Now that computers have become the equipment of choice for SSTV, image resolution is no longer limited by memory constraints. Although most SSTV operation involves color images of approximately 320 x 240 pixels, there is a whole range of new modes for sending and receiving 640 x 480 and even 800 x 600 color pictures. The tradeoff in using these modes is now time, not memory capacity:

1. A 640 x 480 image has 4 times the resolution of a 320 x 240 picture and will require four times as much time to transmit.
2. Color images require from 2-3 times the time required for a grayscale image of the same resolution.
3. The rate for transmission if the pixels in an image line cannot go much above 2000 pixels/second without exceeding the bandwidth permitted for SSTV operation.
4. Pictures must be completed in less than 10 minutes to meet the legal requirement for station identification.

There is nothing that can be done, in practical terms, with #1 and 2. Attempts to fudge on item #3 are not only skirting legality, but they also fail to deliver the resolution you might expect. Compare a Scottie 1 and a Scottie 2 picture if you want to see that "faster" does save time but at a severe reduction in quality - the goal in increasing resolution in the first place! Finally, although you could play with 10 minute modes on VHF and UHF, pictures have to be a lot shorter in duration to be acceptable and practical on most HF bands.

I won't analyze the various modes here, but I do want to show the kind of quality that you can get on VHF and the upper HF range, if conditions and crowding make it practical to spend 3-7 minutes to transmit an image. Unless otherwise noted, the various sample images represent transmissions from KF7OH as received at my Michigan QTH on 15, 12, and 10 meters. Most are P5 mode, although the KB4YZ example is a P3. These are "big" image files, so to save time, I have set up thumbnails to let you select the images you might actually want to look at. To see an image at full-resolution, simply click on the highlighted image label. When you are through viewing a particular image, use your browser's return arrow to get back to this page.