Drum Scanning

Scanning
Using the legendary Crosfield Magnascan we supply scans of the highest quality, capturing a wider density range than any flatbed scanner, the highest resolution, and with on board colour management and sharpening (USM) - no other scanner produces better quality from reflection or transparency copy.
Combined with the Celcis link to our Macintosh workstations we can softproof and analyse scans on our calibrated monitors before and after scanning using a 'prescan' workflow.
With the Crosfield Celcis link, high volume scanning can be undertaken allowing us to batch scan, with up to 100 transparencies mounted to one drum, simultaneous correcting and scanning can be achieved.

Mounting
With a huge analyse drum size of 510x635mm very large originals can be scanned, both reflection (photographs, paintings, artworks) and transparency copy originals. A special mounting cradle is used to ensure originals 'wrap' to the drum for tightness. Special overlay foils maybe used for some reflection copy originals.
For the highest quality scan a transparency original is recommended to be supplied, transparencies are carefully mounted in oil (wet mounting) to avoid newton rings and reduce the effect of any scratches or marks.
After scanning the drum is placed adjacent to the Macintosh monitor, in front of a corrected light source for colour correction.
Scans are then further cleaned (cloning) on the workstation, removing dust or scratch marks.
Transparencies are then supplied back dry and clean of any oil.

Technical
Many new clients come recommended, being instructed by the design agency to supply 'drum scans' - but some ask - why drum ? A drum scanner uses a totally different technology to flat beds for capturing image data from reflective or transmissive copy, for professional high quality purposes a flatbed cannot produce a good enough scan.
A flatbed scanner cannot scan at the required resolution, the image is not sharp and will lack detail in the highlight and shadow areas.
A drum scanner is a huge piece of scientific equipment costing many 10's of thousands of pounds, weighing up to half a tonne, in essence you get what you pay for.

For a quick technical explanation, drum scanners use Photo multiplier tubes (PMT) as opposed to Charged Coupled Devices (CCDs) in flatbeds.
Three PMT's are used to capture the R (red) G (green) B (blue) pixels as the drum spins at high speed - driven by a powerful xenon light source - seeing into dark areas (shadows) and capturing the very light areas (highlights), this wider density range (Dmin and Dmax, 0-4D+) is not possible with flat bed scanners.
This light is then decoded into pixels of varying value at 16 bit depth.

Additional focus and aperture size adjustments (both at the head and at the light source) make for very sharp and colour accurate scans. Control of the light out, and in, allow for ultimate control in the scanning process. These controls are not present on flatbed scanners.

A true higher resolution (no interpolation) up to 8000dpi is available, scans up to 1 gigabyte are necessary for very high quality litho work, large format printing or long term storage and archival purposes. A flatbed CCD sensor has limited resolution capabilities - it needs to interpolate the data to give a high resolution scan, this process introduces aberrations to the final scan, and accentuating grain.