[RFC PATCH v5 28/32] lib/igt_color: add BT2020/BT709 transfer functions

[Harry Wentland]

BT.709 and BT.2020 transfer functions are identical, the
only difference beind that BT.2020 is defined with a higher
precision for 10 and 12 bpc encodings.

These transfer functions are defined as OETFs, not EOTFs,
so we create functions for them as OETF and its inverse.

Signed-off-by: Harry Wentland <harry.wentland at amd.com>
---
 lib/igt_color.c | 10 ++++++++++
 lib/igt_color.h |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/lib/igt_color.c b/lib/igt_color.c
index 0926385f4d82..ec8b27d1ef6f 100644
--- a/lib/igt_color.c
+++ b/lib/igt_color.c
@@ -107,6 +107,16 @@ void igt_color_srgb_inv_eotf(igt_pixel_t *pixel)
 	igt_color_inv_tf(pixel, &srgb_eotf);
 }
 
+void igt_color_bt2020_inv_oetf(igt_pixel_t *pixel)
+{
+	igt_color_tf(pixel, &bt2020_inv_oetf);
+}
+
+void igt_color_bt2020_oetf(igt_pixel_t *pixel)
+{
+	igt_color_inv_tf(pixel, &bt2020_inv_oetf);
+}
+
 void igt_color_pq_eotf(igt_pixel_t *pixel)
 {
 	tf_pq(pixel, &pq_eotf);
diff --git a/lib/igt_color.h b/lib/igt_color.h
index a97383fabaf3..813bd19ba439 100644
--- a/lib/igt_color.h
+++ b/lib/igt_color.h
@@ -25,6 +25,7 @@ struct igt_color_tf_pq {
 
 
 const struct igt_color_tf srgb_eotf = {2.4f, (float)(1/1.055), (float)(0.055/1.055), (float)(1/12.92), 0.04045f, 0, 0};
+const struct igt_color_tf bt2020_inv_oetf = {(float)(1/0.45f), (float)(1/1.0993f), (float)(0.0993f/1.0993f), (float)(1/4.5f), (float)(0.081), 0, 0};
 
 const struct igt_color_tf_pq pq_eotf = {-107/128.0f, 1.0f, 32/2523.0f, 2413/128.0f, -2392/128.0f, 8192/1305.0f };
 
@@ -117,6 +118,9 @@ void igt_color_pq_eotf(igt_pixel_t *pixel);
 void igt_color_pq_125_inv_eotf(igt_pixel_t *pixel);
 void igt_color_pq_125_eotf(igt_pixel_t *pixel);
 
+void igt_color_bt2020_inv_oetf(igt_pixel_t *pixel);
+void igt_color_bt2020_oetf(igt_pixel_t *pixel);
+
 void igt_color_ctm_3x4_50_desat(igt_pixel_t *pixel);
 void igt_color_ctm_3x4_overdrive(igt_pixel_t *pixel);
 void igt_color_ctm_3x4_oversaturate(igt_pixel_t *pixel);
-- 
2.44.0