RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI

["Austin Franklin" <darkroom@ix.netcom.com>]

> >> 2. If you want to print the picture, the maximum size you can
> >> print is limited to the number of pixels expressed at 300 ppi.
> >>  I always set the output resolution of Vuescan to 300dpi.
> >I have no idea what you mean by that...would you please elaborate?
>
> OK.  I don't have any files to work with here so I'll work with
> some theoretical
> numbers.  Suppose you scan a 35mm frame at 2700dpi (spi if you prefer :)
> and get a file containing 3000x2000 pixels.  If you want to print the file
> at 300dpi (or 300 pixels per inch)

Why would you want to output at a fixed 300 PPI?  If you are outputting to
an inkjet printer, you are best to just choose your image output size and
let the PPI output to the printer fall where it may.  If you do any resizing
of the PPI to make some fixed number, then you are resampling, which
degrades the image.  If you just let the PPI fall where it may (providing
you are above 180+, if even 240), then you only get one “processing” of the
image, namely the halftone algorithm in the printer driver (converting PPI
to DPI ;-)...and therefore less image degradation.  Am I misunderstanding
you perhaps?

> 2. As I mentioned earlier, some printers give quite good results at lower
> dpi.  Epsons seem to work quite well at 240dpi because of the
> integer relationship
> with the 1440dpi native dot size.

That’s pretty much been proven to by a myth.  It is true, to some degree,
for lineart, but not at all for halftoned images.