Monday, October 25, 1999

Scanner features more important than price

KIM KOMANDO

Kim Komando's Komputer Klinic

Scanners are simple, right? You ,plug 'em in, toss a picture onto the glass, push a button and BAM! - just like that you have a dynamite looking digital representation of your autographed picture of Pamela Lee Anderson.

Well, if you spent more than 10 minutes looking into the wonderfull world of scanning, you know it's not quite as easy as it looks.

Scanners are confusing even before you buy one. Is the $600 scanner really 10 times better than the $60 scanner? Should I spend extra to get a 36-bit scanner, or should I settle for a 32-bit econo-job? All good questions.

My main rule of scanner shopping is: Buy the cheapest scanner you can find that has the features you want. This statement will probably ruffle the feathers of a few raphic arts purists, but think think about it. -You're not a professional designer, are you? Your life doesn't depend on whether the shade of green in the photo is the exact same shade of green that appears on your monitor, does it? For the average Joe or Jane (or Kim), an inexpensive scanner will fill the bill quite nicely.

However, note that I did say you should look for the features you want. The fact is, the absolute cheapest scanner you find may not have all the features you want.

For starters, let's get back to this bit-depth thing - the 32 bits vs. the 36 bits., The bit-depth capabilities of a scanner refer to how much color information it can pack into a single scan. In other words, how many distinct colors can the scanner recognize? Here, 32 bits should do the average home user just fine. In fact, it wasn't so long ago that 24-bit color was considered high-end, photorealistic scanning.

Even with the best monitor and video card, you can only see 32-bit color on your computer screen. That means even if you scan at 36 bits, the image won't look any better on your screen than a 32-bit image. It's one of those lowest common denominator things.

What's more, the higher the bit depth, the more room the image will take upon your hard drive. A 36-bit image will take up about 13 percent more than a 32-bit image. That may not seem like much, but if you scan a couple of hundred large images, you'll see that precious disk space disappear in a hurry.

What about resolution? Do you need 600 dpi (dots per inch) or will 300 dpi do the trick? And what's this stuff about optical resolution vs. interpolated resolution? First off, optical resolution is the scanner's real resolution. Most scanners come with special software that can guess at what the image should look like and fills in the blanks to produce a higher resolution than what the scanner can handle on its own. That's called interpolated resolution. As you can imagine, optical resolution produces better results than interpolated resolution.

That means you should get a scanner with the highest possible optical resolution, right? Well, not necessarily. In fact, in most cases, you should never have to scan a photo at more than 200 dpi or so. You might think that since you have this awesome ink-jet printer that can spit out digital photos at 1,400 dpi, it only makes, sense that you should try to scan at 1,400 dpi. Wrong.

You see, comparing the dpi on your scanner to the dpi on your printer is like comparing apples and oranges. When your scanner scans 11 a dot," that dot can be any one of millions of different colors. However, when your typical ink-jet printer prints a dot, it only has four colors of ink to choose from.

I won't dwell on the mathematical details, but the situation is clear. To produce that one color from that one dot from your scanned image, your printer actually uses a whole bunch of different colored dots. By combining dots from its four colors of ink in just the right way, your printer fools your eye into thinking it really sees the right colors.

If you don't believe me, just conduct this simple experiment. Scan the same picture at several different resolutions - say, for example, 100 dot, 200 dpi and 300 dpi. Then print

each one out on your color printer using the, exact same printer settings. Finally, see if you can tell them apart. Depending on your printer, the 100-dpi image may be inferior, but I bet you can't tell the difference between the other two.

The reason this is important is because higher resolutions translate to bigger file size on your hard drive and more work for your computer and software. You're just wasting resources if you scan a picture at a higher resolution than you really need it.

Here's a final thought on scanning resolution. Believe it or not, your monitor displays images at only 72 dpi That means if you're scanning a picture that will never be printed - say a photo for your Web page - you only need to scan it at 72 dpi That'll save plenty of room on your hard drive, and if you are creating a Web page, it'll save your users download time, too.

Kim Komando is a nationally syndicated talk radio host, computer editor of Popular Mechanics and author. Visit Kim on the Internet at www.komando.com or send email to komando@komando.com . You can listen to Kim Sundays, Noon to 2 p.m. on 910 KFYI AM.

the webmaster notes here that one important thing in the cost of scanners just as in cameras is the GLASS or LENSES. the more light your lenses let thru the better the photograph or the scan. and a big huge lense will always let more light thru then a smaller lense. and big lenses cost more then smaller lenses.

so if you want high quality scans buy a scanner with the best optical lenses possible.