On 26 Aug 2005 05:14:51 -0400, Warp <war### [at] tagpovrayorg> wrote:

>Stephen McAvoy <mcavoys[at]aol[dot]com> wrote:
>> Screen size, 1000 pixels width fills a 10 inch wide screen gives to
>> some minds, 100 ppi. 
>
>  But I don't understand how an image file can have a PPI.
>  The computer probably doesn't even know the physical size of your
>monitor. How can it figure out its PPI? And even if it figured it out,
>what would it change in the image file? Would the image file somehow
>change with a different PPI?

Of course you are right I know pixels are dimensionless but the
average user thinks a pixel does have two dimensions. I am talking
about people needing something tangible to hang an idea on, to get a
working concept.  
Printers are used to working in picas or points and they have
dimensions so it follows (erroneously) graphic images in ppi have a
dimension.

I think PPI is a left over from DTP.

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