Magazine article Computers in Libraries

Scanning for Digitization Projects: Making Good Scans Means Doing More Than Just Pressing Buttons. If You Understand What Software to Choose, Which File Formats to Use, and What the Specifications Really Mean, You Can Create Digital Images with Optimal Quality

Magazine article Computers in Libraries

Scanning for Digitization Projects: Making Good Scans Means Doing More Than Just Pressing Buttons. If You Understand What Software to Choose, Which File Formats to Use, and What the Specifications Really Mean, You Can Create Digital Images with Optimal Quality

Article excerpt

Librarians and archivists find themselves facing the prospect of digitization. Everyone is doing it, everyone needs it. Discussions rage nationally and internationally concerning what to digitize and the best means to present and retain digital objects. Yet newcomers may seek answers to simpler questions. What is digitization? What does digitization equipment do? What do digitization standards mean?

Digitization is the act of making something digital, expressing a physical object "in numerical form, especially for use by a computer" (The American Heritage, 2000). In the similar manner that paintings express landscapes and faces through colored pigments, digital files represent objects as numbers. It is, to misuse a phrase, painting by numbers.

Why should an object be represented by numbers? What is gained by doing so? The aim of expressing an object in numbers is that it can be stored and manipulated by computers. Computers are number crunchers, performing millions of calculations per second. By digitizing an original and placing a digital copy of it on a computer, the file can be manipulated, transferred, and stored with ease. Storage and distribution are the primary factors behind the national push for digitization. Storing a numeric or digital representation of photographs on a CD takes up far less physical space than the boxes and photo albums stored on shelves. Being able to access digital copies of material across the Web allows patrons greater access to the content without increased wear and tear on the original.

Understanding the Digitization Equipment

Digitization equipment--such as flatbed scanners, digital cameras, and digital audio/video recorders--generates digital copies of physical objects. Flatbed scanners are, in short, desktop photocopiers and they are mostly mechanical devices. (1,2) A lamp moves slowly across the face of the original. The lamp shines light onto the original, and the reflected light is focused through a series of mirrors and lens onto the recording medium. In flatbed scanners, the medium is a compact light sensor, either a CCD (charged coupling device) or CIS (contact image sensor), each of which is composed of hundreds or thousands of elements. When light strikes each element, the intensity of the light is assigned a number. The numeric reading of light intensity and element position are recorded in sequence into a file, which forms the digital version of the original.

Additional hardware can enhance the scanning process, but does not affect the basic function. Transparency adapters make it possible to digitize slides, negatives, and transparencies. Rather than reflecting light off the surface of a transparent original, a transparency adapter shines light through the original and onto the CCD/CIS. Automatic document feeders increase the speed of the scanning process by handling the placement and removal of paper originals from the glass plate, reducing the delay between scans. The downside to automatic document feeders is that the originals must be loose (in the case of books, pages must be disbound) and able to withstand the physical stress of being run through the feeder.

Regrettably, manufacturers of consumer-grade scanners also adorn them with buttons displaying icons for email, photos, text, and the printer. Pressing each button activates a preset scanner setting, causing the scanner to scan an original and format it for email, pictures, text documents, or the printer. These buttons make the process of digitization easy; they remove any need for the scanning technician to understand the process. Push the button, it's made to order. Unfortunately, none of the buttons installed on flatbed scanners are preset for "digital archive" quality. In order to get the quality recommended by the Digital Library Federation (www.diglib.org), scanning operators need to understand what the buttons do and how they can do it better.

The Scanning Process

While the flatbed scanner does the actual digitization, the device has no understanding of what operators want for output nor does it store the files or perform alterations. …

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