PC Alamode
Reviews Columns Features Archives

 PC Alamode

Benefits of adding a scanner to your system

Clarke Bird, is a short-timer as he will be retiring as editor of this publication with the November issue.

Adding a scanner to your system can greatly enhance your enjoyment of computing. With scanner prices drifting down to the $100-$200 range, scanners are now very affordable. Yes, there are some scanners even less expensive but it has been my experience, a scanner priced at less than $100 will not offer you the long-term use that a slightly more expensive scanner will offer. In this article, I'm going to focus on flatbed scanners although there are multi-function printers that also feature scanning capabilities and there are wand scanners in which you pass a wand over an image or printed page to digitize the object.

First of all, a scanner is a hardware device that captures an image and converts it into a digital format that your computer can then display, edit, store, and output. Most scanners come bundled with a image enhancement software package - frequently a "light" or stripped- down version of a popular brand.

The image to be scanned can be almost anything - from traditional objects for scanning such as photographs, pages of text, drawings or illustrations, to even relatively flat three-dimensional objects like coins, leaves, a swatch of fabric with an interesting pattern.

You initiate the scanning process within your image enhancement software program. I use both Photoshop and Photo-Paint but ArcSoft's PhotoStudio, PaintShop Pro or any one of dozens of similar, but less expensive image enhancement software programs will do the job for you. To start the scanning process, you click on File, Import and a list of hardware capture devices that are installed on your PC is shown. Click on your scanner name and you're off to the races. At this point, you may be offered the opportunity, depending upon the software, to increase or decrease the resolution you will obtain from the scan. The image is scanned and immediately "imported" into your photo enhancement program. This is where you will "Save As" to give the image a filename and file it in a folder you select.

Enhancing scanned image
When the image is imported into your image-editing software, you can then edit, manipulate or enhance the scanned image, using the tools and features of the editing software for this purpose. For instance, you can use your image-editing software to correct the brightness and contrast settings of the image, adjust histogram levels, or apply filters to create special effects.

What kind of scanner do you need?
The type of scanner you need really depends on the kind of work you will be doing with it. For example, if you want to capture images to place into your Web page, a company newsletter, or a school project, consider 24bit color flatbed scanners with 300 x 600 dpi optical resolution.

If you want to scan images to appear in 4-color offset printing, you may need a 30-bit or 36-bit color scanner featuring at least 600-dpi optical resolution. The increased bit depth enables these scanners to deliver images with more detail and more overall tones of color.

Finally, if you need to capture 35mm images from slides or filmstrips for publication, Web sites, or multimedia presentations; or want to archive your collection of 35mm slides, consider a 35mm slide and filmstrip scanner.

Scanners capture images or text for a wide range of applications. Other than a digital camera, a scanner is the quickest way to get pictures into your computer and then onto a disk, a CD, a printed page, or sent electronically to a friend across town or on the other side of the world.

Now grandparents can transfer all of their grandkids' artwork from the refrigerator door into their PC as wallpaper or screensavers.

For a home business, a color scanner is now a necessary business tool. It's the perfect device not only for copying and archiving important documents but also for capturing images to promote and market your business.

Many scanners offer software that mimics a conventional photocopier where you can lighten or darken an image to be copied (scanned), dial in the number of copies you want, or resize the image to be copied.

What can do with a scanner ?
Scanners can be used to capture just about any type of image for an endless number of applications.

  • Students use scanners to capture images to illustrate term papers or special projects, to make announcements for school or team sports events, to capture images for school newspapers and yearbooks.
  • Business people use scanners to capture images that they can use in presentations, reports, company newsletters, and brochures. Real estate agents use scanners to capture images of homes for ads and fliers.
  • Parents use scanners to capture and save their children's artwork; kids scan found items, coins, postage stamps, their favorite rock stars from magazines; parents can scan old family photos to make a digital family tree or family album.
  • Newlyweds scan their wedding photos to create a multimedia presentation of their wedding.
  • And scanners are used on a daily basis by graphic designers, photographers and other professionals to capture images for advertising, Web sites, magazines, brochures, packaging and much more. Scanners are even being used to digitally preserve valuable documents and manuscripts before they disintegrate.

