Resolution calculation for Billboards and so on

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Tue, 06 May 2008 12:31 Go to next message
barleby28 (Photoshop begginer)
Hi, this is my first post about printing issues.
Right now I'm using the next formula to calculate the resolution for "small" format prints (i.e 21cm x 29.7cm):

Final res = lpi x 2 x ampliation/reduction factor (in %)
This way I'm getting reasonable values like 600dpi.

QUESTION is:
If I use same above formula for Big Formats like billboards, photo-calls etc I'd obtain incredibly huge file sizes (and my PC would get knocked down). So: How can I calculate/Know the final Res of my art knowing beforehand the final size of the art work (billboards and so on) ??

Any rule/formula/tutorial-link ??
Thank you very much in advance
Tue, 06 May 2008 12:50 Go to previous messageGo to next message
J_Maloney (Photoshop expert)
Your equation is sounds ok. Billboard lpi is around 10 - 20.

So: How can I calculate/Know the final Res of my art knowing beforehand
the final size of the art work (billboards and so on) ??




You can't. That's why this profession is so awesome.

J
Tue, 06 May 2008 12:54 Go to previous messageGo to next message
curt_young (Photoshop expert)
I have seen other posts where those making billboards use 100-300 dpi as they are intended to be viewed at a distance.
Tue, 06 May 2008 13:20 Go to previous messageGo to next message
dave_milbut (Photoshop expert)
I think you're misremembering curt. i believe phos and bob l have said if they're going to be large images viewed at a distance the ppi can be much lower. 100 or less. i could be wrong, but i don't think so. ;)

one of the billboard guys is sure to chime in soon to clear it up.
Tue, 06 May 2008 13:26 Go to previous messageGo to next message
J_Maloney (Photoshop expert)
300 ppi is way, way too high (so is 100). 100 ppi for posters viewed across a room. Across the highway, and I would think 50 ppi would be a ridiculous, gonna-piss-off-my-vendor-but-what-the-hell number.

But again, 2 x lpi is a good rule.

Ask your vendor.
Tue, 06 May 2008 15:18 Go to previous messageGo to next message
dave_milbut (Photoshop expert)
Ask your vendor.




that's what it boils down to. thanks j.
Tue, 06 May 2008 17:36 Go to previous messageGo to next message
Bob Levine[1] (Photoshop expert)
> i could be wrong,

You certainly could

> but i don't think so. ;)

You're not.

For a billboard, you might well be able to get away with 15-25 ppi.

Rule one for this stuff is to talk to the printer.

Bob
Tue, 06 May 2008 17:53 Go to previous messageGo to next message
Phosphor (Photoshop expert)
Back when I was doing them, our big printers were pretty slow, finicky and cumbersome, but still cranked out some pretty amazing images. And the RIP took our work, rasterized and resampled to 18 dpi, sometimes 36 dpi.

We generally set up our Photoshop files at a scale of 1/4 in. = 1 ft.

Computers are faster and more robust, RIPs are better, and the printers are a lot more sophisticated.

As has been advised: Talk to your service provider.
Wed, 07 May 2008 22:28 Go to previous messageGo to next message
dave_milbut (Photoshop expert)
You certainly could




<Col. Klink>HOGAAAAAAN!!!</CK>
Thu, 08 May 2008 16:08 Go to previous message
Art (Advanced Photoshop user)
I did a 14 by 40 foot billboard at 10 dpi, and they said that was more than
adequate.

Truth is, for most billboard viewing, 4 dpi would be plenty.

LED billboards and giant TV screens often use 1 LED/pixel per inch, or even
..5 per inch. In such cases each pixel is simply a tiny bright dot in the
middle of a two inch square. As you get close to an LED display, the dots
will suddenly fail to fill the pixel area, and the image will all but
disappear (to you). I saw an LED TV in an airport the other day, maybe 5 x
8 feet, whose resolution seemed to be about 5 dpi, falling apart at about
fifty feet.

One full size billboard manufacturer claims VGA resolution. That's 600
pixels wide, right? At 40 feet, that's 15 dots per foot, or 1.25 dpi.

So really, on a billboard that big, there's no reason to ever go above 10
dpi. Look at what a tenth of an inch is, and imagine it on a billboard
fifty feet in the air.


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