[PATCH v5 24/37] lib/igt_color: Add PQ variants for 0-1 and 0-125 range

[Harry Wentland]

Add PQ SW transforms. The most obvious to do the PQ EOTF
is to transform [0.0, 1.0] non-linear values to [0.0, 1.0]
linear values, and same in the inverse. So we add transforms
that do this.

Some HW (like AMD's) has scaling baked into the PQ EOTF
and will scale [0.0, 1.0] non-linear values to [0.0, 125.0]
linear values when applying the PQ EOTF. The inverse will
take [0.0, 125.0] linear values and output [0.0, 1.0]
linear values. We're adding a transform that can handle
this variant as well.

Signed-off-by: Harry Wentland <harry.wentland at amd.com>
---
 lib/igt_color.c | 81 +++++++++++++++++++++++++++++++++++++++++++------
 lib/igt_color.h | 13 ++++++++
 2 files changed, 84 insertions(+), 10 deletions(-)

diff --git a/lib/igt_color.c b/lib/igt_color.c
index 43179a17e41b..0926385f4d82 100644
--- a/lib/igt_color.c
+++ b/lib/igt_color.c
@@ -20,6 +20,13 @@ static float clamp(float val, float min, float max)
 	return ((val < min) ? min : ((val > max) ? max : val));
 }
 
+static void igt_color_multiply(igt_pixel_t *pixel, float multiplier)
+{
+	pixel->r *= multiplier;
+	pixel->g *= multiplier;
+	pixel->b *= multiplier;
+}
+
 static float igt_color_tf_eval_unclamped(const struct igt_color_tf *fn, float x)
 {
 	if (x < fn->d)
@@ -51,24 +58,78 @@ static void tf_inverse(const struct igt_color_tf *fn, struct igt_color_tf *inv)
 	}
 }
 
-void igt_color_srgb_inv_eotf(igt_pixel_t *pixel)
+static float pq_eval(const struct igt_color_tf_pq *pq, float x)
+{
+	return powf(fmaxf(pq->A + pq->B * powf(x, pq->C), 0)
+		       / (pq->D + pq->E * powf(x, pq->C)),
+			    pq->F);
+}
+
+static void pq_inv(struct igt_color_tf_pq *inv)
+{
+	inv->A = -pq_eotf.A;
+	inv->B = pq_eotf.D;
+	inv->C = 1.0f / pq_eotf.F;
+	inv->D = pq_eotf.B;
+	inv->E = -pq_eotf.E;
+	inv->F = 1.0f / pq_eotf.C;
+}
+
+static void igt_color_tf(igt_pixel_t *pixel, const struct igt_color_tf *tf)
+{
+	pixel->r = igt_color_tf_eval(tf, pixel->r);
+	pixel->g = igt_color_tf_eval(tf, pixel->g);
+	pixel->b = igt_color_tf_eval(tf, pixel->b);
+}
+
+static void igt_color_inv_tf(igt_pixel_t *pixel, const struct igt_color_tf *tf)
 {
 	struct igt_color_tf inv;
 
-	tf_inverse(&srgb_eotf, &inv);
-
-	pixel->r = igt_color_tf_eval(&inv, pixel->r);
-	pixel->g = igt_color_tf_eval(&inv, pixel->g);
-	pixel->b = igt_color_tf_eval(&inv, pixel->b);
+	tf_inverse(tf, &inv);
+	igt_color_tf(pixel, &inv);
 }
 
-
+static void tf_pq(igt_pixel_t *pixel, const struct igt_color_tf_pq *pq)
+{
+	pixel->r = pq_eval(pq, pixel->r);
+	pixel->g = pq_eval(pq, pixel->g);
+	pixel->b = pq_eval(pq, pixel->b);
+}
 
 void igt_color_srgb_eotf(igt_pixel_t *pixel)
 {
-	pixel->r = igt_color_tf_eval(&srgb_eotf, pixel->r);
-	pixel->g = igt_color_tf_eval(&srgb_eotf, pixel->g);
-	pixel->b = igt_color_tf_eval(&srgb_eotf, pixel->b);
+	igt_color_tf(pixel, &srgb_eotf);
+}
+
+void igt_color_srgb_inv_eotf(igt_pixel_t *pixel)
+{
+	igt_color_inv_tf(pixel, &srgb_eotf);
+}
+
+void igt_color_pq_eotf(igt_pixel_t *pixel)
+{
+	tf_pq(pixel, &pq_eotf);
+}
+
+void igt_color_pq_inv_eotf(igt_pixel_t *pixel)
+{
+	struct igt_color_tf_pq inv;
+
+	pq_inv(&inv);
+	tf_pq(pixel, &inv);
+}
+
+void igt_color_pq_125_eotf(igt_pixel_t *pixel)
+{
+	igt_color_pq_eotf(pixel);
+	igt_color_multiply(pixel, 125.0f);
+}
+
+void igt_color_pq_125_inv_eotf(igt_pixel_t *pixel)
+{
+	igt_color_multiply(pixel, 1/125.0f);
+	igt_color_pq_inv_eotf(pixel);
 }
 
 static void igt_color_apply_3x4_ctm(igt_pixel_t *pixel, const igt_matrix_3x4_t *matrix)
diff --git a/lib/igt_color.h b/lib/igt_color.h
index d218550f6dd0..a97383fabaf3 100644
--- a/lib/igt_color.h
+++ b/lib/igt_color.h
@@ -19,8 +19,15 @@ struct igt_color_tf {
     float g, a,b,c,d,e,f;
 };
 
+struct igt_color_tf_pq {
+	float A, B, C, D, E, F, G;
+};
+
+
 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_pq pq_eotf = {-107/128.0f, 1.0f, 32/2523.0f, 2413/128.0f, -2392/128.0f, 8192/1305.0f };
+
 typedef struct igt_pixel {
 	float r;
 	float g;
@@ -104,6 +111,12 @@ void igt_colorop_set_ctm_3x4(igt_display_t *display,
 void igt_color_srgb_inv_eotf(igt_pixel_t *pixel);
 void igt_color_srgb_eotf(igt_pixel_t *pixel);
 
+void igt_color_pq_inv_eotf(igt_pixel_t *pixel);
+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_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);
-- 
2.46.0