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sick artist
Obsessive-Compulsive (I) Inmate

From: South Brent, Devon, UK
Insane since: Apr 2002

posted posted 04-22-2002 01:23

Hello all, just doing an "art-foundation" and I have many images, mostly still in the form of un-scanned photos or 35mm negs that I want to tweak and enlarge quite BIG so they take up a lot of space in my "portfolio" but am not sure how to go about it.

Got PS 6 and I have just obtainned a copy of Altamira Genuine Fractals Print Pro 1.0 - Understand it is quite good.

When it comes to enlarging I have heard many things: trading off quality to having images of a managble size for your computer; things about what dpi the eye can see and what dpi photographic paper is; things about industrail printers printing off at 300dpi, and really, I have no idea. - But before I do start to play with my pictures, I want to make sure I am scanning at the correct rez, using the best canvas size and dpi and stuff so I do not waste my time rendering things that the eye cannot see, nore spend ages working on images that will just look, well, shite.

Now I have one or two photos that i would like to print off to poster size. - Is that possible?

I know of photographic developers that turn most file types on any format into a "photo" by projecting it and stuff. - I am guessing that is better than a 300dpi printout as being "analouge", a high rez image would look good and a 35mm neg would look better still... or not.

Confused and in a rush. - Any of that make sence?

HELP appreciated



Maniac (V) Mad Scientist

From: Mi, USA
Insane since: Aug 2000

posted posted 04-22-2002 01:30

Wow! Sth Brent? no way! heh small world sicko! Welcome to the Asylum!

Got friends in Sth Brent. Nice little village. Is the Packhorse still there?

I wish I could help with your question, but I am not much of a print expert. Hopefully someone will come along and give you some good answers.

Generically speaking, scan at a high res, at least 300 if printing, perhaps higher if you are wanting to enlarge stuff. Gives PS more info to work with , but like you said, you will be getting some huge files.

Good luck and hope you get the answers you need

[This message has been edited by vogonpoet (edited 04-22-2002).]

Lunatic (VI) Mad Scientist

From: the Psychiatric Ward
Insane since: Sep 2000

posted posted 04-22-2002 01:48

Yes... Scan big... bigger than 300. One thing you DO NOT want to do is to enlarge things digitally in PS. That makes much Yuck and pixelation... So Scan really high... Try some different settings, but deff biggah than 300.

. . .

Nervous Wreck (II) Inmate

From: victoria, bc
Insane since: Sep 2001

posted posted 04-22-2002 04:58

not sure how much use my answer will be as well, but i'll give it a try.

i work in a repro shop in canada, and we have three large poster printer machines (ultrachroma novajets for the most part and i think an old HP printer as well). we do not normally recommend a higher DPI output than 150 at FINAL SIZE, since the printers extrapolate the rest. the larger file size of say, a 300 dpi scan does not give a visually better poster than a 150 dpi output. i've even seen some really nice 72 dpi posters come off that thing, but that was done by a professional design studio that knew how to set up their files for max color reproduction.

i think the first thing you need to do is have a heart to heart talk with whoever/whatever is outputting your poster files and find out what the machine specs are. the smaller color machine(s) we run (11x17 or smaller) have a print spec of 400 dpi (CMYK) but you can half that resolution and still get a decent print. the larger machines have "true" output at 600 dpi (extrapolates to 1200) and run on CcMmYK heads (can't remember if is the magenta or the yellow that's doubled). does this help any?

Tyberius Prime
Paranoid (IV) Mad Scientist with Finglongers

From: Germany
Insane since: Sep 2001

posted posted 04-22-2002 08:31

sorry that I must contratict you sexylyon,
but quite a few scanners get over the 'real' 150dpi nowadays
without interpolating.

sick artist
Obsessive-Compulsive (I) Inmate

From: South Brent, Devon, UK
Insane since: Apr 2002

posted posted 04-22-2002 17:49

Wow, some quick replies. Sorry about "posting twice" - didn't realise that everybody checks different groups, although I fail to see how that made me a "sickko"


Cheers for the help guys, but you haven't really helped me much. I really what to know what image size and dpi I can work with in photoshop in order to print out at poster size. - With a HIGH quality? - That is really what I am after.

