lib: Add igt_color_encoding

Add some helpers for generating rgb<->ycbcr conversion matrices.

v2: Add enums for color_encoding/color_range
    Fix full range handling (lacked +-0.5<->+-1.0 scaling)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 147 insertions, 0 deletions

diff --git a/lib/igt_color_encoding.c b/lib/igt_color_encoding.c
new file mode 100644
index 00000000..b1648a74
--- /dev/null
+++ b/lib/igt_color_encoding.c
@@ -0,0 +1,147 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "igt_color_encoding.h"
+#include "igt_matrix.h"
+
+struct color_encoding {
+	float kr, kb;
+};
+
+static const struct color_encoding color_encodings[IGT_NUM_COLOR_ENCODINGS] = {
+	[IGT_COLOR_YCBCR_BT601] = { .kr = .299f, .kb = .114f, },
+	[IGT_COLOR_YCBCR_BT709] = { .kr = .2126f, .kb = .0722f, },
+	[IGT_COLOR_YCBCR_BT2020] = { .kr = .2627f, .kb = .0593f, },
+};
+
+static struct igt_mat4 rgb_to_ycbcr_matrix(const struct color_encoding *e)
+{
+	float kr, kg, kb;
+
+	kr = e->kr;
+	kb = e->kb;
+	kg = 1.0f - kr - kb;
+
+	struct igt_mat4 ret = {
+		.d[0 * 4 + 0] = kr,
+		.d[1 * 4 + 0] = kg,
+		.d[2 * 4 + 0] = kb,
+
+		.d[0 * 4 + 1] = -kr / (1.0f - kb),
+		.d[1 * 4 + 1] = -kg / (1.0f - kb),
+		.d[2 * 4 + 1] = 1.0f,
+
+		.d[0 * 4 + 2] = 1.0f,
+		.d[1 * 4 + 2] = -kg / (1.0f - kr),
+		.d[2 * 4 + 2] = -kb / (1.0f - kr),
+
+		.d[3 * 4 + 3] = 1.0f,
+	};
+
+	return ret;
+}
+
+static struct igt_mat4 ycbcr_to_rgb_matrix(const struct color_encoding *e)
+{
+	float kr, kg, kb;
+
+	kr = e->kr;
+	kb = e->kb;
+	kg = 1.0f - kr - kb;
+
+	struct igt_mat4 ret = {
+		.d[0 * 4 + 0] = 1.0f,
+		.d[1 * 4 + 0] = 0.0f,
+		.d[2 * 4 + 0] = 1.0 - kr,
+
+		.d[0 * 4 + 1] = 1.0f,
+		.d[1 * 4 + 1] = -(1.0 - kb) * kb / kg,
+		.d[2 * 4 + 1] = -(1.0 - kr) * kr / kg,
+
+		.d[0 * 4 + 2] = 1.0f,
+		.d[1 * 4 + 2] = 1.0 - kb,
+		.d[2 * 4 + 2] = 0.0f,
+
+		.d[3 * 4 + 3] = 1.0f,
+	};
+
+	return ret;
+}
+
+static struct igt_mat4 ycbcr_input_convert_matrix(enum igt_color_range color_range)
+{
+	struct igt_mat4 t, s;
+
+	if (color_range == IGT_COLOR_YCBCR_FULL_RANGE) {
+		t = igt_matrix_translate(0.0f, -128.0f, -128.0f);
+		s = igt_matrix_scale(1.0f, 2.0f, 2.0f);
+	} else {
+		t = igt_matrix_translate(-16.0f, -128.0f, -128.0f);
+		s = igt_matrix_scale(255.0f / (235.0f - 16.0f),
+				     255.0f / (240.0f - 128.0f),
+				     255.0f / (240.0f - 128.0f));
+	}
+
+	return igt_matrix_multiply(&s, &t);
+}
+
+static struct igt_mat4 ycbcr_output_convert_matrix(enum igt_color_range color_range)
+{
+	struct igt_mat4 s, t;
+
+	if (color_range == IGT_COLOR_YCBCR_FULL_RANGE) {
+		s = igt_matrix_scale(1.0f, 0.5f, 0.5f);
+		t = igt_matrix_translate(0.0f, 128.0f, 128.0f);
+	} else {
+		s = igt_matrix_scale((235.0f - 16.0f) / 255.0f,
+				     (240.0f - 128.0f) / 255.0f,
+				     (240.0f - 128.0f) / 255.0f);
+		t = igt_matrix_translate(16.0f, 128.0f, 128.0f);
+	}
+
+	return igt_matrix_multiply(&t, &s);
+}
+
+struct igt_mat4 igt_ycbcr_to_rgb_matrix(enum igt_color_encoding color_encoding,
+					enum igt_color_range color_range)
+{
+	const struct color_encoding *e = &color_encodings[color_encoding];
+	struct igt_mat4 r, c;
+
+	r = ycbcr_input_convert_matrix(color_range);
+	c = ycbcr_to_rgb_matrix(e);
+
+	return igt_matrix_multiply(&c, &r);
+}
+
+struct igt_mat4 igt_rgb_to_ycbcr_matrix(enum igt_color_encoding color_encoding,
+					enum igt_color_range color_range)
+{
+	const struct color_encoding *e = &color_encodings[color_encoding];
+	struct igt_mat4 c, r;
+
+	c = rgb_to_ycbcr_matrix(e);
+	r = ycbcr_output_convert_matrix(color_range);
+
+	return igt_matrix_multiply(&r, &c);
+}