Re: [Discussion] Subpixel rendering issues with compressed video output formats

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What Vitor is referring to is when the graphics cards sample down the
resolution of certain channels, typically in the YUV color space, but
sometimes maybe in RGB, eg. encoding every 4x4 block of blue channel only,
2x2 of red, and 1x1 of green.

It's as if you JPEG compress the subpixel-rendered image and decode it...

behdad
http://behdad.org/


On Mon, Jun 9, 2025 at 12:11=E2=80=AFPM Alexei Podtelezhnikov <apodtele@gma=
il.com>
wrote:

>
> If you are referring to color fringing when the text is moving and RGB ar=
e
> firing up with some delay. I have no idea how to synchronize it. This is
> likely out of scope of FreeType.
>
> > On Jun 9, 2025, at 14:01, Alexei Podtelezhnikov <[email protected]>
> wrote:
> >
> > =EF=BB=BFVitor,
> >
> > Frankly, I can hardly relate your problem description to font rendering=
.
> Can you possibly rephrase it? In FreeType speak LCD rendering is just
> triplicated for 3 arbitrary color channels with slight differences
> depending how these channels are spatially shifted. Regular antialiasing =
is
> just a special case assuming that three channels are not shifted at all.
> Note that FreeType does not assign color to the channels.
> >
> > Alexei
> >>
> >>
>
>

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<div dir=3D"ltr"><div>What Vitor is referring to is when the graphics cards=
 sample down the resolution of certain channels, typically in the YUV color=
 space, but sometimes maybe in RGB, eg. encoding every 4x4 block of blue ch=
annel only, 2x2 of red, and 1x1 of green.</div><div><br></div><div>It&#39;s=
 as if you JPEG compress the subpixel-rendered image and decode it...</div>=
<div><br></div><div><div dir=3D"ltr" class=3D"gmail_signature" data-smartma=
il=3D"gmail_signature">behdad<br><a href=3D"http://behdad.org/" target=3D"_=
blank">http://behdad.org/</a></div></div><br></div><br><div class=3D"gmail_=
quote gmail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">On Mon, =
Jun 9, 2025 at 12:11=E2=80=AFPM Alexei Podtelezhnikov &lt;<a href=3D"mailto=
:[email protected]">[email protected]</a>&gt; wrote:<br></div><blockquote=
 class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px so=
lid rgb(204,204,204);padding-left:1ex"><br>
If you are referring to color fringing when the text is moving and RGB are =
firing up with some delay. I have no idea how to synchronize it. This is li=
kely out of scope of FreeType.<br>
<br>
&gt; On Jun 9, 2025, at 14:01, Alexei Podtelezhnikov &lt;<a href=3D"mailto:=
[email protected]" target=3D"_blank">[email protected]</a>&gt; wrote:<br>
&gt; <br>
&gt; =EF=BB=BFVitor,<br>
&gt; <br>
&gt; Frankly, I can hardly relate your problem description to font renderin=
g. Can you possibly rephrase it? In FreeType speak LCD rendering is just tr=
iplicated for 3 arbitrary color channels with slight differences depending =
how these channels are spatially shifted. Regular antialiasing is just a sp=
ecial case assuming that three channels are not shifted at all. Note that F=
reeType does not assign color to the channels.<br>
&gt; <br>
&gt; Alexei<br>
&gt;&gt; <br>
&gt;&gt; <br>
<br>
</blockquote></div>

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