Most posters look crap close up. - Anyone know what sort of printing professionals "art prints" are done with? (Those that have been digitally inhanced that is.)

And Yo, Vogonpoet: yurp Pack Horse still there, but under different ownership in the last year - Nice pub. - I am designing South Brent T-shirts. We're going for the big time! Put that place on the map. - Joke - But probably shouldn't talk over the message boards - It annoys some people (quite rightly I suppose), so before I am called a sickko and banned, I will stop typing.

Later, Rob.


Maniac (V) Mad Scientist

From: Mi, USA
Insane since: Aug 2000

posted posted 04-22-2002 21:48

heh, well I only called you a sicko cos you are using it as a sig? lol no worries, yah double posts here is not appreciated. The forums are set up so that posts kinda fit into there various topics

You got anything to do with SBADS? lol

hang around the asylum, lots of good info here!

Nervous Wreck (II) Inmate

From: Melbourne, Australia
Insane since: Dec 2001

posted posted 04-23-2002 15:42

Tyberius - I don't think sexylyon was referring to scanners - he was referring to printers. Big difference.

Back to the original poster - as someone has already suggested, you need to talk to the printers (several if possible) who will be printing your posters. They will know what resolution your scans will need to be for their printers to work best for that size.

There is a difference between the various resolution units used in scanners, monitors and printers, and they are not interchangeable and they don't all refer to the same thing. A commercial printing machine may output at 1200 dpi, but the graphics file from which they are printed needs to be only 300 ppi. One pixel does NOT translate into one ink dot. Have a look at for an explanation of LPI (the resolution term used for the imagesetters that make the films used on commercial printers), DPI ( the term used for laser and inkjet printers), SPI (used for scanners) and PPI (used for monitor display).

That all said, vogonpoet's recommendation for scanning at 300 spi is fine IF you are printing the scan at the final image size. You are obviously not, and will be taking your scan into photoshop to increase its dimensions. This will be where it can get tricky. Assuming the commercial printer has a line frequency of 150 lpi (which is what I think sexylyon was actually referring to - please correct me if I am wrong), and this is probably about average for commercial printing. The rule of thumb for scanning resolution is 2 x LPI, which in this case is = 300 spi. But in turn this is assuming the SAME size will be used for printing. If you are increasing the final size to 400% of the original size, you will need to scan at 4 x 300 = 1200 spi to still reatin the 300 ppi after increasing the size i.e. when you increase the dimensions of the image (which will automatically decrease the resolution - unless you ask PS to interpolate - not a good idea for an increase of this magnitude) you will still have a decent enough resolution for printing.

Your poster may be way bigger than 400% increase over the original, but it will probably be impossible to scan either at this scale and/or at any higher resolution (even if the scanner says it can - what it is really doing is interpolating - not the same thing). So it rapidly becomes a tradeoff between the highest resolution you can get from your scanner at the largest upscaling it can do and increasing the size in Photoshop and still retain a decent resolution from which to print your poster. And it is impossible to get a poster size print (whatever size that may be) that is made from a digital file, without getting some pixelation.

Another thought - you have said most posters you have seen look very pixelated. This will be the case for most posters that are printed (as opposed to those made photographically). But that is usually OK, as most people view posters from a distance - and not up close, which is where you have to be to actually see the individual ink dots. They look fine (and the pixelation is not obvious) when viewed from a distance away that enables you to see the whole poster at once. But ask your printer what resolution he recommends you should do your original scan knowing the size of the original photo.

[This message has been edited by Eggles (edited 04-25-2002).]

Maniac (V) Inmate

From: The Land of one Headlight on.
Insane since: May 2001

posted posted 04-24-2002 17:18

Thanx Eggles. I've been *trying* to wrap my brain around this info for what seems 'forever'. It's all a bit clearer now. Great link too. and I see he's still a bit confused after 5 years.

Maniac (V) Mad Scientist

From: Mi, USA
Insane since: Aug 2000

posted posted 04-27-2002 23:05

exellent information Eggles Thanks for sharing !

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