From: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
To: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-arm-kernel@lists.infradead.org
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <maxime.ripard@bootlin.com>,
Sean Paul <sean@poorly.run>, David Airlie <airlied@linux.ie>,
Chen-Yu Tsai <wens@csie.org>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
linux-sunxi@googlegroups.com, Daniel Vetter <daniel@ffwll.ch>,
Paul Kocialkowski <contact@paulk.fr>
Subject: [PATCH v2 23/43] drm/sun4i: backend: Detail the YUV to RGB values coding explanation
Date: Fri, 23 Nov 2018 10:24:55 +0100 [thread overview]
Message-ID: <20181123092515.2511-24-paul.kocialkowski@bootlin.com> (raw)
In-Reply-To: <20181123092515.2511-1-paul.kocialkowski@bootlin.com>
From: Paul Kocialkowski <contact@paulk.fr>
The values in the BT601 YUV to RGB colorspace translation are not
simply coded as multiples, but rather as fixed-point signed fractional
values on a given number of bits. Add an explanation about that.
Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
---
drivers/gpu/drm/sun4i/sun4i_backend.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c
index a39d8b75d76a..986bdb64521c 100644
--- a/drivers/gpu/drm/sun4i/sun4i_backend.c
+++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
@@ -48,8 +48,12 @@ static const u32 sunxi_rgb2yuv_coef[12] = {
/*
* These coefficients are taken from the A33 BSP from Allwinner.
*
- * The formula is for each component, each coefficient being multiplied by
- * 1024 and each constant being multiplied by 16:
+ * The first three values of each row are coded as 13-bit signed fixed-point
+ * numbers, with 10 bits for the fractional part. The fourth value is a
+ * constant coded as a 14-bit signed fixed-point number with 4 bits for the
+ * fractional part.
+ *
+ * The values in table order give the following colorspace translation:
* G = 1.164 * Y - 0.391 * U - 0.813 * V + 135
* R = 1.164 * Y + 1.596 * V - 222
* B = 1.164 * Y + 2.018 * U + 276
--
2.19.1
next prev parent reply other threads:[~2018-11-23 9:28 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-23 9:24 [PATCH v2 00/43] drm/sun4i: Support for linear and tiled YUV formats with the frontend Paul Kocialkowski
2018-11-23 9:24 ` [PATCH v2 01/43] drm/sun4i: Cleanup video/YUV source before enabling a layer Paul Kocialkowski
2018-11-27 8:31 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 02/43] drm/sun4i: frontend: Replace ARGB with XRGB as supported format Paul Kocialkowski
2018-11-27 8:31 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 03/43] drm/sun4i: Add TODO comment about supporting scaling with the backend Paul Kocialkowski
2018-11-27 8:31 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 04/43] drm/sun4i: backend: Add a helper and a list for supported formats Paul Kocialkowski
2018-11-27 8:38 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 05/43] drm/sun4i: frontend: " Paul Kocialkowski
2018-11-27 8:38 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 06/43] drm/sun4i: backend: Refine the logic behind using the frontend Paul Kocialkowski
2018-11-27 8:39 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 07/43] drm/sun4i: backend: Use a specific function to check if a plane is supported Paul Kocialkowski
2018-11-27 8:41 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 08/43] drm/fourcc: Add helper to check if a format uses a YUV colorspace Paul Kocialkowski
2018-11-27 8:49 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 09/43] drm/fourcc: Add format info helpers for checking YUV planes disposition Paul Kocialkowski
2018-11-27 8:49 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 10/43] drm/fourcc: Add format " Paul Kocialkowski
2018-11-27 8:49 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 11/43] drm/fourcc: Add format info helpers for checking YUV sub-sampling Paul Kocialkowski
2018-11-27 8:49 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 12/43] drm/fourcc: Add format " Paul Kocialkowski
2018-11-23 16:55 ` Ayan Halder
2018-11-23 17:23 ` Ville Syrjälä
2018-11-26 9:03 ` Paul Kocialkowski
2018-11-23 9:24 ` [PATCH v2 13/43] drm/sun4i: backend: Use explicit fourcc helpers for packed YUV422 check Paul Kocialkowski
2018-11-27 8:51 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 14/43] drm/sun4i: backend: Avoid counting YUV planes that use the frontend Paul Kocialkowski
2018-11-27 8:52 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 15/43] drm/sun4i: Rename sun4i_backend_layer_formats to sun4i_layer_formats Paul Kocialkowski
