COEFFICIENT;
 	matrix[4] = (bradford (1, 0) * rgb_to_xyz (0, 1) + bradford (1, 1) * rgb_to_xyz (1, 1) + bradford (1, 2) * rgb_to_xyz (2, 1))
-		* DCI_COEFFICIENT * 1048576;
+		* DCI_COEFFICIENT;
 	matrix[5] = (bradford (1, 0) * rgb_to_xyz (0, 2) + bradford (1, 1) * rgb_to_xyz (1, 2) + bradford (1, 2) * rgb_to_xyz (2, 2))
-		* DCI_COEFFICIENT * 1048576;
+		* DCI_COEFFICIENT;
 	matrix[6] = (bradford (2, 0) * rgb_to_xyz (0, 0) + bradford (2, 1) * rgb_to_xyz (1, 0) + bradford (2, 2) * rgb_to_xyz (2, 0))
-		* DCI_COEFFICIENT * 1048576;
+		* DCI_COEFFICIENT;
 	matrix[7] = (bradford (2, 0) * rgb_to_xyz (0, 1) + bradford (2, 1) * rgb_to_xyz (1, 1) + bradford (2, 2) * rgb_to_xyz (2, 1))
-		* DCI_COEFFICIENT * 1048576;
+		* DCI_COEFFICIENT;
 	matrix[8] = (bradford (2, 0) * rgb_to_xyz (0, 2) + bradford (2, 1) * rgb_to_xyz (1, 2) + bradford (2, 2) * rgb_to_xyz (2, 2))
-		* DCI_COEFFICIENT * 1048576;
+		* DCI_COEFFICIENT;
 }
 
 
@@ -276,8 +276,10 @@ dcp::rgb_to_xyz (
 		double x, y, z;
 	} d;
 
-	auto const * lut_in = conversion.in()->lut (12, false);
-	auto const * lut_out = conversion.out()->lut (20, true);
+	auto const * lut_in = conversion.in()->lut ("all", 0, 1, 12, false);
+	auto constexpr piece = 0.02;
+	auto const * lut_out_low = conversion.out()->lut("low_inv", 0, piece, 16, true);
+	auto const * lut_out_high = conversion.out()->lut("high_inv", piece, 1, 12, true);
 
 	/* This is is the product of the RGB to XYZ matrix, the Bradford transform and the DCI companding */
 	double fast_matrix[9];
@@ -303,21 +305,21 @@ dcp::rgb_to_xyz (
 
 			/* Clamp */
 
-			if (d.x < 0 || d.y < 0 || d.z < 0 || d.x > 1048576 || d.y > 1048576 || d.z > 1048576) {
+			if (d.x < 0 || d.y < 0 || d.z < 0 || d.x > 1 || d.y > 1 || d.z > 1) {
 				++clamped;
 			}
 
 			d.x = max (0.0, d.x);
 			d.y = max (0.0, d.y);
 			d.z = max (0.0, d.z);
-			d.x = min (1048576.0, d.x);
-			d.y = min (1048576.0, d.y);
-			d.z = min (1048576.0, d.z);
+			d.x = min (1.0, d.x);
+			d.y = min (1.0, d.y);
+			d.z = min (1.0, d.z);
 
 			/* Out gamma LUT */
-			*xyz_x++ = lrint (lut_out[lrint(d.x)] * 4095);
-			*xyz_y++ = lrint (lut_out[lrint(d.y)] * 4095);
-			*xyz_z++ = lrint (lut_out[lrint(d.z)] * 4095);
+			*xyz_x++ = lrint((d.x < piece ? lut_out_low[lrint((d.x / piece) * 65536)] : lut_out_high[lrint(((d.x - piece) / (1 - piece)) * 4096)]) * 4095);
+			*xyz_y++ = lrint((d.y < piece ? lut_out_low[lrint((d.y / piece) * 65536)] : lut_out_high[lrint(((d.y - piece) / (1 - piece)) * 4096)]) * 4095);
+			*xyz_z++ = lrint((d.z < piece ? lut_out_low[lrint((d.z / piece) * 65536)] : lut_out_high[lrint(((d.z - piece) / (1 - piece)) * 4096)]) * 4095);
 		}
 	}
 
diff --git a/src/s_gamut3_transfer_function.cc b/src/s_gamut3_transfer_function.cc
index edfbe2ad..c234b002 100644
--- a/src/s_gamut3_transfer_function.cc
+++ b/src/s_gamut3_transfer_function.cc
@@ -47,8 +47,9 @@ using std::dynamic_pointer_cast;
 using namespace dcp;
 
