colorspace: Add support for gamma22 transfer characteristics

sekrit-twc · Sep 18, 2017 · 94bf39f · 94bf39f
1 parent 108f113
commit 94bf39f
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Showing 5 changed files with 20 additions and 2 deletions.
diff --git a/src/testapp/table.cpp b/src/testapp/table.cpp
@@ -76,13 +76,14 @@ const zimg::static_string_map<MatrixCoefficients, 10> g_matrix_table{
 	{ "ictcp",      MatrixCoefficients::REC_2100_ICTCP },
 };
 
-const zimg::static_string_map<TransferCharacteristics, 11> g_transfer_table{
+const zimg::static_string_map<TransferCharacteristics, 12> g_transfer_table{
 	{ "unspec",   TransferCharacteristics::UNSPECIFIED },
 	{ "linear",   TransferCharacteristics::LINEAR },
 	{ "log10",    TransferCharacteristics::LOG_10 },
 	{ "log316",   TransferCharacteristics::LOG_SQRT },
 	{ "240m",     TransferCharacteristics::SMPTE_240M },
 	{ "709",      TransferCharacteristics::REC_709 },
+	{ "470m",     TransferCharacteristics::REC_470_M },
 	{ "470bg",    TransferCharacteristics::REC_470_BG },
 	{ "xvycc",    TransferCharacteristics::XVYCC },
 	{ "srgb",     TransferCharacteristics::SRGB },

diff --git a/src/zimg/api/zimg.cpp b/src/zimg/api/zimg.cpp
@@ -250,11 +250,12 @@ zimg::colorspace::TransferCharacteristics translate_transfer(zimg_transfer_chara
 {
 	using zimg::colorspace::TransferCharacteristics;
 
-	static SM_CONSTEXPR_14 const zimg::static_map<zimg_transfer_characteristics_e, TransferCharacteristics, 14> map{
+	static SM_CONSTEXPR_14 const zimg::static_map<zimg_transfer_characteristics_e, TransferCharacteristics, 15> map{
 		{ ZIMG_TRANSFER_709,           TransferCharacteristics::REC_709 },
 		{ ZIMG_TRANSFER_UNSPECIFIED,   TransferCharacteristics::UNSPECIFIED },
 		{ ZIMG_TRANSFER_240M,          TransferCharacteristics::SMPTE_240M },
 		{ ZIMG_TRANSFER_601,           TransferCharacteristics::REC_709 },
+		{ ZIMG_TRANSFER_470M,          TransferCharacteristics::REC_470_M },
 		{ ZIMG_TRANSFER_470BG,         TransferCharacteristics::REC_470_BG },
 		{ ZIMG_TRANSFER_IEC_61966_2_4, TransferCharacteristics::XVYCC },
 		{ ZIMG_TRANSFER_IEC_61966_2_1, TransferCharacteristics::SRGB },

diff --git a/src/zimg/api/zimg.h b/src/zimg/api/zimg.h
@@ -280,6 +280,7 @@ typedef enum zimg_transfer_characteristics_e {
 	ZIMG_TRANSFER_INTERNAL      = -1, /**< Not part of the API. */
 	ZIMG_TRANSFER_709           = 1,
 	ZIMG_TRANSFER_UNSPECIFIED   = 2,
+	ZIMG_TRANSFER_470M          = 4,
 	ZIMG_TRANSFER_470BG         = 5,
 	ZIMG_TRANSFER_601           = 6,  /* Equivalent to 1. */
 	ZIMG_TRANSFER_240M          = 7,

diff --git a/src/zimg/colorspace/colorspace.h b/src/zimg/colorspace/colorspace.h
@@ -38,6 +38,7 @@ enum class TransferCharacteristics {
 	LOG_10,
 	LOG_SQRT,
 	REC_709,
+	REC_470_M,
 	REC_470_BG,
 	SMPTE_240M,
 	XVYCC,

diff --git a/src/zimg/colorspace/gamma.cpp b/src/zimg/colorspace/gamma.cpp
@@ -120,6 +120,16 @@ float rec_1886_inverse_eotf(float x) noexcept
 	return x < 0.0f ? 0.0f : zimg_x_powf(x, 1.0f / 2.4f);
 }
 
+float rec_470m_eotf(float x) noexcept
+{
+	return x < 0.0f ? 0.0f : zimg_x_powf(x, 2.2f);
+}
+
+float rec_470m_inverse_eotf(float x) noexcept
+{
+	return x < 0.0f ? 0.0f : zimg_x_powf(x, 1.0f / 2.2f);
+}
+
 float rec_470bg_eotf(float x) noexcept
 {
 	return x < 0.0f ? 0.0f : zimg_x_powf(x, 2.8f);
@@ -312,6 +322,10 @@ TransferFunction select_transfer_function(TransferCharacteristics transfer, doub
 		func.to_linear = scene_referred ? rec_709_inverse_oetf : rec_1886_eotf;
 		func.to_gamma = scene_referred ? rec_709_oetf : rec_1886_inverse_eotf;
 		break;
+	case TransferCharacteristics::REC_470_M:
+		func.to_linear = rec_470m_eotf;
+		func.to_gamma = rec_470m_inverse_eotf;
+		break;
 	case TransferCharacteristics::REC_470_BG:
 		func.to_linear = rec_470bg_eotf;
 		func.to_gamma = rec_470bg_inverse_eotf;