[This article was first published in the September,
2004, edition of "Larry's FCP Newsletter.”]
This article grew out of last month's article on "Square
vs. Non-Square Pixels" describing the differences between computer graphics and television
graphics.
One of the mailing lists I read regularly is the Apple Final Cut Pro
Trainer's list. Recently, I was fascinated by a discussion of what's
the correct size to create graphics on your computer that import into
Final Cut with the correct proportions for video.
But, first, some background. The smallest element of a picture is
the pixel (short for "PICture ELement").
On your computer screen, all pixels are square. However, on a TV, pixels
are rectangles. This means that if you are creating graphics on your
computer to display as part of a video program, you need to compensate
for the differences in shape between the two pixel sizes.
If you don't compensate for these differences, the circles you create
on your computer will display as long, thin ovals on your TV set.
To make matters worse, Final Cut, in an effort to be helpful, adjusts
for these pixel differences differently, depending upon whether you
are importing a single layer graphic, such as a scanned photograph,
or a multi-layer PhotoShop document. AND, with the release
of Final Cut Pro HD, Apple changed the math behind how it calculates
this difference in shape, which means that the old numbers we used
to use may no longer be correct.
Into this discussion, Carl Jacobs, both an Apple Trainer and newsletter
subscriber, wrote a really nice piece that describes what you need
to know. I asked him to summarize the results exclusively for this
newsletter.
Carl writes:
A little-known SMPTE Recommended Practices document from 1995 (SMPTE
RP 187 -1995) both anticipates the Photoshop to FCP image workflow
and specifies the SMPTE recommended pixel aspect ratio for NTSC 4:3
(.904) and 16:9 Anamorphic (1.205) Unfortunately, FCP uses different
pixel aspect ratios of .888888888889 (8/9) and 1.185, respectively.
One can guess why Apple may have used different numbers (they were
unaware of the SMPTE doc and made some logical assumptions of their
own), but the implication for those of us who import Photoshop and
other square-pixel images into FCP is that using Apple’s numbers
based on FCP pixel aspect ratio will make images appear correct (a
circle is a circle) within FCP but they will be slightly
distorted when output to an NTSC monitor.
On the other hand, if we use the SMPTE numbers (or Photoshop’s
and After Effects’ presets which use SMPTE’s numbers)
then the image will look right on the NTSC monitor but will be slightly
distorted in FCP and will not match other images created in FCP.
The numbers break down like this:
Video Format
|
Final Image size
|
SMPTE recommends
|
FCP recommends
|
DV-NTSC 4:3
|
720x480
|
720x531
|
720x540
|
DV-NTSC 16:9 Anamorphic
|
720x480
|
868x480
|
853x480
|
601-NTSC 4:3
|
720x486
|
720x538
|
720x547
|
601-NTSC 16:9 Anamorphic
|
720x486
|
868x486
|
853x480
|
For more info on Apple’s numbers (including the numbers
for PAL video) go here:
http://docs.info.apple.com/article.html?artnum=36836
Before you tear out whatever hair you have left trying to
figure out which numbers to use, keep in mind that most if not all
NTSC displays and TV sets (which ultimately is what the viewer will
see your work on) are probably not geometrically calibrated anyway
and certainly not within the 2% difference between the two sets of
numbers.
Larry again. Carl did a great job
researching these numbers. However, I especially point out his last
paragraph. There's a point where the geometry (or lack thereof) of
the home viewer's set will have more impact than the size you create
your images.
If you are interested in a more detailed analysis, including specific "how-to" instructions
to determine the correct size to make Photoshop images look correct
when imported into FCP read the
longer version of Carl's article here.
And a large thank-you to Carl for taking the time
to write this up for all of us!
By the way, for those of you outside North America
scratching your heads about this, SMPTE (the Society of Motion Picture
and Television
Engineers) is the official committee that determines the engineering
specifications for NTSC video. There are similar governmental bodies
that set the standards for PAL video. And, like NTSC, PAL video uses
a non-square pixel. However, a PAL pixel is a different size than an
NTSC pixel (which should, of course, surprise no one). It's aspect
ratio is 1:1.06.
Apple's web site provides the necessary conversion numbers for PAL
video. You may talk amongst yourselves to decide if Apple's numbers
are correct.
This article is from the September, 2004, issue of "Larry's
FCP Newsletter," a very cool FREE monthly Final Cut Pro
newsletter -- subscribe at Larry's web site: www.larryjordan.biz.
Larry Jordan is a post-production trainer and consultant, as well
as an Apple-Certified Trainer in Digital Media with over 25 years experience
as producer, director and editor with network, local and corporate
credits. Based in Los Angeles, he's a member of both the Directors
Guild and Producers Guild.
Text copyright 2004 by Larry Jordan. All rights reserved. May not
be reprinted without permission.
Larry Jordan is a post-production consultant and an Apple-Certified Trainer in Digital Media with over 25 years experience as producer, director and editor with network, local and corporate credits. Based in Los Angeles, he's a member of both the Directors Guild of America and the Producers Guild of America.
The information in this article is believed to be accurate at the time of publication. However, the author assumes no liability in case things go wrong. Please use your best judgment in applying these suggestions.
The opinions expressed in this article are solely those of the author. This newsletter has not been reviewed or sanctioned by Apple or any other third party. All trademarks are the property of their respective owners and are mentioned here for editorial purposes only.
Links to my website home page or this article are welcome and don't require prior permission.
