Scanning Secrets
Use these scanning secrets to avoid some common mistakes.
Mastering the ancient art of scanning documents and images
isn't as challenging as you think. Here, we’ll show you how to scan oversized
documents and stitch them back together.
If you have any questions about scanning, here are some answers. Read through
these scanning tips and tricks that aren't discussed in user manuals.
Matching the resolution of your input and output devices is
a fundamental digital-imaging skill. Think about it: Why scan an image at
600dpi if your ink-jet printer can't produce images any clearer than 200dpi?
Your resulting print won't be true to the original image -- it will be much
bigger and might not even fit on your printer paper.
Sometimes, though, you want to increase the size of an image through the scan
and print process. For example, if you want to scan a small image (say a 3-inch
by 5-inch photo) in order to have it exit the printer twice as big, you need to
do some simple math to figure out what resolution to scan at.
If you want the intended and original image sizes to stay the same, or if you
want to increase the intended image size, here's the equation to keep in mind:
Resolution to scan at = printer dpi x
(intended image width / original image width)
Let's say that our printer dpi is 200 and we want to make a 6-inch by 10-inch
image out of a 3-inch by 5-inch photograph.
The math:
200 x (6/3) = 400dpi
Thus, we'd want to scan the image at 400dpi to get the intended result.
Your computer monitor is also an output device. Generally, if your scanned
images aren't going any farther than a webpage or an electronic photo album,
there's no need to scan at more than 75dpi.
By keeping the resolution lower, you'll save a lot of hard-disk space.
Furthermore, it'll take far less time for the scanner to capture the image,
anyone looking at the image on your website won't be able to tell whether you
scanned it at 75dpi or 600dpi, and if you intend to email the image to a
friend, it'll move across the Internet much more efficiently at 75dpi.
When scanning images, resolution isn't the only thing to
consider. You must also consider what file format you'll use to save the image.
If you have a monstrous hard drive and want pristine quality, save the image as
a bitmap.
A bitmap is an uncompressed file format, meaning it will consume a great deal
of disk space. (An 8-inch by 10-inch photo scanned at 24-bit color at 600dpi
will consume 84.4MB of disk space -- nearly the size of a whole Zip disk.)
Bitmaps are good, though, because there's no loss in image quality.
Generally, though, save your images as TIFF files. TIFF is a
"lossless" compression format, meaning you won't lose any detail
despite massive file size shrinkage. What's more, TIFF images can be exported
into most graphics, layout, and word processing programs.
For websites, save your images as 72dpi JPEGs. Though you'll give up image
quality, JPEG files are drastically compressed. Small file size is a tremendous
boon if your ISP offers you 20MB of space for your website.
Ever see photos of living people that appear to be from the
late 1800s? They probably paid $50 to get that photo taken at an amusement
park. You can do it on your scanner for free. Turning a vibrant color photo
into a sepia-toned, old-looking image is easy.
First, scan the photo as normal. Then, using your image editing software, crank
up the Noise Filter to give the photo a dirty, grainy look. You can then
convert the photo to grayscale or just monkey with the contrast a little. The
next step is to colorize the image with a hue of about 30 and a saturation of
50.
Finally, blur or soften the image to make it look like it was taken by an old,
imprecise camera. Mount it in an oval frame and you've got a fake family
heirloom. Some image editing software packages, such as Adobe PhotoShop
Elements, have built-in tools for making new pictures look old.
You can also do the opposite. Let's say you stumble across a photo of your
great-grandmother taken in the 19th century. The thing is falling apart, and
you want to preserve the image before it crumbles into dust. You can scan it
and use editing software to erase all the scratches and holes and also correct
color inconsistencies.
The best method is to clone an intact piece of the photo and then use its color
value to paint over a ruined spot. Many image-editing programs can guide you
through the process or you can tinker with the image on your own. Make a copy
of the original file so if you mess up, you don't have to scan the image again.
Go 3-D
There's no law saying you can only scan flat things such as
photographs and magazine articles. Be creative: You'd be surprised at what
scans wonderfully and how many things you can do with the unorthodox resulting
images.
For example, 3D objects are fair game when it comes to today's flatbed
scanners. Put the object -- jewelry, food, cats, things you've found in the
woods -- on the glass platen and rest the scanner lid upon it. When the scanned
image appears in your image-editing software's viewing area, you'll be shocked
at the quality.
