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Pixel Aspect Ratio
My last post lead into this one.
Any good sources for demystifying aspect ratios?
What harm can come from ignoring that the comp i just made isn’t the same as the psd layers I’m bringing in?
I’ve been command-clicking each layer, going into interpret footage, and setting the interpretation to the comps ratio, but i never used to (and i’d get distorted images that were to fat or long and rotated strangely), does this solve the problem?
I don’t even understand the problem. Square, non square, blah blah. At work they say “Oh don’t worry, when it’s imported to final cut it will go back to wide screen…” !?! So confused.
If there was a book specific to this, i’d buy it.
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4 Replies
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ae will handle the aspect ratio conversions, so you are usually best to leave them alone… later versions of photoshop will handle aspect ratios too, and allow you to work with non-square pixels and save a file with that aspect ratio embedded so when you import into ae, ae will handle it correctly. when ae doesn’t see an embedded pixel aspect, it assumes square, which is normally correct.
the only time you should set an image or footage to a pixel aspect ratio that is different, is if you know the pixel aspect ratio is wrong…. like you know the source was dv tape so the pixel aspect was .9, but ae thought it was square… then you should change it. otherwise let ae handle it. that way when if you bring in a square pixel psd and drop it into a dv/d1 comp ae will scale the image to look correct when it is displayed on tv.
you can toggle ae’s pixel aspect correction preview by clicking a little button that looks like a rectangle with a 2 headed arrow above it… it’s at the bottom of the preview window, towards the right side. it just gives a quick (rather choppy) view of what your comp will look like on tv.
Kevin Camp
Designer – KCPQ, KMYQ & KRCW -
[nothingboy] “I’ve been command-clicking each layer, going into interpret footage, and setting the interpretation to the comps ratio, but i never used to (and i’d get distorted images that were to fat or long and rotated strangely), does this solve the problem?”
You should never reinterpret your footage to have a pixel aspect ratio other than what it is supposed to have. If you created a PSD in Photoshop with Square Pixels, then that should be interpreted as Square Pixels in AE. Your composition, however, should have whatever pixel aspect ratio the device you’re compositing for has… 0.9 for NTSC, 1.07 for PAL, 1.2 for NTSC Widescreen, Square for Computers/Web.
Darby Edelen
DVD Menu Artist
Left Coast Digital
Aptos, CA -
You guys are wicked.
Okay so I should leave my files alone then… AE assumes square pixels on these files, and i’ve been re interpreting as D1/DV NTSC Widescreen. I will stop doing this.
BUT!
If i bring a file in with an alpha channel it will often look (a psd layer) distorted. The aspect ratio warps it. I can’t ignore this, even if it adjusts later on, can i?
A warped image will rotate strangely and look awful in the comp, am i to trust that it will unwarp?
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it should ‘unwarp’.
create a circle in photoshop, save it as a single layer psd and import into ae. create a dv/d1 comp and drag the circle into it. the circle should look like an oval (about 10% wider that tall).
rotate the circle 90 degrees. the circle should still look like and oval that is 10% wider than tall.
it will all look good in a broadcast monitor or on tv… like i said, you can toggle the pixel aspect correction button to se a circle as a circle, but the edges will look a bit choppy (this is only in the preview, the render will be fine).
Kevin Camp
Designer – KCPQ, KMYQ & KRCW
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