Canvas Size Issues?
by GnA Productions
on
Apr 6, 2007 at 4:19:52 pm
Hey...Ive got a question for all you after effects gods.
Why is it....if I make an image....say....640x480 in photoshop.....and then bring it over into a composition of 640x480 in after effects....they're not the same size. Either the canvas is too wide or too tall.
Is this a square pixels issue or something? I've come to this problem several times capturing video off my camcorder at 720x480....but when i bring it into a 720x480 composition.......it doesnt fit properally.....
Re: Canvas Size Issues? by wuzelwazel on Apr 6, 2007 at 5:10:17 pm
It is almost definitely a pixel aspect ratio issue. If you select your footage in the AE project pane it should give you some information about it (as well as a pretty little thumbnail) in the upper part of the pane. One of these pieces of information is the pixel aspect ratio in parentheses after the dimensions of the footage, e.g. 720 x 480 (0.90).
If you're working with 720x480 footage for NTSC then you want to make sure that the footage and your composition are using a D1/DV NTSC 0.9 pixel aspect ratio. To change this setting for the composition you're working in press cmd-k (ctrl-k), to change it for the footage you must first select the footage and then hit cmd-f (ctrl-f) to reinterpret your footage.
In addition, when working in non-square pixels I advise that you toggle on Pixel Aspect Ratio Correction (button just to the right of the Camera and number of views drop down in the comp pane).
Re: Canvas Size Issues? by moldyboot on Apr 6, 2007 at 5:14:35 pm
it is probably the pixel aspect ratio.... the dv footage you capture from your camcorder is nonsquare (.9 pixel aspect raition). for some reason ae is not interpreting it as such, but you can tell ae the correct pixel aspect by selecting the footage in the project window and right-clicking (or file menu)>interpret footage>main... here you can set the correct interpretation for pixel aspect (and other settings like field dominace--should be lower for ntsc dv). then when you put these into comps, ae will make the aspect correction for you, based on the comp's pixel aspect.
you can do the same for images. you can also create or convert nonsquare pixel images in photoshop cs2. when you create a new file in photoshop, the file parameter setting window that first opens will have a preset for dv and d1 standard (and others) that are .9 pixel aspect. ps will then handle the conversion of images that you drag into the file (say a square pixel jpeg from a digital camera).
note that if you work with 720x540 sqr pixel images in ps (which is a very common and often preffered sive to work in for video), when you put those in a d1 or dv standard comp in ae, you will also scale the image down to 90% (or right-click (or layer menu)>fit to comp). that is normal.
