[ This article was first published in the Feb/March, 2008, issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe. ]
NOTE: The image scaling described in this article only affects output from Final Cut Pro version 6.0.2. Starting with version 6.0.3, images export using the rectangular scaling of video. This means that the warning at the end applies only to version 6.0.2.
With the release of Final Cut Pro version 6.0.2, Apple quietly changed the way it handles exporting still images; and, I suspect, also image sequences.
Almost all video formats use rectangular pixels to create their images (this includes DV-NTSC, DV-PAL, HDV, DVCPROHD, and XDCAM-HD). However, the computer uses square pixels for all its images – both print and web. (For a fuller discussion of this, read this article.)
This means that, prior to 6.0.2, any freeze frames you export from Final Cut need to be altered in Photoshop, or another graphic application, to convert them from a rectangular pixel aspect ratio to a square pixel aspect ratio. While not hard to do, many new users don’t understand pixel aspect ratios, so they couldn’t figure out why their images looked stretched.
The process of creating freeze frames (or “still frames,” both terms are valid) hasn’t changed since about forever:
The newly-frozen frame appears in the Viewer with a default duration of 10 seconds. (You can change this duration in Final Cut Pro > User Preferences > Editing tab — Still / Freeze duration.)
This newly-created freeze frame is temporary, you either need to edit the Viewer clip back into the Timeline, or drag it from the Viewer into the Browser to store it for later. If you load anything into the Viewer before editing the freeze frame, the freeze frame will disappear.
So far, no surprises. This works the same as always.
To export a freeze frame also remains the same:
By default, Final Cut will export the image as a PNG, which is a nice uncompressed file format.
So far, no surprises. This works the same as always.
However, with the release of version 6.0.2, Final Cut now changes the aspect ratio of the clip during export.
In the past, the image would export at the video aspect ratio. DV-NTSC, for example, would export as 720 x 480. Now, however, Final Cut converts the image from a video aspect ratio to the square pixels used by the computer. In other words, the 720 x 480 DV still frame is resized automatically to 640 x 480.
If your goal is to export a still frame and use it on the web or in print, this aspect ratio conversion is a good thing, because the image is ready to go upon export, no resizing is necessary.
If, on the other hand, you are exporting a still to use as a reference – for example, in Photoshop to determine the placement of DVD button overlays, this changed aspect ratio makes working with stills that are going to be reimported into video a REAL problem.
And there’s no way to turn this resizing off.
DV-NTSC is automatically scaled to 640 x 480. 720p DVCPRO HD is automatically scaled to 1280 x 720, and 1080i HDV is automatically scaled to 1920 x 1080. None of these images are at their native size.
I sent a note to Apple requesting that they give us the option of changing the aspect ratio during export. For now, however, you need to know that exporting has changed so you don’t get surprised when your images come out a different size than you expect.
UPDATE – March 6, 2008
Andy Field writes:
An excellent warning about exporting freeze-frames and the square pixel aspect ratio
However — there’s no solution or “what to do about this” when importing into video.” …Is there a fix in Photoshop to re-export out with the proper aspect ratio.
Larry replies: Andy, there’s a work-around, but not a fix, as the workaround decreases image quality
With the freeze frame open in Photoshop, and assuming you are working with NTSC DV 4:3:
One Response to Creating Freeze Frames and Exporting Stills from FCP 6.0.2
guess I don’t understand – in viewer , selected a frame to freeze, put into th e timeline then dragged into the browser- and it didn’t take – disappeared in the bowser stayed in the viewer. waht am I not getting? Please.
thank you
gg