CHOOSE THE BEST LARGE FORMAT SCANNERS FOR YOUR BUDGE
Scanning documents larger than 11"x17"? This guide will help you pick the best scanner for your need
Large format scanning is a very precise art form. You need a very accurate scanner. An inaccurate scan of a highly detailed schematic, construction blueprint, file patent or CAD drawing can cost millions.
Engineers need special raster to vector conversion software. This type of software converts the pixel-based scanned image to a format that can be read and edited by computer aided design (CAD) applications like AutoDesk's (San Rafael, CA 415-507-5000) AutoCAD. Graphics professionals who scan tabloid-size documents and full bleeds need high resolution. Their ability to demonstrate their work and earn a livelihood depends on the quality of their scanned images.
To satisfy the needs of this demanding market there is a small, but dedicated group of companies.
Agfa's (Wilmington, MA 508-658-0200) 11" x 17" scanner, the Horizon Ultra ($18,000) is aimed at the industrial graphic arts market. The Horizon Ultra is a three pass 36-bit scanner. Its resolution is 1,200 x 2,000 dpi. Coming in October is the AgfaScan T8000 scanner ($38,500). This scanner will feature 8,000 dpi and 48-bit color.
Scanners and digitizers from Altek (Silver Springs, MD 301-572-2555) are high-precision devices for engineers and non-technical users who need a high level of precision. A digitizer lets you manually scan images, usually line art. The Colorscan II ($34,500) provides 400 dpi optical resolution in 30-bit color. The Allscan ($14,000) is grayscale. A lower cost version ($20,000) of their color scanner should be available this Fall.
Bell & Howell (Arlington Heights, IL 847-675-7600) Copiscan series are high-volume production scanners capable of scanning up to 11" x 17" documents. The PS series scans documents up to 55" long. The FB scanners are large format flatbed scanners.
Howtek's (Hudson, NH 603-882-5200) Scanmaster series are at the top of the industry. The Scanmaster 2500 ($16,000) is a large flatbed scanner with a 13" x 18" scan area. The Scanmaster 6500 ($45,000) and 7500 ($53,000) are high-performance drum scanners. The drum has a scan area of 18" x 24".
Ideal Scanners and Systems (Rockville, MD 301-468-0123) is the US marketing representative of Contex (Allerod, Denmark 011-45-4814-1122). Their scanners are aimed at the engineering market. Monochrome scanners have resolutions between 400 and 1,800 dpi ($9,000-$20,000) and 24-bit color scanners 500 and 800 dpi ($20,000-$25,000).
Publishers' archives are another large format scanner application. Image Access' (Boca Raton, FL 561-995-8334) Bookeye ($13,500-$15,500) scans books and documents up to 17" x 22" at up to 20 pages per minute. The Bookeye scans books, engineering drawings, newspapers and other documents for long term archival storage. It's designed to be used like microfilm cameras. It uses the Fujitsu video interface.
Kodak (Rochester, NY 716-726-7260) makes a trio of large-format production scanners ($29,000-$89,000). The 5500 and 7500 have a 12" x 20" area. The 95 has a scan area of 12" x 30". They are all one bit volume scanners from 80 to 160 pages per minute. All require ISIS drivers.
Linotype-Hell (Hauppauge, NY 516-434-2000), long known for their drum scanners, have a line of fine flatbed scanners. The OPAL scanner is a large-format flatbed scanner, 12" x 17", aimed at high-end graphics shops. It has a large feature set and resolutions up to 800 x 1600 dpi.
Most large-format scanners are high end products costing at least a couple thousand dollars. Plustek (Sunnyvale, CA 408-745-7111) is releasing an entry-level scanner ($800) for the SOHO market in early September. It will have a parallel interface, 30-bit color and a 12" x 17" scan area.
Umax's (Fremont, CA 510-651-9488) Mirage II ($8,000) is an 11" x 17" flatbed scanner aimed at graphics professionals. It has a dual lens design. One lens gives 700 x 1400 dpi resolution of 11" x 17" scans. The second lens doubles the resolution on narrow scans, 6" x 17". The Mirage IISE ($3,700) is a simplified single lens version of the Mirage II for less than half the price.
When you think of scanning, you automatically have to think about Xerox (Rochester, NY 716-423-5090). The Xerox 7336 ($17,500) is a fast grayscale scanner for engineers. The DocuCS ($17,000) and DocuImage 620 ($12,000) are large-format high-volume document scanners for any purpose.
Why Is a 36-bit Scanner
Better Than a 24-bit Scanner?
A quick look at high-end scanners shows you that 36-bit color is the standard. As technology gets better, color resolution will increase to 42 or 48 bits.
The cost conscious ask: "Why go to the expense of extra bits when you're going to reduce your images to 24 bits when you edit them?" Because 36-bit scanners have more colors. This just one reason why 36-bit scanners are better.
In a 24-bit scanner each primary color has 256 levels (8 bits) of intensity. If you have an image composed mostly of reds, the scan quality is similar to a 256 gray scale scan. This may be adequate for the final printed image, but you'd probably want better quality originals.
More important than the number of available colors is the electronic differences between 36-bit and 24-bit scanners. The digital analog converter (DAC) chips convert light into numbers that the computer can process. DACs are very complicated chips. They're difficult to manufacture. Most DACs are inaccurate at their least significant bit.
The least significant bit is the lowest value a binary number can have above zero. To prevent the least significant bit from appearing as random distortion, noise is added. This is called dither. It insures that the least significant bit is always set.
In a 24-bit scanner the DAC is only 8 bits. If dither is added to the image then the real color resolution is only 7 bits. That's 128 levels of intensity for each primary color. If there is no dither, the image will probably have distortion. Distortion can be seen as color unevenness or as an overall "warmness" or "coolness" of an image.
36-bit scanners also have distortion in their least significant bit. But since the DAC in a 36-bit scanner is 12 bits instead of eight, the distortion is much less pronounced. It is also easier to add dither without losing effective color resolution.
The result isn't more colors. You're reducing the color resolution down to 24-bits in your image editing software. But your scanned colors will be truer and require less correction before printing.
When shopping for a 36-bit scanner, make sure the digital analog converter chip is a full 12 bits and that the extra color resolution isn't interpolated. Interpolated color is no better than interpolated resolution. U
