Although the specifics of getting the best results from your scanner
vary depending on what hardware you're using, there are a few general tips
that can help you out. Let's explore these tips, shall we?
Most scanning software lets you select the mode. Adjust the mode
depending on what type of image you're scanning. The most typical modes are
line art, halftone, grayscale, and color.
Line art is for things that contain solid areas of black and white. You
use this mode if you are scanning a black-and-white logo off your
letterhead or a pen-and-ink drawing. The key to this mode is that it
doesn't read any shades of gray.
Halftones are pictures from books, newspapers, and magazines. When
pictures are printed in newspapers, the continuous tones of the photographs
need to be converted into tiny black dots of varying sizes. Pictures in
books and magazines are made up of dots too, only a lot smaller. In the
case of color pictures, the dots are yellow, black, magenta, or cyan, all
layered on top of each other to form the picture. Anyway, the halftone
setting is for
scanning these kinds of pictures.
To scan actual color or black-and-white photos, use the color and
grayscale modes.
After choosing a mode, load your object to be scanned into the scanner
face down on the glass, just like on a photocopy machine, and hit Prescan.
The scanner will take a quick pass of the image and display a rough version
on your screen. This gives you an idea of what the final product will look
like, but more important, it lets you specify which section of the image
you want to scan. Getting a high-quality scan can sometimes take forever,
so don't waste your time scanning the whole thing if you just want a piece
of it. Scanning the whole thing takes up a lot of computer memory; it's a
waste if you're going to crop the photo later on, anyway. So use a
selection tool to choose the area you want to scan.
Prints and the Resolution
OK. You've determined what kind of picture you're dealing with and
selected the area that you're going to scan. Now you need to tell your
computer what size and resolution you want. These two settings are related,
and most scanning software has a slider for both. Some software, however,
assumes you scan things in at screen resolution (72 dpi — dots, or
pixels, per
inch) and lets you change only the size of the picture at that resolution.
This resolution stuff is important if you're going to scan something in
and print it or if you're going to manipulate it in image-editing software.
But if it's just a picture of your cat for your Web page, all you need to
remember is to make the settings 72
dpi at 100%. This will
ensure that the picture is the same size on the screen as it is in your
hands.
If you want the picture half as big on the screen, select 72 dpi for the resolution and 50% for the scale. If you want the
picture to be twice as big, make the scale 200%. Or if you want to be really tricky, set the
resolution at 144 dpi and the scale
at 100%. Remember, scale and
resolution are linked. You can either double one or double the other; it
doesn't really matter which.
Finally, click on the Scan button and let 'er rip. Well, "rip" isn't
totally accurate, since it'll probably take forever to finish — it's
guaranteed to be much slower than a photocopier. And if you're scanning in
color, most machines need to take three passes: one for red, one for blue,
and one for green.
Now that you have your picture scanned in, all you need to do is save it
as a GIF or a JPEG and you're in business. Get to work, and try not to
break too many copyright laws.
Jim Frew is Webmonkey's Tonga bureau chief. He currently teaches Web design at the Royal School of Science in Nuku'alofa, and spends his free time playing jai alai and drinking iced mochas.
