MIME-Version: 1.0
Date: Wed, 16 May 2012 22:02:42 -0400
Message-ID: <CAN0dPSTb54fy9gz6jADqu870DC_tKuY8cGgJcQ5FoOmktufK+Q@mail.gmail.com>
Subject: Perfect luma gradients in YUV for Blu-ray
From: Sixtus Beckmesser <sbeckmesser@gmail.com>
To: AE-List@media-motion.tv
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1. My assignment: to make some test patterns that will appear on Blu-ray,
the authoring system of which requires 8-bit YUV 4:2:2 files of some kind
(I've been using AVI files as rendered by CS5.5 and now CS6 Cloud)
2. What I'm starting with: RGB still frames (usually TIFFS) with pixel
values corresponding the digital video standard (16-235). To be sure that
each pixel has the expected value, these still frames were calculated
algorithmically.
3. The problem: YUV files made from such still frames of black-to-white RGB
gradients end up with repeated pixel values or skipped pixel values (the
gradient is not "monotonic"). I am assuming that this is because of
round-off effects in the formulas used to get from RGB to YUV (I may be
wrong on this).
4. Restrictions as to the solution: a. must be software based, b. must be
free or very cheap, c. must produce the EXACT results I need. i.e. PERFECT
gradients in Y, no skipped values, no repeated values -- and in a file
format usable by the Blu-ray authoring system.
5. I guess what I need is a file-conversion system in which I can simply
designate the contents of one color channel of an RGB signal (which are
identical in black-to-white gradients) as Y and which will stick in the
appropriate values in for U and V (0 in the case of monochrome test
patterns). Anybody come across something like this? Is there a way to do
this with anything contained in CS5.5 or CS6?

--Sixtus

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1. My assignment: to make some test patterns that will appear on Blu-ray, t=
he authoring system of which requires 8-bit YUV 4:2:2 files of some kind (I=
&#39;ve been using AVI files as rendered by CS5.5 and now CS6 Cloud)<div>
2. What I&#39;m starting with: RGB still frames (usually TIFFS) with pixel =
values corresponding the digital video standard (16-235). To be sure that e=
ach pixel has the expected value, these still frames were calculated algori=
thmically.</div>
<div>3. The problem: YUV files made from such still frames of black-to-whit=
e RGB gradients end up with repeated pixel values or skipped pixel values (=
the gradient is not &quot;monotonic&quot;). I am assuming that this is beca=
use of round-off effects in the formulas used to get from RGB to YUV (I may=
 be wrong on this).=A0</div>
<div>4. Restrictions as to the solution: a. must be software based, b. must=
 be free or very cheap, c. must produce the EXACT results I need. i.e. PERF=
ECT gradients in Y, no skipped values, no repeated values -- and in a file =
format usable by the Blu-ray authoring system.</div>
<div>5. I guess what I need is a file-conversion system in which I can simp=
ly designate the contents of one color channel of an RGB signal (which are =
identical in black-to-white gradients) as Y and which will stick in the app=
ropriate values in for U and V (0 in the case of monochrome test patterns).=
 Anybody come across something like this? Is there a way to do this with an=
ything contained in CS5.5 or CS6?</div>
<div><br></div><div>--Sixtus</div>

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