Does 480x640 pixels equal 480 lines of video resolution?

... or to put the question in the reverse sense: when capturing a

480x640 pixel image of a video frame onto my computer, do I capture

all information present in the image?

Yes. 640X480 is about the limit of res for a video grab. And that's if you can grab a progressive scan frame. Grabbing a frame of Interlaced video will give you 640X480, but each of the two fields of video are recorded 1/30th of a second apart, leading to weird artifacts. See my website for examples of what progressive scan video grabs look like

 

www.vfs.com/~peter

Peter McLennan

Short anwswer: No.

 

First, it is usually 640 pixels left to right and 480 pixels top to bottom. So the number you are trying to relate would be the 640, not the 480.

 

Second, lines are a measure of the ability to distinguish closely spaced lines drawn from top to bottom, stacked left to right. The more lines you can cram across the screen and still distinguish as unique, the higher the video resolution. But remember that each line has to have space before the next line in order to be able to distinguish it. Therefore, pixels can't correspond exactly to lines. A crude conversion I've seen used is a ratio of ~1.4 pixels per line. So a 640x480 image would have similar resolution as a video signal of about 450 lines. This is much more than either 8mm/VHS (240) or broadcast TV (330). Hi8/S-VHS is about 400. D8/DV is about 500.

And then you have to look at the television capabilities. Most televisions display 'around' 640x480 viewable and can cut a little bit off of the top and sides as well. 640x480 is considered (generally) what is viewd on the tv screen, though.