Figure 1                                              Figure 2                                                        Figure  3        

 SCANNING IT!
 

Ever since the Internet became available to consumers through the World Wide Web, people have tried to sell items through it. You've stormed e-bay and other auction sites with gusto. However, the underlying concept of selling online is a visual one to see it is to buy it. Therefore, you had to find a convenient way to display photographs of your items. While scanners are the right tool, most people don't know how to scan correctly.

A scanner lets you input any kind of image into your computer, but it can quickly eat up your system's memory and hard disk space. Because today's scanners offer higher resolutions and more colors than ever before, they're capable of producing huge files that quickly gobble up your disk space.

Scanning the Photo
When you scan a photo (Figure 1), you create an image file. The amount of space the file takes up on your hard disk is directly related to both the size and complexity of the photo and the resolution you use when you scan it (Figure2). Resolution is measured in dots per square inch (dpi). For example, doubling both the horizontal and vertical resolution going from 300 by 300 dpi to 600 by 600 dpi quadruples the size of the image file. Also, the higher the resolution, the longer it takes to scan the photo.

Once you scan a photo (Figure 3), you can change the resolution by clicking on the FORMAT menu and then on RESOLUTION, followed by clicking on the USER DEFINED dot. You can then change the resolution of your scan by clicking on the arrows in the box next to User Defined. Change the resolution to 75 dpi and save your image. This not only saves disk space but also saves time when moving the image over the Internet. Though more always seems like a better idea, when you scan a photo more dots aren't necessarily a good thing.

Every image consists of thousands of dots called pixels. Increased enlargement beyond what makes the pixels visible cannot show additional detail. It only makes the pixels appear larger. So scan resolution merely determines image size. When you increase scan resolution, it increases the image size. A 6x4-inch photo scanned at 110 dpi almost fills a 640x480 monitor screen, the typical monitor resolution used by most users.

Eliminating Moiré Patterns
Scanning at high resolution is one way to eliminate Moiré patterns, those wavy lines found when scanning images from printed material books, magazines, newspapers, and postcards. Except for a few special purposes, and except for Line art, a resolution of more than 200 dpi can be pointless.

Large images also consume memory. Memory for an image is computed from the image size. For a 6x4-inch image at 150 dpi, the image size is calculated as:

(6 in. x 150 dpi) x (4 in. x 150 dpi) = 900 x 600 pixels
the memory is: 900 x 600 x 3 = 1.6 million bytes.

The last "x 3" is for 3 bytes of RGB  (red, green, blue) color information per pixel for 24-bit color.  An 8-bit Gray Scale is one byte per pixel, and Line art is 1/8 byte per pixel. When you double the scan resolution, memory increases four times. To reduce file size, reduce resolution. So by reducing your resolution to 75 dpi after you scan you save four times the memory.

Saving Your File
You can also minimize if you save images in a compressed file format. When you save a file, your image software lets you designate the file type. TIFF and GIF files (identified by the .tif and .gif extensions, respectively) are file types that use "lossless" compression technology that is, when you open one of these files, the image is identical to the original image. JPEG is a "lossy" format, because an image loses some detail when you save it.

Use TIFF for any image you plan to print. You get disk-space savings without any loss of detail. Use JPEG for any file you use online, either in E-mail or on your Web site. JPEG results in smaller files that are easy to transmit. And because you view them on-screen, they don't need the detail a printed file requires. File compression doesn't mean you should ignore resolution amounts,  but it will make it possible to store more image files on your hard disk.

TIFF is the best format for black-and-white or gray-scale scans. Artwork scanned as TIFF (Tagged Image File Format) can be immediately placed, copied, resized and so on. But TIFF files are large and printing can be slow. The size of any Web page with several TIFF files placed in it can balloon into megabytes.

Though scanners come in many shapes and sizes, flatbed scanners remain the most versatile because they can scan pages from books and magazines in addition to single photos. While a 300 dpi scanner will do just fine, 600 dpi scanners are generally more fully featured. You'll probably have few occasions to scan color photos over 200 dpi, and a 600x1200 dpi, 36-bit scanner like those on the market for under $100 are a real bargain and capable of delivering great results.

Imaging Software
Don't minimize the importance of your scanner software. Software varies considerably among scanner brands. Microtek's ScanWizard is excellent. Frankly, in scanning, as in photography, user skill and attention makes a greater difference than the equipment. While the original photo quality is important, the tools do count. Most scanners come with some software.

As for imaging software, Adobe Photoshop is definitely the best. But you can get along just fine with Ulead PhotoImpact (Ulead Systems, Inc.) and for much less money. To organize your images, use Thumbs Plus (Cerious Software).

Finally, don't be afraid to experiment with different resolution and color settings. Each scanner-printer combination is different, so you should test yours to see what scanner settings work best for you. The more you know, the better you can take advantage of imaging on your computer.