 
+/* XXX */
 double *
-SGamut3TransferFunction::make_lut (int bit_depth, bool inverse) const
+SGamut3TransferFunction::make_lut (double, double, int bit_depth, bool inverse) const
 {
 	int const bit_length = int(std::pow(2.0f, bit_depth));
 	double* lut = new double[bit_length];
diff --git a/src/s_gamut3_transfer_function.h b/src/s_gamut3_transfer_function.h
index 0d297e8b..4c3714b9 100644
--- a/src/s_gamut3_transfer_function.h
+++ b/src/s_gamut3_transfer_function.h
@@ -49,7 +49,7 @@ public:
 	bool about_equal (std::shared_ptr<const TransferFunction> other, double epsilon) const override;
 
 protected:
-	double * make_lut (int bit_depth, bool inverse) const override;
+	double * make_lut (double from, double to, int bit_depth, bool inverse) const override;
 };
 
 
diff --git a/src/transfer_function.cc b/src/transfer_function.cc
index 00968e2f..237f6844 100644
--- a/src/transfer_function.cc
+++ b/src/transfer_function.cc
@@ -62,15 +62,15 @@ TransferFunction::~TransferFunction ()
 
 
 double const *
-TransferFunction::lut (int bit_depth, bool inverse) const
+TransferFunction::lut (std::string name, double from, double to, int bit_depth, bool inverse) const
 {
 	boost::mutex::scoped_lock lm (_mutex);
 
-	auto i = _luts.find (make_pair (bit_depth, inverse));
+	auto i = _luts.find (name);
 	if (i != _luts.end ()) {
 		return i->second;
 	}
 
-	_luts[make_pair(bit_depth, inverse)] = make_lut (bit_depth, inverse);
-	return _luts[make_pair(bit_depth, inverse)];
+	_luts[name] = make_lut (from, to, bit_depth, inverse);
+	return _luts[name];
 }
diff --git a/src/transfer_function.h b/src/transfer_function.h
index a52011ec..5b591901 100644
--- a/src/transfer_function.h
+++ b/src/transfer_function.h
@@ -63,16 +63,16 @@ public:
 	virtual ~TransferFunction ();
 
 	/** @return A look-up table (of size 2^bit_depth) whose values range from 0 to 1 */
-	double const * lut (int bit_depth, bool inverse) const;
+	double const * lut (std::string name, double from, double to, int bit_depth, bool inverse) const;
 
 	virtual bool about_equal (std::shared_ptr<const TransferFunction> other, double epsilon) const = 0;
 
 protected:
 	/** Make a LUT and return an array allocated by new */
-	virtual double * make_lut (int bit_depth, bool inverse) const = 0;
+	virtual double * make_lut (double from, double to, int bit_depth, bool inverse) const = 0;
 
 private:
-	mutable std::map<std::pair<int, bool>, double*> _luts;
+	mutable std::map<std::string, double*> _luts;
 	/** mutex to protect _luts */
 	mutable boost::mutex _mutex;
 };
diff --git a/test/colour_conversion_test.cc b/test/colour_conversion_test.cc
index 5a6bdd85..04c182a3 100644
--- a/test/colour_conversion_test.cc
+++ b/test/colour_conversion_test.cc
@@ -44,7 +44,7 @@ using namespace dcp;
 static void
 check_gamma (shared_ptr<const TransferFunction> tf, int bit_depth, bool inverse, float gamma)
 {
-	double const * lut = tf->lut (bit_depth, inverse);
+	double const * lut = tf->lut ("all", 0, 1, bit_depth, inverse);
 	int const count = rint (pow (2.0, bit_depth));
 
 	for (int i = 0; i < count; ++i) {
@@ -55,7 +55,7 @@ check_gamma (shared_ptr<const TransferFunction> tf, int bit_depth, bool inverse,
 static void
 check_modified_gamma (shared_ptr<const TransferFunction> tf, int bit_depth, bool inverse, double power, double threshold, double A, double B)
 {
-	double const * lut = tf->lut (bit_depth, inverse);
+	double const * lut = tf->lut ("all", 0, 1, bit_depth, inverse);
 	int const count = rint (pow (2.0, bit_depth));
 
 	for (int i = 0; i < count; ++i) {