So lets get to pixel aspect ratio. Current CRT displays present an image to the viewer line by line, until an entire image is displayed. For interlace displays such as a TV, every other line is skipped the first time around and then filled in the next time. What we want to look at is how each line is sent to the front of the CRT (the screen). Each line is discrete. There is a set number of lines displayed top to bottom and is the same for VHS, DV, NTSC over the air broadcast, etc. On each line, an analog signal is sent to the CRT gun which send electrons from one side of the screen to the other. The horizontal component of the image is not discrete, but is a continuous analog signal.

What does this mean for us? Well, it means no matter what the left to right size of your frame of video is, it is going to be displayed in the same area of your TV. Having a bigger frame size of video does not make your TV bigger! If you have a high end TV camera that is rated at 800 lines (left to right), that means you can distinguish 800 lines left to right on the TV (if the TV can also display those 800 lines). If you have a low quality VHS, you may only get 250 lines (left to right) on the screen. This is a by product of the recording technology and the frequencies it can handle in the analog domain.

For DV video, the standard is 720 pixels wide and 480 pixels tall. That image size ratio is 1.5 but is displayed on a 1.333 image ratio device (your TV). This is where the idea of "rectangular pixels" and "pixel aspect ratio" (PAR) comes from.

TV has discrete lines top to bottom and DV has 480 pixels top to bottom. So we assume that a TV has 480 lines top to bottom. If that is true, then we use the 480 height to find the width of a 4:3 image. 480 / 3 * 4 = 640. This is standard VGA resolution and you see this quite a bit when working with video.

So now you ask "How do I get my still images to look correct using my video editing software?" I wish the answer was simple, and it could have been if Adobe did not have a bug in their Adobe Premiere 6 software.

The best way to handle this is to crop or matte your images to a 4:3 image size ratio. Then import you images into Premiere. Turn off "Maintain aspect ratio" in your images. This will resize your image to 720x480 and fill up the frame of video. It will look stretched left to right on your monitor if viewed without any correction. The frame will be "squeezed" left to right back to the proper 4:3 ratio when it is displayed on the TV.

What about widescreen TV? Now that HDTV is hitting the airwaves, more and more people are buying widescreen TV's. DVD players support widescreen output that is called anamorphic The frame size is still 720x480, but the content is stretched vertically rather horizontally. When the video is played back to the 16:9 screen, the video is then squashed back down vertically. If you want your stills to be displayed correctly on a 16:9 screen, just crop or matte the image to an image size of 16:9 and follow the same procedure and settings described above.

I hope this helps you out with how to handle your "digital media". Just make sure your images match the width to height ratio of your FINAL device output (4:3 or 16:9), then let Premiere resize to DV 720 x 480.

If you have any comments (questions, did I miss anything, do I need to add something, you think this is wrong, it really helped you out) PLEASE let me know. jeremy@jeremymoore.com