Optimum Printing Settings. HELP!

ashcran25 · May 29, 2012

Hi Guys!

I'm kind of a newbie, so bear with me.

When I take pictures with my Canon 60D and upload them to Adobe Bridge, the settings are 72ppi, 8.34 MB, 5184 x 3456 (I picked one picture to use as an example,but they're all along these lines.)

I've read that 72 ppi is far too low for printing great looking photos.

What exactly should the above settings be changed to and how do I do that in Photoshop CS3.

Thanks!

Judobreaker · May 29, 2012

**Sighs**

DPI is not PPI.
The correct name is in fact PPI.

PPI stands for pixels per inch. The PPI on an image is useless as long as it is not printed, it doesn't do squat.
When you're printing however the PPI value will determine how many pixels of the image will be printed on an inch of paper.
Basically this means that at 300 DPI an image of 600x600 will measure 2x2 inches.

DPI is something else entirely!
It stands for dots per inch and it refers to how many actual physical dots of ink per inch are placed on the paper by the printer.
If a printer has the ability to print at 600 DPI this will mean that 600 dots of ink will be placed on an inch of paper, regardless of the PPI settings.
This simply means that if the PPI setting is 300 and your printer DPI is 600, each image pixel will be 4 ink dots (2 dots wide, 2 dots high).

As for the OP's question:
There are a lot of opinions on which PPI is the minimum for a good quality image.
It usually comes down to simply trying a few values and figuring out which you like best.

300 PPI is commonly accepted as being the top border at which you can see the quality difference, anything above and the human eye can't see any increase in quality.
This is why most printing companies ask for 300 PPI images.
There are of course purists who claim they can still see an increase and therefore print their images at something like 600 PPI, although I highly doubt there's a lot of people that can actually see the difference.

I myself usually try to print at 300 PPI but am willing to compromise if my image simply is too small for 300 PPI.
My personal guideline is that anything above 150 PPI is usually acceptable in cases I don't care about quality that much. My border for decent quality lies at 200 PPI.
Anything below 150 PPI is simply too low.

Crollo · May 29, 2012

Your images aren't scanned, so the DPI value is meaningless.

So you could print something with the resolution of 2 dpi and it will have no improvement over 900 dpi. Interesting.

KmH · May 29, 2012

If you use a good print lab, their RIP software will take care of the issue for you.

Why Canon sets 72 ppi as their default is a mystery. At any rate you can change the ppi setting with editing software like GIMP, Photoscape, or Photoshop.

Most printing companies do not ask for 300 PPI.

Mpix.com's chromogenic print machines max out at 250 ppi, and they are willing to bet their reputation by printing any photo that has had it's ppi set a slow as 100 ppi.

There are no magic, one-size-fits-all values. as prints get bigger, they are viewed from further away and ppi can be reduced without a loss of image quality as seen from the further viewing position.

table1349 · May 29, 2012

HP seems to think so:
Once you've decided what you'll do with your scanned photo, you'll be able to determine the best scanner resolution and file format. Let's review these common scanning terms:
Scanner resolution is measured in pixels per inch (ppi) or dpi (dots per inch)–the more pixels or dots, the sharper the image. Where dpi is used to describe print quality, ppi refers to the digital image itself.

The difference between dpi and ppi While there is a difference between dpi and ppi, many people (and even manufacturers) use the terms interchangeably. Scanners usually measure resolution in terms of ppi, while many HP printers and All-in-ones use dpi to refer to print quality

Introduction to photo scanning

table1349 · May 29, 2012

For the OP. A couple of good links on digital photos and printing.

All About Digital Photos - The Myth of DPI
Tutorials on Color Management & Printing

ashcran25 · May 29, 2012

Right now I'm cropping my photos to the preset crop of 4x6, 300 ppi., 1800x1200. It saves anywhere from 600k to 2.5MB. Is this right? If i just change the size to 300ppi and keep the size it takes out of the camera, it takes forever to edit in Photoshop and saves much bigger, anywhere from 8-10 MB.

Thanks for the responses!

Helen B · May 30, 2012

Graystar said:
From the Adobe TIFF 6.0 Specification.

There are actually three fields relating to this value in the TIFF file structure. There's ResolutionUnit, XResolution, YResolution. This is because scanners are able to scan at different X and Y resolutions. Scanners can have X and Y DPI ratings that differ.

The TIFF spec calls them 'pixels per ResolutionUnit', not 'dots per ResolutionUnit'. The later PNG spec also refers to 'pixels per unit' [length] not 'dots per unit'. Though the earlier JFIF spec does refer to dots per inch or dots per cm, it does call them measurements of pixel density.Strange, huh?

Manufacturers do seem to use them interchangeably, but ppi seems clearest when describing the resolution of an image file at a given size while dpi works well for describing printer resolution.

I think that it is worth finding out the optimum ppi(s) for the printer you will be using, if you want the best quality and greatest control over your image. For example most Epson inkjet photo printers print at 1440 dpi or 2880 dpi, and so they work very well with 288 ppi, 360 ppi and 720 ppi image files. Canons print at 1200 dpi and 2400 dpi so seem to work better at 300 ppi, 400 ppi and 600 ppi. It does depend on the printer software (the RIP), however - so an Epson that does a pixel-for-pixel print at 288 ppi with the Epson driver may do it at 300 ppi with a third party RIP.

Laser and LED exposure units for digital C-prints (Durst Lambda, Theta; ZBE Chromira, Polielettronica LaserLab etc) can have native resolutions between 200 dpi and 1200 dpi (of course the 'dots' are different from those of inkjet printers) and the exact resolution may not be the nominal figure - eg 300 dpi may be the nominal figure and 304 dpi the exact figure. I noticed that when I used ezprints - my prints were coming out slightly smaller than they should have, and that was why.