You need to divide the number of dpi by the number of colours plus
black to get the raw ppi measure as each printer pixel is a composite of
the colours. Calculating the actual ppi measure is much more difficult
as dither and anti-alias algorithms are applied to each pixel.
Printers such as the Epson 1290 have a 2880 dpi setting but there is no
visisble difference between 2880 dpi and 1440dpi and 2880 does not
seem to be recommended by Epson. The maximum resolution of
the Epson 1290 is about 150 to 180 ppi.
Graham
"Paul D. Sullivan" <dudeboyz_at_hotmail.com> wrote in message
news:joa7d.15387$Cn.4536_at_trnddc04...
> I have a 5 megapixel image that has 426 dpi of actual data on a
> 6"x4" print (2556 x 1704 actual pixels).
>
> If I have an Epson printer that does 2880 x 720 dpi, will that
> printer actually be able to print / resolve 426 actual dpi when
> it prints out the original image onto high-gloss photo paper?
>
> Or is it not able to actually print 426 dpi?
>
> I ask because someone told me that they thought the Epson could
> only resolve 360 dpi max, which is a divisor of the Epson print
> resolutions and that it could not resolve anything above that in
> actual printing.
>
> Any help would be appreciated.
>
> Thanks
>
>
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