It was predicted in the early 1990ís that by 1995 drum scanning would be obsolete. Part of this prediction was based on the explosion of well-engineered, low-cost flatbed desktop scanners.
Some of the predictions were true. Drum scanning did decline and CCD-based sensors are the most popular image capture technology used. However, drums scanners did not die. What happened was a new crop of desktop baby drum scanners emerged.
As scanning technology evolved, CCD-based scanner vendors and end-users were claiming that CCD scanners were just as good for creating scans with good shadow details as drum scanners. In some cases, CCD-based scanners are as capable as PMT scanners. However, by examining scanned results and listening to a number of end-users and vendors, there is still a line (however fine at times) between high-quality drum scans and high-quality flatbed scanners.
Talking the Talk
Here is a brief scanning terminology lesson: in any type of scanning solution, there are eight important attributes: the scannerís media type; its light sources and filters; sensors and related systems; the scannerís mechanics (drum or flatbed); how well it performs (speed); image processing features; connectivity; and cost. Of those eight attributes it is the scannerís sensor system that is the most critical to attain the best quality.
The purpose of a scannerís sensor system is to convert light from the original image into electronic data Ė the original gets digitized into pixels. There are basically two types of sensor-based systems: Photo Multiplier Tubes (PMTs) used in drum scanners; and Charged Coupled Devices (CCDs) used in flatbed scanners.
Resolution and dynamic range are also important. Resolution is the number of pixels a scanner can acquire, while dynamic range describes the sensorís ability to measure the number of shades or tones from white to pure hue, or black.
The heart of the PMT verses CCD debate is based on how shadow details are captured by scanners. Drum scanners using PMTs are known to have better shadow details due to less electronic noise. This enables the scannerís sensors to distinguish more clearly between density areas in originals. The result is more shadow details and less grain. Some CCD-based scanners struggle with detecting shadow details. The resulting scan can lack shadow details and become grainy.
More Specialized Apps
The predominant businesses that use drum-scanned images these days are art galleries, photography-based operations and businesses with large image collections. One thing you'll notice from the various businesses we spoke to for this piece is that they are all doing very specialized work with very specific clients.
Clay Burneston of the National Geographic Society (NGS) is involved with producing the color scans for the National Geographic Magazine. NGS is still using drum scanners (Heidel-berg PrimeScans) for scanning positive film (like 35mm transparencies) and is in the process of purchasing a new drum scanner for a big image archiving project.
Joe Lapino of PixelNation, a small Pennsylvania-based company, provides lower cost, high-quality images from color negatives for photographers using an Aztek drum scanner. Lapino says "PixelNation focuses only on a discriminating clientele of photographers and is committed to working closely with customers to give them the best quality images possible."
Bob Grove, director of Digital Imaging Services at the National Gallery of Art in Washington, D.C, uses a Howtek D4000 to scan positives (such as 35mm, 4x5 and 8x10 transparencies). In relation to drum scanning, Grove says the issues are relatively simple about why he likes a drum scanner. "Drum scanners offer the best shadow details and create high resolution images. I canít imagine not having one."
NancyScans serves 8,200 commercial photographers providing them with custom scans of their specialized work using the Heidelberg Tango drum scanner. Company president John Olson told us they scan a range of originals from black-and-white and color transparencies to color negatives and reflective originals. He also told us his business is "based on getting the best scan possible using a drum scanner."
In 1995 there were a number of mainstream companies that manufactured drum scanners, including Danagraph (Scanview), Dupont/Fuji, Howtek, Isomet, Linotype-Hell (Heidelberg), Itek Colour Graphics (ICG), Optronics and Screen.
Today in 2003, drum scanning is alive in a niche market where new and used models are still being sold. However, there are only a handful of companies that sell them, such as Aztek, ICG, Heidelberg and Screen.
The price of drum scanning has dropped significantly since the first drum scanners were marketed in the 1970s and 1980s. There was a time when the cost of a fully outfitted drum scanner was upward to $500,000. Today, the cost of a refurbished drum scanner can start around $5,000 and increase to over $45,000 for a brand new, top-of-the-line unit.
The Bottom Line The short answer to the question of whether CCD scanners create good results is yes, they do. And there are good products to choose from Ė as youíll find in the Flatbed Scanner Round-up on page 35. In some businesses, there is no need for a drum scanner. CCD-based scanners can produce good, if not very good color, depending on your business requirements. However, it is clear that when you need to create the highest quality scanned image from film originals, a drum scanner is still one the best tools to use. The frequency of the applications where this process is necessary will obviously drive your decision on whether a drum scanner Ė new or old Ė should be part of your product mix.