Re: Digital photo frames comparison

["Jon Whiten" <jon.whiten@xxxxxxxxx>]

What about

Pixels Wide X Pixels High
-------------------------------------
Diagonal X Diagonal

This will give a measure that is comparable across devices.

;oj


On 11/12/06, Paul Gordon <paul@xxxxxxx> wrote:
>
> Because I was thinking that I need to work out the number of pixels in
a
> known area to compare one display against another.
> My thinking was thus:
>
> If the resolution is known, lets say 640x480, then I can simply
multiply
> those two number to give me the total number of pixels on the whole
> display - in this example 307,200. OK so far?
>
> I'm then thinking that two different displays with the same
resolution,
> but a different size panel will be vastly different, - 640x480 on a
> 5-inch screen will probably look quite good, on an 8-inch screen will
> likely look quite pants, so I need to then calculate the number of
> pixels in a common amount of screen area to see which panel has the
> greatest pixel density...
>
> Therefore I reckon if I know the surface area of the screens, lets say
> one is 5-inches by 3-inches = 15 square inches, the other is 8-inches
by
> 5-inches = 40 square inches, then I can calculate:
>
> 307,200 divided by 40 = 7680 pixels per square inch
> 307,200 divided by 15 = 20,480 pixels per square inch
>
> Thus I can see that the smaller screen has nearly 3 times the number
of
> pixels in a given area (1 square inch), and thus is likely to be
> "better" (by which I really just mean sharper I suppose).
>
> Yes, I had realised that there are both square and non-square pixels
out
> there, but I was deliberately avoiding that consideration to keep
things
> relatively simple!
>
> The only bit I needed to fill in was how to deduce the X & Y
dimensions
> from the diagonal using Pythagoras' theorem.
>
> Does anyone think this logic is flawed?
>
> Cheers.
>
> Paul G.
>
>
>
> > -----Original Message-----
> > From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
> Of
> > Andy Laurence
> > Sent: 12 November 2006 17:42
> > To: UKHA_D Group
> > Subject: RE: [ukha_d] Digital photo frames comparison
> >
> > Steve Cuthbertson <mailto:steve@xxxxxxx> wrote:
> > > On Sun, 12 Nov 2006 14:52:58 +0000, I wrote:
> > >
> > > Lots of deleted arithmetic...
> > <snip>
> >
> > More importantly, as the diagonal of the screen is proportional
to the
> > area, why bother working out the area for comparisons?
> >
> > Cheers,
> > Andy
> >
> >
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