From: "Chris Zwar" <AE-List@media-motion.tv>
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Subject: Re: [AE] Dealing with super hot pixels in 32 bit
Date: Fri, 14 Sep 2018 08:40:08 +1000
References: <list-7149654@media-motion.tv>
To: After Effects Mail List <AE-List@media-motion.tv>
In-Reply-To: <list-7149654@media-motion.tv>
Message-Id: <498B86C3-2481-4C04-9707-ED9AF721C529@chriszwar.com>

Unfortunately it turns out they weren=E2=80=99t NaNs, although I=E2=80=99v=
e definitely had that problem before.  The matching article on your page =
suggests that NaNs are a result of bugs in the rendering software, if =
that=E2=80=99s correct then several years ago I was getting regular NaN =
pixels with renders from Arnold.  The current project I=E2=80=99m on is =
rendered with Vray.

But in this case they=E2=80=99re not NaNs, just super hot pixels.  I=E2=80=
=99m working on a battle scene and there=E2=80=99s lots of weapons and =
metallic armour and hence reflections/specularity.  Individual pixels =
will flicker from around the .5 mark up to 10 between frames.  This =
makes white dots flicker around, at first it looked like a type of =
watermarking! (wasn=E2=80=99t there a plugin vendor that used random =
dots to watermark demo versions, instead of the traditional red cross?)

While I=E2=80=99ve played around with 32 bit on several jobs, I=E2=80=99m =
still looking for the most comfortable AE tool to grade HDR.  The issue =
I=E2=80=99ve got is that there=E2=80=99s plenty of nice detail in the =
highlights that I want to retain.  There=E2=80=99s lots of goodness in =
the 1 - 3 range that I want to see, not clip.  Most layers have the HDR =
Highlight Compression plugin applied at various percentages - so far =
that=E2=80=99s been my most successful approach.  I recover the details =
I want through highlight compression then grade after that.  I am =
sometimes using the levels effect just to clip the values, but only =
after a certain point in the comp - it=E2=80=99s mostly to avoid =
weirdness with negative values.

I=E2=80=99m too far into the project to jump into Lumetri, but if =
anyone=E2=80=99s successfully used Lumetri to grade/tone map HDR images =
I=E2=80=99d love to know.


-Chris

> On 14 Sep 2018, at 2:01 am, Brendan Bolles <AE-List@media-motion.tv> =
wrote:
>=20
> On Sep 11, 2018, at 5:40 PM, Chris Zwar wrote:
>=20
>> Thanks, downloading now!
>> Wow Brandan has totally saved my ass (and the reputation of After =
Effects) with the current project I=E2=80=99ve been working on.  So many =
beers are owed.
>=20
>=20
> Haha, was that it, you had NaNs?
>=20
> If they were non-NaN hot pixels, I'd suggest you clip them by applying =
Levels with output clipping on and then set both Input White and Output =
White to whatever maximum value you wanted to clip.
>=20
> But if you've got NaNs you need NaNny!
>=20
>=20
> Brendan
>=20
>=20
> +---End of message---+
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