Re-add linearised gamma LUT.

6 files changed, 27 insertions, 8 deletions

diff --git a/src/gamma_lut.cc b/src/gamma_lut.cc
index 4d61e60c..abe35b7c 100644
--- a/src/gamma_lut.cc
+++ b/src/gamma_lut.cc
@@ -25,13 +25,26 @@ using namespace dcp;
 
 LUTCache<GammaLUT> GammaLUT::cache;
 
-GammaLUT::GammaLUT (int bit_depth, float gamma)
+GammaLUT::GammaLUT (int bit_depth, float gamma, bool linearised)
 	: _bit_depth (bit_depth)
 	, _gamma (gamma)
+	, _linearised (linearised)
 {
 	_lut = new float[int(std::pow(2.0f, _bit_depth))];
 	int const bit_length = pow (2, _bit_depth);
-	for (int i = 0; i < bit_length; ++i) {
-		_lut[i] = pow(float(i) / (bit_length - 1), gamma);
+
+	if (_linearised) {
+		for (int i = 0; i < bit_length; ++i) {
+			float const p = static_cast<float> (i) / (bit_length - 1);
+			if (p > 0.04045) {
+				_lut[i] = pow ((p + 0.055) / 1.055, gamma);
+			} else {
+				_lut[i] = p / 12.92;
+			}
+		}
+	} else {
+		for (int i = 0; i < bit_length; ++i) {
+			_lut[i] = pow(float(i) / (bit_length - 1), gamma);
+		}
 	}
 }
diff --git a/src/gamma_lut.h b/src/gamma_lut.h
index 3fefdfd2..76a63ccf 100644
--- a/src/gamma_lut.h
+++ b/src/gamma_lut.h
@@ -27,7 +27,7 @@ namespace dcp {
 class GammaLUT
 {
 public:
-	GammaLUT (int bit_depth, float gamma);
+	GammaLUT (int bit_depth, float gamma, bool linearised);
 
 	~GammaLUT () {
 		delete[] _lut;
@@ -45,12 +45,17 @@ public:
 		return _gamma;
 	}
 
+	bool linearised () const {
+		return _linearised;
+	}
+
 	static LUTCache<GammaLUT> cache;
 	
 private:
 	float* _lut;
 	int _bit_depth;
 	float _gamma;
+	bool _linearised;
 };
 
 }
diff --git a/src/lut_cache.h b/src/lut_cache.h
index e2287775..5c75fe6a 100644
--- a/src/lut_cache.h
+++ b/src/lut_cache.h
@@ -28,7 +28,7 @@ template<class T>
 class LUTCache : public boost::noncopyable
 {
 public:
-	boost::shared_ptr<T> get (int bit_depth, float gamma)
+	boost::shared_ptr<T> get (int bit_depth, float gamma, bool linearised)
 	{
 		for (typename std::list<boost::shared_ptr<T> >::iterator i = _cache.begin(); i != _cache.end(); ++i) {
 			if ((*i)->bit_depth() == bit_depth && (*i)->gamma() == gamma) {
@@ -36,7 +36,7 @@ public:
 			}
 		}
 
-		boost::shared_ptr<T> lut (new T (bit_depth, gamma));
+		boost::shared_ptr<T> lut (new T (bit_depth, gamma, linearised));
 		_cache.push_back (lut);
 		return lut;
 	}
diff --git a/src/mono_picture_frame.cc b/src/mono_picture_frame.cc
index 6c2609ee..c2f8abb7 100644
--- a/src/mono_picture_frame.cc
+++ b/src/mono_picture_frame.cc
@@ -93,6 +93,6 @@ MonoPictureFrame::argb_frame (int reduce, float srgb_gamma) const
 {
 	return xyz_to_rgb (
 		decompress_j2k (const_cast<uint8_t*> (_buffer->RoData()), _buffer->Size(), reduce),
-		GammaLUT::cache.get (12, DCI_GAMMA), GammaLUT::cache.get (12, 1 / srgb_gamma)
+		GammaLUT::cache.get (12, DCI_GAMMA, false), GammaLUT::cache.get (12, 1 / srgb_gamma, false)
 		);
 }
diff --git a/src/stereo_picture_frame.cc b/src/stereo_picture_frame.cc
index 780ac362..0b56b216 100644
--- a/src/stereo_picture_frame.cc
+++ b/src/stereo_picture_frame.cc
@@ -84,7 +84,7 @@ StereoPictureFrame::argb_frame (Eye eye, int reduce, float srgb_gamma) const
 		break;
 	}
 	
-	return xyz_to_rgb (xyz_frame, GammaLUT::cache.get (12, DCI_GAMMA), GammaLUT::cache.get (12, 1 / srgb_gamma));
+	return xyz_to_rgb (xyz_frame, GammaLUT::cache.get (12, DCI_GAMMA, false), GammaLUT::cache.get (12, 1 / srgb_gamma, false));
 }
 
 uint8_t const *
diff --git a/src/wscript b/src/wscript
index 122c0abe..fd9f945b 100644
--- a/src/wscript
+++ b/src/wscript
@@ -94,6 +94,7 @@ def build(bld):
               stereo_picture_mxf.h
               stereo_picture_frame.h
               subtitle.h
+              subtitle_string.h
               types.h
               util.h
               version.h