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Crop your pictures BEFORE you do the final scan, using the scanner's preview mode.
  technofile
Al Fasoldt's reviews and commentaries, continuously available online since 1983

T e c h n o f i l e
Image is everything, Part 1: Scanning tips for beginners (and maybe old pros, too)


Jan. 5, 2003


By Al Fasoldt
Copyright © 2003, Al Fasoldt
Copyright © 2003, The Post-Standard

   When I looked through my list of requested column topics last week, I discovered that a lot of you want more information on scanning images and on other digital-photo topics. This week I'm offering the first installment of a three-part mini-series on digital image techniques.
   This week, 10 tips for scanning on Windows and Mac OS X computers.
   1. PRACTICE. Scanning is not a God-given ability. Get used to how your scanner works by scanning both large and small photos, magazine covers and (in the case of slide and negative scanners) slides and film strips. Practice every chance you get.
   2. NO SLIDES ON THE FLATBED. Flatbed scanners, which have lift-up lids for scanning large, flat objects, do an inherently bad job of scanning tiny slides and negatives. They're just not made for that kind of work. No matter how much your neighbor or brother-in-law tells you otherwise, flatbed scanners should not be used for scanning slides and negatives. Get a slide and negative scanner instead. Prices start well below $200.
   3. IT'S ALL A BUNCH OF CROP. Always, always always -- did I mention the word "always"? -- crop your pictures BEFORE you do the final scan, using the scanner's preview mode. After the quick preview shows up on your screen, crop the image by drawing a box around the area you want scanned. Never scan the white background along with the photo. Three good reasons: The scanner's automatic brightness and contrast adjustment will think the white background is part of the picture and will adjust the image quality badly; the image will be much bigger than it has to be, making the resulting file unwieldy, and the scan will take a lot longer.
   4. DOTS RIGHT. Never scan at the highest resolution (dots per inch) just because it has a higher number. Nearly all scanners have a "fake" high-resolution setting that is interpolated (created by fancy guesswork) out of the scanner's optical resolution. Use the lower number if the scanner has two different resolution numbers, such as 1200 by 4800. In such a case, "1200" is the optical resolution and "4800" is the interpolated one.
   Then what resolution should you use?
   Flatbed scanners: If you're scanning for a Web page and will never use the scan for anything else, scan at 75 to 100 dpi. If you are scanning for a photo-quality print, scan at 300 or 600 dpi. If you are scanning for archival purposes (to have a copy of an important item, for example), scan at the highest optical resolution your scanner can manage.
   Slide and film scanners: Scan at the maximum optical resolution of the scanner. If you're not sure what the max resolution is, write to the company that makes the scanner or look in the manual or help menu. Often, the optical resolution will be part of the model name, as in the PrimeFilm 1800u scanner; it's the one I recommend, and scans at -- guess what? -- 1800 dpi. (The "u" stands for United States.)
   5. NO JPEGS. JPEGs (also called JPGs, and pronounced "jay-pegs" in both cases) are images that have been stripped of some of their detail in order to make them smaller. They're fine for some purposes but are totally wrong for scanning. Do not save your scanned images as JPEGs. Save small scans as BMPs if you use Windows, or TIFFs if you use a Mac; save large ones as compressed TIFFs on Windows or Macs. (They're also called TIFs and pronounced "tiffs" in both cases.) Or save everything as PNGs ("pings"). Never save them as JPEGs. Once you create a JPEG, you can't get the quality back; it's thrown away. Don't do it.
   6. ORIGINALS ARE PRICELESS. Never do anything dumb with the original scans. Save them exactly the way they were scanned, without any changes. In other words, when you make each scan, make a copy that you can edit (to rotate, crop, brighten and so on), then save the original scan and store your originals on CD. "Original" means the exact scanned image, before anything has been done to it -- before it is rotated, too. (Rotation sometimes alters the image in ways that can't be fixed.) Don't forget to save your edited scans, too, after you're through.
   7. GET WITH IT. Get a good image editor. Don't assume that the piece of dreck software that came with your scanner is any good; it probably isn't. Get Adobe Photoshop Elements (version 2.0 or higher), whether you have Windows or a Mac (the same installation CD has both versions).
   8. SAM NEVER KNEW. Scanners usually have a "twain" module that lets your scanned images appear inside an image-editing program. It's usually a dumb idea because it encourages you to use the scanned original instead of saving it and using a copy. (See Tip No. 6.) Even the term "twain" is bozo. It means "Technology Without an Interesting Name."
   9. CLEANLINESS IS NEXT TO IMPOSSIBLE. Keep the scanner's glass as clean as you can, using Windex or a competing glass cleaner. I clean mine before every scan.
   10. SCREEN TEST. If you haven't calibrated your monitor so that images are faithful in the five important ways -- white level, black level, gamma, color saturation and color tint -- you KNOW you can't trust what you see on the screen. Set aside an hour or two next week to do some serious adjustment.
   Next: Getting your monitor to tell you the truth about your images.