Scanners are remarkably versatile devices. With a scanner you can create image files from photos, newspaper clippings, books, business cards, documents of all kinds. You can convert documents to editable text. You can link up a scanner with a printer and, voilà, you have a photocopier.

While the ins and outs of scanning can become quite esoteric, the basics of scanning good looking images are remarkably easy.

Setup

Your scanner comes with software drivers to make it work with Windows, including a TWAIN driver. Most image editing software supports the TWAIN standard.

geekgirl.technote: TWAIN?

TWAIN, in what is almost a first for the computer industry, is not an acronym. Instead, it comes from the saying "Ne're the twain shall meet", used in this instance to indicate the difficulty (at the time the standard was developed) of trying to connect computers and scanners.

You can use the supplied software to transfer images from your scanner to your computer, but most people load up their favourite graphics/photo editor and scan directly from there. Look for an option called Acquire, usually on the File Menu. You may need to dig around a little to find it. For instance, in Paint Shop Pro you need to select File -> Import -> TWAIN -> Acquire. The first time you use your scanner via your graphics program, you will need to select it as the TWAIN source (in Paint Shop Pro, it's File -> Import -> TWAIN -> Select Source).

geekgirl.tip: close other apps
Before you start scanning, close down all applications apart from the graphics/TWAIN program. Scanning is highly system intensive, so there's no point in having other programs open, and doing so will reduce the resources available for scanning.

Select your scanner as the source before acquiring the image

Before you can use your scanner with your graphics program, you must select it as the source and then use the Acquire image function to perform the scan.

Pre-scan

When you're ready to scan, place your original photo or document face down on the scanner. Alignment marks around the edge let you adjust its position, but you don't need to worry too much about that as the TWAIN software will let you adjust this. Do, however, make sure you square the original so it scans straight.

Once the original is ready, click the Prescan/Preview button in the TWAIN application. This creates a low-resolution, quick scan of your image which lets you see how it will look.

geekgirl.technote: OCR

If you wish to scan documents so you can edit the text, you'll need OCR (Optical Character Recognition) software. Instead of producing an image of the document, as traditional scanning does, OCR reads the actual text and lets you convert it into a word processing file. One of the best value OCR programs is Presto OCR from Newsoft. You can also get a good deal on OmniPage Pro from ScanSoft.

Adjustments

Take a look at the pre-scanned image. If your image occupies only a part of the page, or if you wish to scan only a portion of the image, use the sizing box to reduce the area to be scanned to the exact proportions. This greatly reduces the size of the scanned image, reduces the time it takes to perform the scan, and reduces the RAM required. It also means less editing for you later.

Adjust resolution and other settings before scanning.

Before performing the final scan, select the correct image type, adjust the resolution (note the size of this image at 300dpi will be 22.11 megabytes) and use the selection rectangle to chose which part of the image to scan. (Click the image to see a full-sized screenshot.)

Each TWAIN application offers different controls, but all of them let you adjust the resolution (DPI, dots per inch), size and type of scan.

Select the scanning mode according to the type of document you're scanning: colour or black-and-white, photo or document, line art, and so on.

Which resolution you choose depends on what you want to do with your scan. Below are some guidelines. If you'd like the full scoop on resolution, visit Scantips.

Keep in mind high-resolution images occupy a lot of space both in RAM and on disk. If either of those commodities are limited, lower the resolutions you use.

Once you've made these adjustments (most other settings you can leave at their defaults), click the Scan button to scan your image.

The scanned image

Once scanned, close the TWAIN application and your image will be available in your graphics program for editing. Trying to manipulate the image in RAM is a slow process, so the first thing you should do is save the image. For professional purposes TIFF format is commonly used, but for most users JPG format is best. Use minimum compression – you'll still reduce the file size while retaining quality.

If you find your graphics program is responding sluggishly when you try to edit the scanned image, first try closing the program down (after you've saved the image, of course) and then reopening it. If the program asks whether you wish to save information on the Clipboard, say no to release this memory as well. Then reload the graphics program and open the image for editing once more.

If your program is still sluggish, it may be because the image is so large. If you scan in 300dpi or greater, you'll end up with a very sizeable image which will eat up RAM as you work. Just be patient.

A moire pattern created by scanning an image from printed material.

A moiré pattern created by scanning an image from printed material. (Click the image to see a full-sized screenshot.)

The most common editing tasks you'll need to perform on the scanned image are rotating it and removing the moiré pattern. Moiré is a grid-like pattern which appears when you scan images from printed materials. The printed materials use a halftone screen printing process which looks fine in a glossy magazine but which produces an interference pattern when scanned onto your computer. If your TWAIN driver has a descreen filter, using it during the scanning process should help minimise the moiré pattern. Otherwise you can use tools in your graphics editing software to remove the pattern. Paint Shop Pro, for example, has a moiré pattern removal option (click Effects Menu -> Enhance Photo -> Moiré Pattern Removal).

Use your graphics program's editing options to enhance your scans.

Use your graphics program's editing options to enhance your scans, including removing moiré patterns.

© 2003,  Rose Vines

Support geekgirl's

Do you find the tutorials on this site useful? If so, please show your support by kicking in a few bucks to sponsor an orphanage for Afghan refugees. For a small amount, it is possible to make a difference in an area of the world which is hurting badly.

Want to know more? Read this post on my blog.
top home basic computing