Image resolution remains one of the great mysteries to hobbyist photographers; there's one setting for computer viewing and another for print output. Here's how it works.
I can't resist starting this chapter with an anecdote. Usually, I wouldn't, but I feel that this story sets the tone for the entire chapter.
About a year ago, after teaching a two-hour digital photography seminar, I was fielding questions from attendees while packing up my equipment. One gentleman approached me and said, "I have just one question for you. How do I change the resolution of my pictures without changing their dimensions? I know there's one little thing I need to do, but for the life of me, I can't remember what it is."
This guy had patiently sat through an entire seminar, probably about stuff he already knew, just so he could ask this question afterward.
I reopened my laptop, launched Photoshop, and showed him the magic box that he needed to uncheck. His eyes lit up, he grabbed my right hand, and he shook it vigorously. "Thank you, thank you!" he exclaimed and ran out the door. Most likely, he headed directly home and went to work.
For me, that experience sums up Photoshop for digital photographers. You know there's some way to accomplish everything you want to do, but for the life of Moses, you can't figure out half of them. Or, as in the case of my student, you can't remember what you already know.How to adjust picture resolution for printing falls squarely into that category for many photographers. This hack will solve that problem for you.
Your Camera's Resolution
Resolution is expressed in dots per inch (dpi) or pixels per inch (ppi). The higher the ppi, the more densely packed the pixels are, and the higher the resolution. Because of the inherent differences in various media, printing requires higher resolution than computer viewing.
Your digital camera is basically a miniature computer that contains a built-in scanner. It scans its images at 72 ppi. That happens to be the same resolution at which most computers display their images. So, going from digital camera to computer is like going from apples to apples. If you were always going to view your pictures solely on a computer, that would be the end of this conversation. But chances are, you want to make prints too. Prints don't look so good at 72 ppi. The ideal printing resolution for photo quality starts at 200 ppi. So how do you get there from here?
Working with Image Size
Open your picture in Photoshop and find the Image Size command. In Photoshop Elements, the path is Image Resize Image Size. In Photoshop CS, the path is Image Image Size. You'll notice in the dialog box that Pixel Dimensions is the top section and Document Size is the middle area. Pixel Dimensions shows you the current size of the image at the current resolution. Chances are, the resolution is set to 72 ppi.
The Document Size box shows how big a print you can make at the current resolution. As shown in Figure, I can make a 31" 23" print from this four-megapixel picture. Though that's technically true, it wouldn't look very good printed at 72 ppi. That's just not enough resolution.
The Image Size dialog box in Photoshop Elements
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