No one has a copyright on things you've found in the woods. That means you can
use those images on your website with no fear of infringing on anyone's
copyright. In the case of food -- and food scans beautifully -- be sure not to
leave any greasy residue on the glass platen. A little spurt of window cleaner
and a clean, lint-free cloth or a specialized lens-cleaning pad will do the
trick.
You should also think about scanning unorthodox objects to use as backgrounds
for your WebPages. For example, go outside and find yourself some beautifully
colored leaves. Lay them on your scanner so that you can't see the glass plate
at all. Execute the scan. Use the resulting image as a webpage background.
Magazines, newspapers, and books present the perfect
material for scanning images. But, in order to get the best results from your
scanner, you need to understand how images are manipulated so they print
correctly using a printing press.
When you send an image to a printer, the printer must create what's called a halftone before it's
printable. A halftone turns a regular image into a system of dotted and
checkered spots that are usually invisible to your eye. These dots and checkers
simulate gradation of tone values and make it possible for the image to be
printed on a press.
When you scan a printed image you must be aware that these dots and checkers
exist. Your scanning software should contain a setting that will allow you to
scan images from printed material. This means the scanning software will remove
the dots and checkers so they don't appear on your final scan. Now you know why
your scanned images always come out looking dotted and checkered. Since all
scanning software's a little different, consult your manual to find out how to
correct this problem.
Automatic stitch
If you'd like to scan a map and stitch the scanned images into a complete
document again.
Most scanners only let you scan documents or images up to 8.5 inches by 11
inches. The standard scanner may not cover enough area if you need to scan
newspapers, maps, oversized magazines, or oversized books. If you find yourself
in
Image stitching involves importing smaller scans into a graphics program to
create a single document. Any program used to create a panoramic photo can be
used to automatically reassemble scans.
Here are a few popular image-stitching programs:
Manual stitch
If you find that a panoramic photo maker doesn't allow precise enough stitching
control, then you're going to have to manually do it with a standard
image-editing program. Numerous programs will re-create an oversized document
from smaller scans.
Here's a list of popular programs that let you manually stitch:
Another option is to use PowerPoint or Word. These two programs offer crude image-manipulation features. If you don't plan on digitally re-creating the Declaration of Independence, one of these two may do the job nicely.
You'll be barraged with
choices at your local computer store. I like traditional flatbed scanners the
best. They're easy to use and let you scan 3D objects in addition to magazine
articles, photos, and other 2D objects. Items you're scanning will stay still
during the scanning process, so errors are less likely.
You can get a good flatbed scanner for between $60 and $100. A good source for
scanner deals is Price Watch. The only
real problem with flatbed scanners is that they take up a whole lot of desk
space.
If office real estate is at a premium, you might want to consider buying a
sheet-fed scanner. They're about as big as a quarter-full roll of paper towels.
To work one, you slide a photo or article through the input slot. Though they
cost about the same as flatbed scanners, forget about scanning anything but 2D
objects.
You can also get a handheld scanner. You operate one by dragging it across a
flat surface as if you were ironing clothes. It's difficult to get good images
with handheld scanners because you often have to make more than one pass across
a document to capture the whole thing. But for folks who often take their
business on the road, handheld scanners are the only choice.
No matter what the shape, make sure the scanner you buy has a CCD (charged
coupled device) rather than a CIS (contact image sensor). CCDs
and CISs are what capture images. As its name
implies, a CIS needs to contact the image for everything to work properly.
There will always be a piece
of glass between the CIS and the image to be scanned, necessarily degrading
scan quality. CCDs capture light waves bouncing off
the image to be scanned, meaning the clear glass platen doesn't act as an
obstruction. Unlike CIS scanners, CCD models let you scan 3D and textured
objects.
Finally, think about what interface you want. Parallel port scanners are easy
to set up, but data travels through parallel ports relatively slowly. SCSI
scanners are fast but difficult to set up, so unless you enjoy wrestling with
your computer you should avoid them.
It's best to go with USB scanners. All you need do is insert a plug into the
back of your machine. This is great if you like to store your scanner in the
closet when you're not using it. What's more, USB transfers data quickly.
Additionally, you may want to consider getting a FireWire scanner. FireWire
scanners transfer scanned images almost 40 times faster than do USB scanners.
You should be able to find a decent FireWire scanner that also includes a
FireWire card for under $125.