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The Beginner's Guide to Image Editing, Part 1

November 02, 2005 by
The truth about resolution

So you bought a cool new Firewire scanner, and a piece of software named Photoshop Elements came nestled snuggly in the box. Sweet! Now you can do fun things with photos! There's just one little problem: you have absolutely no idea where to start. Never fear, for the Beginner's Guide to Image Editing is here (thanks for the idea Kirk!).

In this tutorial series, we'll start with the very basics of image editing; that is, what you need to know before you dabble with any photos. From there we'll move on to resizing graphics for specific purposes, cropping, basic color correction, how to make selections, and so on.

Let us begin our journey by discussing The Mother of All Digital Image Editing Principles: image resolution.

Good graphics gone bad

Resolution problems plague beginners and some intermediate image manipulators alike. We've all seen it: a beautifully designed newsletter/flyer/web page ruined by an evil, pixelated, blocky, ugly graphic. Blech. Be it a logo, headshot, or The Fairy Godfather himself (shot at a recent renaissance festival); it’s lower quality than everything else and it stands out like a PC weenie at Macworld.

To get started, we need to define a couple of cryptic terms called pixel and resolution. Paying attention to these little jewels will serve as a tiny forcefield against evil, pixelated, blocky graphics.

What is a pixel?

A pixel is the smallest picture element of a digital image; it’s literally one piece of information. All digital images are displayed to you in tiny blocks (called pixels, sometimes referred to as dots) of color. Together they form an entire image. For example, if we zoom in on The Fairy Godfather at 700% (as frightening as that sounds), we can see that he is indeed comprised of individual dots-o-color.

What is resolution?

Think quality: Resolution refers to the sheer volume of information contained in your image, or more technically stated, the number of pixels (in both height and width) which make up an image. It’s expressed in ratio form (640 x 480 pixels) and in terms of dots per inch (dpi). The higher the numbers, the more information you have in the image; the greater its clarity and definition, the better it’ll print.

In the next installment I'll show you how to use Photoshop Elements' Image Size dialog box to change the resolution and thus physical dimensions of an image. Though that's for another time. Read on.

What’s the graphic’s purpose in life?

To print, or not to print, that is the question! Before you do anything to a photo or create a graphic from scratch, you must ask yourself, “What am I going to do with the image?” Inquiring minds, like your digital camera, scanner, and printer need to know. Are you ever going to print it? Ever ever ever? Consider all possibilities.

If you’re only going to use an image on the web, in a slide-show, in an email, or on a CD-ROM, you don’t need as much quality as you do for print. This means you can make images smaller and more download-friendly (smaller images download faster). Images that are destined to live only onscreen can be a mere 72 dpi, for that is all the information our monitors—and our wee little eyeballs—can compute.

A nice, online and email-friendly photo size is 320 x 240 at 72 dpi. (Forum peeps, are you listening?!!!)

In the printing realm...

Let’s say you’re going to print the aforementioned graphic. The next question is how? On what device? On what type of paper? At what size? Does it need to be enlarged? This information is best gleaned sooner rather than later.

If we were to print an image at the email-friendly size of 320 x 240 at 72 dpi, it will look about as good as the "bad quality fairy" above. To get a decent print without losing quality, we need to increase the dpi without altering the number of pixels in the image. Changing the dpi to 300 reduces the physical dimensions of the photo to postage stamp size (1.08 x .8 inches). Luckily, Photoshop Elements will do such size conversions for you, and we'll explore that process in depth in the next installment.

Most home inkjet printers will do a nice job with images of 225 dpi. However, if you’re sending something to a professional printer for output (like a magazine or business cards), they'll probably want 300 dpi. The goal is to get your image resolution to match that of your output device. Anything above it is technically overkill, though a higher number gives you a bit of pixel wiggle room and flexibility. (There are formulas which show you how to take the maximum output resolution of a printer and divide it by a number like how many stars are currently visible in the southern sky to get the proper resolution, yada yada. For now, just go with the numbers above and you'll be fine).

To be on the safe side, when dealing with a professional printer or service bureau, ask them what resolution they want. If they don’t know... run away, run away!

Shooting digitally

When shooting digital images, you’ll need to make sure you’re using the right image quality setting on your camera. Most cameras have settings of basic, fine, very fine, and in some cases, something rather alien called “raw” (requires a special plug-in in order for your image editing software to open them). Though digital cameras record images at a resolution of 72 dpi, the physical dimensions of the image (pixel height and width) increase as you go up in quality setting.

If you're going to print the image, shoot at the highest quality setting available. This will give you plenty of pixels to play with when resizing it in Photoshop Elements.

If you’re not going to print the image, you’re okay with the basic setting. This allows you to fit more photos on your memory card, as the file sizes are smaller.

Though a finer setting will increase the physical dimensions (and thus the amount of information/quality) of your image; they will take up more space on your camera's memory card (and subsequently your hard drive). The finer the setting, the more pixels and detail you have to work with, and the better the image will print.

Scanning

Before we wrap up Part 1, let's get some scanning basics out of the way by hopping over to The Skinny on Scanning (read it if you haven't done so already). You may find some of the numbers to be slightly different than what we discussed here, though that's because I like a little wiggle room when I scan an image.

In the next installment, I'll show you how to change the image size and resolution in Photoshop Elements.