Showing Resolve

By M. David Stone  |  Posted 2008-02-08 Print this article Print


Optical and Mechanical Resolution

Optical resolution tells you how many pixels the scan element can see at once across the width of a page. Mechanical resolution tells you how many steps the scan element takes going down the page (or how many the page takes going past the scan element). A spec like "600-by1,200-dpi optical" really means "600-ppi optical by 1,200-ppi mechanical."

N by M Optical Resolution. Not.

Even ignoring the distinction between optical and mechanical resolution, a spec such as "600-by-1,200 optical resolution" is misleading. The scanner can't pass a 600-by-1,200-ppi image to your computer, so the top resolution you'll get without interpolation is 600-by-600 ppi.

Interpolated Resolution

Scanner manufacturers like big numbers, such as "19,200-ppi interpolated resolution." Whatever the interpolated resolution, this is a good spec to ignore. You can get results that are just as good or better (particularly for photos) by doing the interpolation in separate steps in Photoshop or other software.

High Optical Resolutions

Even high optical resolutions usually don't matter. For typical office tasks such as copying, faxing and scanning to PDF files, and even for scanning photos to print at the same size, a 600-ppi scanner is almost always all you need. Higher resolutions are rarely useful unless you're scanning, say, slides or otherwise need to resize the image.


M. David Stone is an award-winning freelance writer and computer industry consultant with special areas of expertise in imaging technologies (including printers, monitors, large-screen displays, projectors, scanners, and digital cameras), storage (both magnetic and optical), and word processing. His 25 years of experience in writing about science and technology includes a nearly 20-year concentration on PC hardware and software. He also has a proven track record of making technical issues easy for non-technical readers to understand, while holding the interest of more knowledgeable readers. Writing credits include eight computer-related books, major contributions to four others, and more than 2,000 articles in national and worldwide computer and general interest publications. His two most recent books are The Underground Guide to Color Printers (Addison-Wesley, 1996) and Troubleshooting Your PC, (Microsoft Press, 2000, with co-author Alfred Poor).

Much of David's current writing is for PC Magazine, where he has been a frequent contributor since 1983 and a contributing editor since 1987. His work includes feature articles, special projects, reviews, and both hardware and software solutions for PC Magazine's Solutions columns. He also contributes to other magazines, including Wired. As Computers Editor at Science Digest from 1984 until the magazine stopped publication, he wrote both a monthly column and additional articles. His newspaper column on computers appeared in the Newark Star Ledger from 1995 through 1997.

Non-computer-related work includes the Project Data Book for NASA's Upper Atmosphere Research Satellite (written for GE's Astro-Space Division), and magazine articles and AV productions on subjects ranging from cosmology to ape language experiments. David also develops and writes testing scripts for leading computer magazines, including PC Magazine's PC Labs. His scripts have covered a wide range of subjects, including computers, scanners, printers, modems, word processors, fax modems, and communications software. He lives just outside of New York City, and considers himself a New Yorker at heart.


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