What is “interpolated” resolution on a scanner?
Many scanners claim things like 4800dpi “interpolated” resolution. If you didn’t pay thousands of dollars, this resolution isn’t really there, and isn’t really that useful. Unless you’re trying to get really fine details out of a small piece of a photo that’s in really sharp focus, more than 300 dpi is usually a waste of time and memory. Interpolated resolution means that the scanner will scan one line 1/300th of an inch wide, then move 1/4800th of an inch, then scan the next 1/300th-inch line, then subtract the difference. This doesn’t always work perfectly, and takes up lots of resources. Having said all that, there are expensive scanners, particularly “slide” scanners, which do have incredibly fine resolution. Using such fine resolution should be limited to very small images or parts of images, otherwise your file size will get huge, quickly. A scanner which does 8000dpi (they exist!
Many scanners claim things like 4800dpi “interpolated” resolution. If you didn’t pay thousands of dollars, this resolution isn’t really there, and isn’t really that useful. Unless you’re trying to get really fine details out of a small piece of a photo that’s in really sharp focus, more than 300 dpi is usually a waste of time and memory. Interpolated resolution means that the scanner will scan one line 1/300th of an inch wide, then move 1/4800th of an inch, then scan the next 1/300th-inch line, then subtract the difference. This doesn’t always work perfectly, and takes up lots of resources. Having said all that, there are expensive scanners, particularly “slide” scanners, which do have incredibly fine resolution. Using such fine resolution should be limited to very small images or parts of images, otherwise your file size will get huge, quickly. A scanner which does 8000dpi (they exist!), scanning an image one millimiter square, will produce a 315-by-315 pixel image, which will require
