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R. A. Prado" Cc: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Chun-Kuang Hu , Philipp Zabel , Matthias Brugger , AngeloGioacchino Del Regno , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, daniels@collabora.com, ariel.dalessandro@collabora.com, kernel@collabora.com Subject: Re: [PATCH 07/11] drm/colorop: Introduce HLG EOTF Message-ID: <20260206105102.1208fff9@eldfell> In-Reply-To: <20251223-mtk-ovl-pre-blend-colorops-v1-7-0cb99bd0ab33@collabora.com> References: <20251223-mtk-ovl-pre-blend-colorops-v1-0-0cb99bd0ab33@collabora.com> <20251223-mtk-ovl-pre-blend-colorops-v1-7-0cb99bd0ab33@collabora.com> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="Sig_/Z3McZGD/cduzL_hjq1GrAml"; protocol="application/pgp-signature"; micalg=pgp-sha256 --Sig_/Z3McZGD/cduzL_hjq1GrAml Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tue, 23 Dec 2025 16:44:48 -0300 N=C3=ADcolas F. R. A. Prado wrote: > Introduce definition of a hybrid log-gamma electro-optical transfer > function for 1D Curve colorops. >=20 > Signed-off-by: N=C3=ADcolas F. R. A. Prado > --- > drivers/gpu/drm/drm_colorop.c | 1 + > include/drm/drm_colorop.h | 10 ++++++++++ > 2 files changed, 11 insertions(+) >=20 > diff --git a/drivers/gpu/drm/drm_colorop.c b/drivers/gpu/drm/drm_colorop.c > index fafe45b93ff8..a19e03fb9c7c 100644 > --- a/drivers/gpu/drm/drm_colorop.c > +++ b/drivers/gpu/drm/drm_colorop.c > @@ -79,6 +79,7 @@ static const char * const colorop_curve_1d_type_names[]= =3D { > [DRM_COLOROP_1D_CURVE_BT2020_OETF] =3D "BT.2020 OETF", > [DRM_COLOROP_1D_CURVE_GAMMA22] =3D "Gamma 2.2", > [DRM_COLOROP_1D_CURVE_GAMMA22_INV] =3D "Gamma 2.2 Inverse", > + [DRM_COLOROP_1D_CURVE_HLG_EOTF] =3D "HLG", > }; > =20 > static const struct drm_prop_enum_list drm_colorop_lut1d_interpolation_l= ist[] =3D { > diff --git a/include/drm/drm_colorop.h b/include/drm/drm_colorop.h > index ee6454b08b2d..8ec98521607d 100644 > --- a/include/drm/drm_colorop.h > +++ b/include/drm/drm_colorop.h > @@ -126,6 +126,16 @@ enum drm_colorop_curve_1d_type { > * The inverse of &DRM_COLOROP_1D_CURVE_GAMMA22 > */ > DRM_COLOROP_1D_CURVE_GAMMA22_INV, > + > + /** > + * @DRM_COLOROP_1D_CURVE_HLG_EOTF: > + * > + * enum string "HLG" > + * > + * Hybrid log-gamma transfer function. > + */ > + DRM_COLOROP_1D_CURVE_HLG_EOTF, > + Hi, if you read ITU-R BT.2100[1], you will see that the HLG EOTF has three parameters: the system gamma, the display nominal peak luminance, and the display black luminance. You cannot define a HLG EOTF or its inverse without these parameters. One might assume to derive the system gamma from the peak luminance, but I would like to leave that as a free parameter if possible, because I'm not convinced the formulas for it are universally applicable. The HLG OETF on the other hand is a fixed function. Did you mean that instead? [1]: https://gitlab.freedesktop.org/pq/color-and-hdr/-/blob/main/doc/specs.= md#itu-r-bt2100 Thanks, pq --Sig_/Z3McZGD/cduzL_hjq1GrAml Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEJQjwWQChkWOYOIONI1/ltBGqqqcFAmmFq3YACgkQI1/ltBGq qqfkthAAl9JVF0BXYzyrmP1Q4T70bzj+epbVNcVjVbZlOwqrh+7gVLz7rrchimpN Sngz1zHLFa91+4ZkuzzGGPqxeCDOVhr0eraz6lrraMo0cWzQdtgfTkKLexw8t4ds 67U5dv/QBYdDTfQRlxlMGM9hXtG044wNJk0QCzeQQvXSSY3sNNzCVf47JvW4VqW/ /P3VfzkIP/VyPQqfeX+OFqthjrnMv0wZLR1e5JxzYtk+bXxV7b+KR249uLy61ddN 4OGn3X2iufMMXyzY9WEq3nOMhhtWG4pzux2KE4OabdbwPRI+fsUadSnVMFQjs7eo nSD2mFTXG5DW4UNWnnrWeZKdZee74i+G2G8ojWS0zHqFZ9cRjr7WsAi50xbfl1du tLZKuHwOuX1kPgzEmMaNwrzlT/J1ROuSq/tRd3EXdXu6jqK4Abive/XDu1Nkltwt MwWkOqnuQ3gnVoGcsEw6Gk71EBl96JlQf1JFBE23FnaarllJXwYYZZVmDtwH1hMx LWb9YcDcFeKa+qcEsvvVrWZmP9umpN5h4BkJpLypuAKsq5+o6OnnUapHpc0EyLxD vqsVV/NZJyPXlMhyLcO/DUSefJHZKFZvShxZRXi+DRu7K3utFMvq8Qg9mZaJyByG CN7kNQAdDQM0ELz7I3pIEleHpeyC3HI80/AA94FgWoh1tdLgTQU= =jHqA -----END PGP SIGNATURE----- --Sig_/Z3McZGD/cduzL_hjq1GrAml--