Numbered image sequences store video clips as individual still image files. Each image
file has a number in the filename that indicates where it fits into the sequence. In a film
clip that’s been digitally scanned, each file represents a single frame. In a video clip that’s
been converted to an image sequence, each file contains both fields of a single video
frame, with the upper and lower lines of the image saved together.
Image sequences use the same variety of file formats as still image files. Some of the most
popular formats for saving image sequences include SGI, BMP, JPEG, TIFF, and TGA. Like
still image formats, many of these support alpha channels, which are used by Motion.
Because image sequences have been around for so long, they remain the
lowest-common-denominator file format for exchanging video across editing and
compositing applications. Although QuickTime is increasingly used to exchange video
clips between platforms, image sequences are still used, especially in film compositing.
As with QuickTime video clips, you can mix image sequences of different formats, using
different frame sizes, pixel aspect ratios, frame rates, and interlacing. For more information,
Supported File Formats
Any imported image sequence must contain three or more digits of
padding—for example, “imagename.0001.tif.”