2018-11-27 8:52 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 16/43] drm/sun4i: frontend: Move CSC bypass setup to format update routine Paul Kocialkowski
2018-11-27 8:53 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 17/43] drm/sun4i: frontend: Add helpers for input data mode and pixel sequence Paul Kocialkowski
2018-11-27 8:53 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 18/43] drm/sun4i: frontend: Add proper definitions for format registers Paul Kocialkowski
2018-11-27 8:54 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 19/43] drm/sun4i: frontend: Determine input mode based on the number of planes Paul Kocialkowski
2018-11-27 8:55 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 20/43] drm/sun4i: frontend: Determine input format based on colorspace Paul Kocialkowski
2018-11-23 9:24 ` [PATCH v2 21/43] drm/sun4i: frontend: Add support for the BGRX8888 input format Paul Kocialkowski
2018-11-27 8:57 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 22/43] drm/sun4i: frontend: Add support for the BGRX8888 output format Paul Kocialkowski
2018-11-27 9:04 ` Maxime Ripard
2018-11-23 9:24 ` Paul Kocialkowski [this message]
2018-11-27 8:57 ` [PATCH v2 23/43] drm/sun4i: backend: Detail the YUV to RGB values coding explanation Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 24/43] drm/sun4i: frontend: Configure and enable YUV to RGB CSC when needed Paul Kocialkowski
2018-11-23 9:24 ` [PATCH v2 25/43] drm/sun4i: frontend: Apply format sub-sampling to CH1 dimensions Paul Kocialkowski
2018-11-27 8:58 ` Maxime Ripard
2018-11-23 9:24 ` [PATCH v2 26/43] drm/sun4i: frontend: Add support for packed YUV422 input formats Paul Kocialkowski
2018-11-23 9:24 ` [PATCH v2 27/43] drm/sun4i: frontend: Add support for semi-planar YUV " Paul Kocialkowski
2018-11-27 9:00 ` Maxime Ripard
2018-11-23 9:25 ` [PATCH v2 28/43] drm/sun4i: frontend: Add support for planar " Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 29/43] drm/sun4i: Make pitch even for GEM dumb alloc as per hardware constraint Paul Kocialkowski
2018-11-27 9:02 ` Maxime Ripard
2018-11-23 9:25 ` [PATCH v2 30/43] drm/fourcc: Add definitions for Allwinner vendor and VPU tiled format Paul Kocialkowski
2018-11-27 9:02 ` Maxime Ripard
2018-11-23 9:25 ` [PATCH v2 31/43] drm/sun4i: Add a dedicated ioctl call for allocating tiled buffers Paul Kocialkowski
2018-11-23 11:30 ` Brian Starkey
2018-11-23 12:52 ` Paul Kocialkowski
2018-11-27 9:03 ` Maxime Ripard
2018-11-23 9:25 ` [PATCH v2 32/43] drm/sun4i: Pass modifier to backend and frontend format support helpers Paul Kocialkowski
2018-11-27 9:13 ` Maxime Ripard
2018-11-23 9:25 ` [PATCH v2 33/43] drm/sun4i: frontend: Add support for tiled YUV input mode configuration Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 34/43] drm/sun4i: Add buffer stride and offset configuration for tiling mode Paul Kocialkowski
2018-11-27 9:24 ` Maxime Ripard
2018-12-04 13:30 ` Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 35/43] drm/sun4i: frontend: Add and use helper for checking tiling support Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 36/43] drm/sun4i: layer: Add tiled modifier support and helper Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 37/43] drm/sun4i: drv: Allow framebuffer modifiers in mode config Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 38/43] drm/sun4i: Move access control before setting the register as documented Paul Kocialkowski
2018-11-27 9:26 ` Maxime Ripard
2018-11-23 9:25 ` [PATCH v2 39/43] drm/sun4i: frontend: Add a quirk structure Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 40/43] drm/sun4i: Set the coef_rdy bit right after the coef have been set Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 41/43] drm/sun4i: Make COEF_RDY conditional Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 42/43] drm/sun4i: frontend: Move the FIR filter phases to our quirks Paul Kocialkowski
2018-11-23 9:25 ` [PATCH v2 43/43] drm/sun4i: frontend: Add A20-specific device-tree compatible and quirks Paul Kocialkowski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181123092515.2511-24-paul.kocialkowski@bootlin.com \
--to=paul.kocialkowski@bootlin.com \
--cc=airlied@linux.ie \
--cc=contact@paulk.fr \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-sunxi@googlegroups.com \
--cc=maarten.lankhorst@linux.intel.com \
--cc=maxime.ripard@bootlin.com \
--cc=sean@poorly.run \
--cc=thomas.petazzoni@bootlin.com \
--cc=wens@csie.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).