Measuring Frame Size And Resolution - Adobe PREMIERE 5 User Manual

344 APPENDIX A
Measuring Time and Frame Size

Measuring frame size and resolution

In editing digital video, frame size is also referred to as resolution. Several attributes of frame
size are important when editing video on a personal computer: pixel (picture element) and
frame aspect ratio, clip resolution, project frame size, and bit depth. It is also important
to understand the relationship between frame size and memory requirements. In general,
higher resolution preserves more image detail and requires more memory to edit. The
upper limit of useful resolution is usually dictated by the format on which the project is
ultimately delivered.
Aspect ratio
The aspect ratio of a frame describes the ratio of width to height in the frame dimensions of
an image. For example, the frame aspect ratio of NTSC video is 4:3, whereas some motion-
picture frame sizes use the more elongated aspect ratio of 16:9. Where appropriate, Premiere
provides options for preserving the aspect ratio of a clip or altering it to match the project
aspect ratio.
A frame using a 4:3 aspect ratio (left), and a frame using the wider 16:9
aspect ratio (right)
The aspect ratio of the frame is not the only area in which proportions are relevant. Some
video formats output the same aspect ratio but use a different aspect ratio for the pixels that
make up the frame. For example, the D-1 (CCIR-601) standard produces the same 4:3
aspect ratio as the Windows, Mac OS, and NTSC standards but uses rectangular pixels at a
resolution of 720 by 486 pixels. D-1 pixels in systems producing NTSC video are vertically
4
3
16
9