Resolution is probably the thing that gets folks confused the most, especially when it comes to printing.

First off, there are two different kinds of resolution when it comes to printing. There is print resolution and printer resolution. I’ll deal with printer resolution first so we can dismiss it.

Printer resolution is the resolution the printer uses to put down the teeeeeny, tiny little bitty drops of ink that make up one colored dot that represents one image pixel. For instance, my printer will print at several resolutions: 720 dpi (dots per inch), 1440 dpi, 2880 dpi. Choosing one of these just tells the printer how fine to lay down the ink to make the those drops of color. I use 1440 dpi printer resolution to make my prints. 2880 just uses more ink and I can’t see the difference. This is set in the printing dialog box, not Photoshop.

You may not have resolution settings like this for your printer. You may have choices like ‘Photo Quality’, ‘High Quality’, etc.

So that’s printer resolution. Now ignore it.

Print resolution is what drives people to an early stay at the rest home.

What you want to use to control the print resolution is Photoshop.

In Photoshop you get to the Image Resize dialog from the menu: Image>Image Resize. In Elements you get to it from the menu through Image>Resize>Image Resize. There are several options that I’ll get to in a minute.

First of all, what print resolution should you print at? That kind of depends on who you talk to. Some say that you should print at 360 dpi or 300 dpi for maximum quality. Truth is, you can’t tell the difference. Depending on print viewing distance, you can get away with printing as low as 180 dpi. I print all of my images at 240 dpi and I can’t tell the difference between prints made on my inkjet printer and those done through a photographic process. I get great quality, sharpness, all that stuff.

Technically, there is a difference between printing at 240 dpi and 360 dpi, but someone would have to look at the print through a magnifying glass to see the difference. People who do that are annoying. You don’t want to hang out with them.

So back to the Image Size control. This is what it looks like in Photoshop:

See ‘Constrain Proportions’ and ‘Resample Image’, those are the important ones.

First let’s make a small print. If you want to make a print that’s 4″ x 6″ printed at 240 dpi (or whatever resolution you want), first check the Resample Image box, this is what allows you to change resolution and print size. Unless your picture is already in a 3:2 aspect ratio, you’ll also need to uncheck the ‘Constrain Proportions’ box, otherwise you won’t be able to get the dimensions you want.

Then just fill in the Width, Height, and Resolution and click OK.

DON’T SAVE YOUR IMAGE WITH THESE SETTINGS, or you’ll overwrite your original. Save as a copy instead if you want to save it.

You’ll notice that when you fill in width, height, and resolution, the Pixel Dimensions at the top of the box will change. Those numbers will get smaller. So you won’t be using the full resolution of the original image to make the print. And you don’t need to.

If you wish to, you could uncheck the ‘Resample’ box and change the Width and Height. What will happen is that the Pixel Dimensions won’t change. What will change is the resolution. So instead of printing 4×6 at 240 dpi, you might be printing 4×6 at something like 960 dpi. This is a waste as the printer can’t use that resolution and will print at something like 360 dpi anyway, depending on the printer (Note, this is just what I remember reading somewhere, but I could have been drunk at the time or the source I was reading was wrong. But I’ve heard this more than once so it’s probably true. And I wasn’t always drunk when I’ve heard or read it.)

If you need to make a print that’s larger than the pixel dimensions your captured image will allow, just fill in those dimensions. Don’t go too far though. If your camera captures images that can print 8×12 at 240 or 300 dpi without changing anything in Photoshop, you can realistically upsize those images to 12 x 18 or even 16 x 24 at your chosen resolution. This is also dependent on the original image quality (focus, sharpness, etc.) And there’s software out there like OnOne’s Perfect Resize that will allow you to make huge prints.

So now your image is sized for printing at the size and resolution you want. Go ahead and print away. Color matching is an entirely different (and longer) conversation.

As far as your camera settings, shooting at the highest resolution/quality is the best practice. It’s easier to downsize images for printing than to upsize.

EDIT: If you want to know about pixels and the web,  Mathew Campagna from The Turning Gate has just posted an excellent treatment of the subject.