Samples of Different Scan Resolutions

75 - 150 - 300 - 600 - 1200 dpi samples

75 dpi - approx 'full size' depending on your screen.  Not much detail - the cancel looks like a solid impression on the outer circle

150 dpi - satisfactory for most casual purposes.  Can now see the cancel breaking up, but note the background in the stamp image looks like a solid light brown.

300 dpi - now you can start to see finer detail.  Note how the background in the top left of the picture can now be seen to be a series of individual lines.

600 dpi.  Now you can see almost all the printing detail in the image.  Care to guess what printing process was used?  You probably couldn't tell with the 75 and 150 dpi scans, and could make a guess at 300 dpi, but it is only with this detailed 600 dpi scan that you know, for sure, that it is an engraved print, and therefore, Scott 2287, rather than a lithographed Scott 2291.

Lastly, a scan of part of the stamp (the image is getting too big) at 1200 dpi.  My HP ScanJet 6200C only goes up to 600 dpi of optical resolution, and at 1200 dpi it is starting to 'invent' extra information, with the net result being that although the image is bigger, it is starting to get fuzzier again because the extra size isn't being matched with extra resolution.