    How do scanners work?
    To convert an image to digital information, scanners shine light on the image to be scanned. The light then bounces back and is captured by a strip of light-sensitive cells called a charge-coupled device, or CCD.

    Since dark areas reflect less light and light areas reflect more light, the CCD is able to detect the amount of light reflecting from the different parts of the image being scanned. The CCD then converts the reflected light waves to digital information. Finally, the scanning software that controls the operation of the scanner reads this incoming data and reconstructs it into a computer image file.

    Color Scanning
    To capture color images, scanners use a process based on the RGB (Red, Green, Blue) color model, in which every color is composed of a varying amount of the three colors.

    In the RGB model, the absence of white light creates black, the complete saturation of light creates white (100% of red, green, and blue), and varying amounts of red, green, and blue create intermediate shades of gray.

    Digital scanning
    For a computer to represent image information in a digital format, the computer uses units of picture elements, or pixels. An image file, for instance, is simply a representation of hundreds, thousands, or even millions of pixels arranged in a grid, and computers record the intensity and color of a pixel in 1 or more bits of data. The greater the number of bits (or bit-depth) of an image, the more information it can store. For easy classification, images can be categorized into single-bit, grayscale, or color.

    Bit Depth & Image Quality
    The bit-depth of a scanner determines the sharpness of detail and the clarity of color in your images. A 36-bit scanner, for instance, can sample much more information than a 30-bit or 24-bit scanner, and the extra information processed by the 36-bit scanner translates to more vivid color reproduction, smoother color blends, and more subtle gradations of color approaching lifelike accuracy. A 36-bit scanner also has a greater dynamic range, giving you more visible detail especially in the critical shadow and highlight areas of an image.

    What resolution should you scan at?
    An important feature of a scanner is resolution, which is the amount of detail recorded by the scanner. Resolution is measured in dots per inch (dpi). The greater the dpi number, the higher the resolution.

    The resolution you select to scan should depend upon the final output. If it is a funny cartoon or photo you want to e-mail to a buddy to read/see on his/her monitor, then 72dpi will suffice. Saving it to a JPG file will allow your buddy to see the image immediately upon opening your e-mail message. If you save as a TIF file, the recipient will have to use an image enhancement program to view the graphic.

    If you are scanning something for printing, then 300dpi should be the mininum scan resolution.

    It's important to distinguish between optical or true -resolution, and interpolated resolution which is resolution enhanced through software. Optical resolution is the amount of information that a scanner's optics can sample or "see" as the CCD moves vertically across the image. A 24-bit scanner, for example, typically has an optical resolution of 300 x 600 dpi, while 30-bit or 36-bit scanners typically have optical resolutions of at least 600 x 1200 dpi.

    Interpolated resolution is accomplished in software by surrounding pixels already seen by the scanner with new pixels that are mathematical averages of the original pixels. Interpolation can be helpful when enlarging images to retain clarity, or when scanning black-and-white images or fine line art to produce smoother lines.

    Scanning a page of text
    One of my favorite uses of my scanner is Optical Character Recognition (OCR) which eliminates the necessity of having to retype a document.

    Text scanning is done through the use of OCR software, which is able to recognize the shapes, shades and lines that make up individual characters in a text. When the text recognition process is complete, the user can save the OCR-processed file in various word-processing formats. The document is then ready for editing. I use OmniPage Pro for OCRing documents. Frequently I OCR several pages at a time and OmniPage Pro then attempts to edit the scanned document for individual letter interpretation errors (which sometimes happens) but I prefer to go ahead and save the scanned document directly into WordPerfect where I edit the document - Spell Checker will find anything unusual in the document..

    OCR accuracy is measured in terms of accurately identified characters, and a 99% accuracy rate means that 99 out of 100 characters are identified correctly. Accuracy is dependent, however, on the original document being scanned. For instance, a typed document yields much better OCR results than a faxed document or one that's heavily smudged.

    If you don't have a scanner, I recommend you go to your office supply store, Best Buy or CompUSA to look at a broad selection and price range. I assure you that you will find it an extremely useful tool.

    Scanning Process diagram

    Copyright© 1996-2010
    Alamo PC Organization, Inc.
    San Antonio, TX USA