>>>>> "Jon" == Jon Winters <[EMAIL PROTECTED]> writes:

    Jon> On Fri, 12 Apr 2002, Amit Mukherjee wrote:
    >> Hi,
    >> Can anyone tell me the difference between dpi, ppi and
    >> lpi ? If my intention is to print a picture measuring
    >> 8"x10", at what resolution should I scan ?

    Jon> dpi = dots per inch
    Jon> ppi = pixels per inch
    Jon> lpi = lines per inch

DPI is normally used for scanners, printers, and monitors.  LPI is
normally used for half-tone screened images.  A 100 LPI half-tone
image corresponds to a much higher DPI rating.

    Jon> to know the minimum you need to scan you'll need to know what
    Jon> sort of dpi your printer is capable of printing.

    Jon> Lets say its an ink-jet that'll handle 1000dpi To print an
    Jon> 8x10 without having to scale the image up or down to make it
    Jon> fit you'll need to scan...

    Jon> 8000 x 10,000 pixels!

    Jon> Pretty easy eh?

For most practical purposes, 300dpi for a color print is more than
good enough.  Scaling the image to fill whatever resolution you need
for your printer should cause no problems.  If you have a 300dpi image
(at print scale), and produce a fiery from it, you will be completely
happy with the results.  For photographs, I typically scan the 35mm
negatives at 2400dpi and print up to 8x12 with no perceptible loss.

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