# algorithm: printer resolution * print format = number of megapixel to be used

Discussion in 'Digital Photography' started by Timur, Dec 22, 2003.

1. ### TimurGuest

I read several articles (both on magazines and on usenet posting)
stating the maximum size that one can print a digital picture (given a
fixed number of megapixel) without losing quality. None of them though
was explaining the proper (scientific way) to calculate that...

I assume that there should be one, I was thinking something like:

the number of DPI the printer is capable of times the size we want to
print should be not minor than the number of megapixel. Of course it
is not working like that (just try with your favourite number).

One ratio that I saw quite often is that 3megapixel allows maximum
8x10 (inches) printout. (BTW, in my very personal experience also
10x12 are good at that resolution)

For those who believe that the number I provided is correct: how do
you make the calculation to prove that? Is it just practical
experience?
For those who think that the numbers are wrong: how do you proof your
point?

Thanks a lot,
Timur

Timur, Dec 22, 2003

2. ### HarveyGuest

See http://digigraphica.com/oped/03/resolution.shtml It explains the
calculation. Basically at a printer setting of 200 dpi you have, for an 8
by 10, 1600 by 2000 dots or 3.2 mp.

"Timur" <> wrote in message
news:...
> I read several articles (both on magazines and on usenet posting)
> stating the maximum size that one can print a digital picture (given a
> fixed number of megapixel) without losing quality. None of them though
> was explaining the proper (scientific way) to calculate that...
>
> I assume that there should be one, I was thinking something like:
>
> the number of DPI the printer is capable of times the size we want to
> print should be not minor than the number of megapixel. Of course it
> is not working like that (just try with your favourite number).
>
> One ratio that I saw quite often is that 3megapixel allows maximum
> 8x10 (inches) printout. (BTW, in my very personal experience also
> 10x12 are good at that resolution)
>
> For those who believe that the number I provided is correct: how do
> you make the calculation to prove that? Is it just practical
> experience?
> For those who think that the numbers are wrong: how do you proof your
> point?
>
> Thanks a lot,
> Timur

Harvey, Dec 22, 2003

3. ### Don StaufferGuest

Re: algorithm: printer resolution * print format = number of megapixelto be used

The problem here is that modern error diffusion dither algorithms do not
use a FIXED number of printer dots per pixel. Old 'mock halftone'
printing did, say an array of 4 x 4 printer dots per pixel. But modern
algorithms maintain only an average number of dots per pixel, and even
that average number is somewhat variable.

Sidenote- seems funny to use the term modern to exclude things that we
used only about fifteen years ago or so

Timur wrote:
>
> I read several articles (both on magazines and on usenet posting)
> stating the maximum size that one can print a digital picture (given a
> fixed number of megapixel) without losing quality. None of them though
> was explaining the proper (scientific way) to calculate that...
>
> I assume that there should be one, I was thinking something like:
>
> the number of DPI the printer is capable of times the size we want to
> print should be not minor than the number of megapixel. Of course it
> is not working like that (just try with your favourite number).
>
> One ratio that I saw quite often is that 3megapixel allows maximum
> 8x10 (inches) printout. (BTW, in my very personal experience also
> 10x12 are good at that resolution)
>
> For those who believe that the number I provided is correct: how do
> you make the calculation to prove that? Is it just practical
> experience?
> For those who think that the numbers are wrong: how do you proof your
> point?
>
> Thanks a lot,
> Timur

--
Don Stauffer in Minnesota

webpage- http://www.usfamily.net/web/stauffer

Don Stauffer, Dec 22, 2003
4. ### TimurGuest

"Harvey" <> wrote in message news:<>...
> See http://digigraphica.com/oped/03/resolution.shtml It explains the
> calculation. Basically at a printer setting of 200 dpi you have, for an 8
> by 10, 1600 by 2000 dots or 3.2 mp.
>

Thanks a lot, Harvey! This was exactly what I was looking for.

regards,
Timur

Timur, Dec 26, 2003