In a couple of places, I've seen folks mention "increasing resolution" in the context of digital after-shot processing. This isn't truly possible. The best resolution you can manage is with the object of interest as large as possible in the frame, and with the quality or resolution settings as high as possible. These settings determine how good your picture can be. Any kind of "zooming in" or resolution increase, in post-processing, is nothing more than inventing new pixels to go inbetween real ones. This is called interpolation. The "invented" pixels can give the impression of better quality in some circumstances, but are not true or accurate. You might say they are "fuzzy guesses".

There is something called digital image "sharpening" which is an editing technique that emphasizes the edges, or contrast balance. Again, if the quality is bad to start with, this won't help "create" better detail in a picture; it will just help bring out what is there.

In a related sense, "digital zoom" is just an automatic cropping routine. No new pixel data is created. Existing pixels might be doubled, even interpolated, but it is really just the same picture with the edges cut off, and blown up. In general, a digital photography program can do a better job of this, with greater control. There isn't any good reason to use digital zoom while taking shots. Crop it later for best results. Use the "optical" specifications to compare cameras, and even scanners.

Video cameras almost always have fewer pixels to work with. Stills with these will never have the resolution of decent still digital cameras, because they are usually limited to less than 500 X a smaller number of pixels. That is much less than a megapixel.

If you are looking for the very best in resolution, and don't need color, a monochrome CCD with a given megapixel rating will give you much sharper pictures. (complicated) A 35mm camera with good film might be said to have an approximate resolution of 5 megapixels, but with the slower shutter speeds required, may give worse results than a 3 MP digital. Depends on the light, height and a bunch of other issues.



As far as I can tell, the limit to resolution effectiveness is the degree of vibration. I'd be interested in your experiences with reducing vibration with building techniques, but in another thread. (not talking about image stabilization here...)

(disclaimer: simplified for beginners!)