Change output gamma correction to be closer to EasyDCP behaviour.

6 files changed, 10 insertions, 48 deletions

diff --git a/src/picture_frame.cc b/src/picture_frame.cc
index 98802101..7e6bc1f8 100644
--- a/src/picture_frame.cc
+++ b/src/picture_frame.cc
@@ -26,7 +26,6 @@
 #include "lut.h"
 #include "util.h"
 #include "gamma_lut.h"
-#include "xyz_srgb_lut.h"
 
 #define DCI_GAMMA 2.6
 
@@ -84,7 +83,7 @@ MonoPictureFrame::argb_frame (int reduce, float srgb_gamma) const
 {
 	opj_image_t* xyz_frame = decompress_j2k (const_cast<uint8_t*> (_buffer->RoData()), _buffer->Size(), reduce);
 	assert (xyz_frame->numcomps == 3);
-	shared_ptr<ARGBFrame> f = xyz_to_rgb (xyz_frame, GammaLUT::cache.get (12, DCI_GAMMA), XYZsRGBLUT::cache.get (12, srgb_gamma));
+	shared_ptr<ARGBFrame> f = xyz_to_rgb (xyz_frame, GammaLUT::cache.get (12, DCI_GAMMA), GammaLUT::cache.get (12, 1 / srgb_gamma));
 	opj_image_destroy (xyz_frame);
 	return f;
 }
@@ -139,7 +138,7 @@ StereoPictureFrame::argb_frame (Eye eye, int reduce, float srgb_gamma) const
 	}
 	
 	assert (xyz_frame->numcomps == 3);
-	shared_ptr<ARGBFrame> f = xyz_to_rgb (xyz_frame, GammaLUT::cache.get (12, DCI_GAMMA), XYZsRGBLUT::cache.get (12, srgb_gamma));
+	shared_ptr<ARGBFrame> f = xyz_to_rgb (xyz_frame, GammaLUT::cache.get (12, DCI_GAMMA), GammaLUT::cache.get (12, 1 / srgb_gamma));
 	opj_image_destroy (xyz_frame);
 	return f;
 }
diff --git a/src/util.cc b/src/util.cc
index 2fae8561..c66e63f5 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -35,7 +35,6 @@
 #include "types.h"
 #include "argb_frame.h"
 #include "gamma_lut.h"
-#include "xyz_srgb_lut.h"
 
 using std::string;
 using std::stringstream;
@@ -203,11 +202,13 @@ libdcp::decompress_j2k (uint8_t* data, int64_t size, int reduce)
  *  @return RGB image.
  */
 shared_ptr<ARGBFrame>
-libdcp::xyz_to_rgb (opj_image_t* xyz_frame, shared_ptr<const GammaLUT> lut_in, shared_ptr<const XYZsRGBLUT> lut_out)
+libdcp::xyz_to_rgb (opj_image_t* xyz_frame, shared_ptr<const GammaLUT> lut_in, shared_ptr<const GammaLUT> lut_out)
 {
 	float const dci_coefficient = 48.0 / 52.37;
 
-        /* sRGB color matrix for XYZ -> RGB */
+        /* sRGB color matrix for XYZ -> RGB.  This is the same as the one used by the Fraunhofer
+	   EasyDCP player, I think.
+	*/
 
 	float const colour_matrix[3][3] = {
 		{  3.24096989631653,   -1.5373831987381,  -0.498610764741898 },
@@ -264,9 +265,9 @@ libdcp::xyz_to_rgb (opj_image_t* xyz_frame, shared_ptr<const GammaLUT> lut_in, s
 			d.b = max (d.b, 0.0);
 			
 			/* Out gamma LUT */
-			*argb_line++ = lut_out->lut()[(int) (d.b * max_colour)];
-			*argb_line++ = lut_out->lut()[(int) (d.g * max_colour)];
-			*argb_line++ = lut_out->lut()[(int) (d.r * max_colour)];
+			*argb_line++ = lut_out->lut()[(int) (d.b * max_colour)] * 0xff;
+			*argb_line++ = lut_out->lut()[(int) (d.g * max_colour)] * 0xff;
+			*argb_line++ = lut_out->lut()[(int) (d.r * max_colour)] * 0xff;
 			*argb_line++ = 0xff;
 		}
 		
diff --git a/src/util.h b/src/util.h
index 2036a7ce..6332ddc0 100644
--- a/src/util.h
+++ b/src/util.h
@@ -60,7 +60,7 @@ extern std::string content_kind_to_string (ContentKind kind);
 extern ContentKind content_kind_from_string (std::string kind);
 extern bool empty_or_white_space (std::string s);
 extern opj_image_t* decompress_j2k (uint8_t* data, int64_t size, int reduce);
-extern boost::shared_ptr<ARGBFrame> xyz_to_rgb (opj_image_t* xyz_frame, boost::shared_ptr<const GammaLUT>, boost::shared_ptr<const XYZsRGBLUT>);
+extern boost::shared_ptr<ARGBFrame> xyz_to_rgb (opj_image_t* xyz_frame, boost::shared_ptr<const GammaLUT>, boost::shared_ptr<const GammaLUT>);
 
 }
 
diff --git a/src/wscript b/src/wscript
index efba2502..3960f2b0 100644
--- a/src/wscript
+++ b/src/wscript
@@ -31,7 +31,6 @@ def build(bld):
                  util.cc
                  version.cc
                  xml.cc
-                 xyz_srgb_lut.cc
                  """
 
     headers = """
diff --git a/src/xyz_srgb_lut.cc b/src/xyz_srgb_lut.cc
deleted file mode 100644
index 3d207195..00000000
--- a/src/xyz_srgb_lut.cc
+++ /dev/null
@@ -1,24 +0,0 @@
-#include <iostream>
-#include <cmath>
-#include "xyz_srgb_lut.h"
-
-using namespace libdcp;
-
-LUTCache<XYZsRGBLUT> XYZsRGBLUT::cache;
-
-XYZsRGBLUT::XYZsRGBLUT(int bits, float gamma)
-	: LUT<int> (bits, gamma)
-{
-	int const bit_length = pow(2, bits);
-
-	for (int i = 0; i < bit_length; ++i) {
-		float v = float(i) / (bit_length - 1);
-		if (v < (0.04045 / 12.92)) {
-			v *= 12.92;
-		} else {
-			v = (1.055 * pow (v, (1 / gamma))) - 0.055;
-		}
-
-		_lut[i] = int(v * 255);
-	}
-}
diff --git a/src/xyz_srgb_lut.h b/src/xyz_srgb_lut.h
deleted file mode 100644
index 63f89178..00000000
--- a/src/xyz_srgb_lut.h
+++ /dev/null
@@ -1,13 +0,0 @@
-#include "lut.h"
-#include "lut_cache.h"
-
-namespace libdcp {
-
-class XYZsRGBLUT : public LUT<int>
-{
-public:
-	XYZsRGBLUT(int colour_depth, float gamma);
-	static LUTCache<XYZsRGBLUT> cache;
-};
-
-}