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how do i convert ppi to dpi for professional printer?

marz c , Dec 29, 2005; 12:18 p.m.

Hello, I'm new to Photo.net. Is there a conversion for ppi to dpi? The printer I am sending my project to has requested "we recommend 100 dpi at full size" for my image resolution. If they are printing, isn't 100 dpi going to be quite grainy? And, in photoshop, I don't see an option to ensure that my photo is a certain dpi. Obviously I can control the ppi, but I don't know how to make sure my image is 100 dpi for the printer...

anyone know how to do this? thanks so much!

Responses

Patrick Lavoie , Dec 29, 2005; 12:31 p.m.

According that you are printing in a news paper like, and the printer ask you for the correct word, DPI is Dot Per Inch, PPI is Pixel Per Inch. Theres is no < conversion > to make. It is very important to make sure that when you talk to people you mean, both of you, the same things. Now if you want to know how many PPI you need to get 100 DPI, its pretty simple; take the number the printer give you and multiply it by 2 (if you are a paranoi kind of guy) or 1.5 is way OK. So he need 100 x 2 = 200 PPI. The reverse is simple to, assuming that when people ask you for a 300 PPI file, that should mean they print at around (300 /2) 133 or 150. And yes if they are asking you for a 100 dpi, meaning 100 ppi in there head, yes it will be pretty noisy or maybe they printing on a large format inkjet and they think that 100 is enough. have fun: )

Alan Olander , Dec 29, 2005; 01:36 p.m.

When printing with an inkjet printer it's best to use an image that's sized to 300ppi, give or take a little. For example (using 300ppi), if you have an image that is 2400 pixels by 3000 pixels, you will get an 8" x 10" print (2400/300 x 3000/300). Dots per inch should really refer to what the printer is laying down in ink dots and has really nothing to do with ppi. Whatever your printer means, it doesn't sound like you would get a very good print out of it.

I'm not really sure what Patrick is talking about, either! ;)

Dennis Price , Dec 29, 2005; 02:16 p.m.

Dear Marz, welcome to Photo.net.

There is much confusion and misinformation on the subject of ppi and dpi. Although well-defined terms, they often mean different things to different people, and their correct usage is by no means universal.

If you are sending your project to a commercial printer, may I suggest that you contact them for a clear explanation of their standards, specs, and expectations for file submission.

While the answers you get on this forum may be well-intentioned, they are no substitute for a direct dialog with your printer, especially if you are paying them to produce a job.

Best,

Roger Krueger , Dec 29, 2005; 04:55 p.m.

dpi = ppi. The only place they're used to mean vaguely different things is on inkjet printer specs. Even there, the printer's physical dpi has no bearing on how you set your file up. You just need to realize that an inkjet advertising "1440 dpi" isn't really resolving that many pixels of artwork.

No offset printer I've EVER encountered (in 20+ years of doing print production) uses "dpi" to refer to a halftone screen, that's always "lpi", lines per inch.

100 dpi at full size is reasonable for very large output, like a billboard, a bus wrap or a trade-show poster. The fact that he specificied "at full size" makes me suspect this is what you're doing, since people commonly work on huge projects at half or quarter scale.

Resampling in Photoshop is irrelevant, except for things (like text) actually created after the resample. If your original picture only delivers 40 dpi at actual size, resampling isn't going to save you.

If you have MORE than 100 dpi, do NOT throw it away. The 100 dpi is intended as a minimum. Text especially looks pretty raggedy at that low a resolution. Your printer may squawk a little about getting a bigger file, but go for 150 dpi or 200 dpi if you've got anything that can benefit from the higher resolution.

Trade-show graphics in particular do have people walk right up to them. The one time in my life I let a printer talk me down to 100 dpi on a trade-show graphic (pleading "faster print time" when I was in a hurry) my client complained about how the text looked. The fact that the printer's account rep said "it looks fine to me" meant nothing.

And I am giving you the benefit of the doubt--your first post on photonet being on a topic that always promotes vehement disagreement makes me suspect this is a troll. If so, I guess I bit.

marz c , Dec 29, 2005; 05:09 p.m.

thank you all so much for helping. i am indeed doing a trade show banner, sized 33.31w by 84h. i am sending to a graphics company, but they aren't printing it offset. and, apparently the "image resolution" refers to the entire image, which i am using Illustrator to create. i'm sending them the .ai files anyway, and linking my photos and graphics, so it should workout ok. any other things i should keep in mind with this dpi/ppi stuff?

thanks a lot for your help though! it was quite perplexing at first.

John Pelafigue , Sep 13, 2011; 12:18 p.m.

The graphics design types who contact me specifying dpi should know better, that photographers deal in ppi, not dpi. I simply give them the pixel dimensions and let them figure whether it'll work for them. I used to sweat it the way the OP did in this case, NO MORE!

Patrick Lavoie , Sep 13, 2011; 12:28 p.m.

not all photographer deal in ppi or dpi .. they mostly deal in 8x10, 11x14 or whatever size.. then they assume that to have excellent quality they need to put that @ 300 dpi/ppi (mean the same thing in a conversation.. )

Graphic designer (and most photographer, at least the one that are in business since a long time maybe not the newer generation) work with final print size in mind... i never heard of a magazine giving is spec as pixel per pixel, but in inches.

I dont know what a 3200 x 3200 is myself, but i know what is a 10x10inch @ 300 ; )

I simply give them the pixel dimensions and let them figure whether it'll work for them.

and they probably wont call you next time because they will certainly think that if you can't figure out how to give a 8x10 @ 300ppi you must be a junior.... even if you give them the same exact thing in pixel dimension..sometime it is easier just to give people what they want without any fuzz .. and certainly it is best for you when they pay you for it.

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