For film and fiche scanning, what is your REAL speed to scan, process, QA and then output – not just how fast a scanner can theoretically capture a roll of film? Strip scanning software (vs. Ribbon Scanning software) can only Scan or Output, but not both at the same time. This dramatically affects your system throughput. Scanning and processing cannot be done at full rated speed without the addition of a high performance storage system. Will your scanner vendor provide this? Remember that a key component to accurately secure that a conversion project is completed within time and under budget – that is to maximize your productivity and ROI – is the Production Throughput and NOT the theoretical scanning speed stated in manufacturer data sheets. The strip scanners have their production bottleneck in the image processing step and not in the image scanning. Image processing can take up to two times as long as the image scanning; therefore, strip scanners theoretical scanning speeds do not really measure the true speed of a scanner. You want to verify what is the speed to complete the 4 basic steps in your process? a) Image Scanning, b) Detecting images and generating meta-data, c) Audit/QC, d) Output. Furthermore, you not only want to verify that you have the best Production Throughput in the market but also the best Image Quality produced with RAW, uncompressed data captured with true optical resolution (without interpolation / scaling or “douple speed” i.e. half resolution).
The most important metric for a scanner is the total throughput for fully processed rolls into satisfactory images per the user’s specification and how much operator time this requires. This information cannot be easily found from the manufacturers specifications as every application is different, and at times the information available can be misleading. Furthermore, when all stated vendor specifications are reviewed, are you really comparing apples to apples?
Beware speeds quoted on a manufacturer product datasheet. Many times, these are quotes based on very best case scenarios (the perfect film with simplest scanning parameters), or these quotes can be numbers that are not realistic for any scenario. For example, a scanner rated at 325-350 pages/minute might actually only produce about 250 pages/minute using standard film (16mm, 200 dpi, 24x reduction ratio, 8.5” wide image with a 2.5” gap between frames). The speed quoted on the product specifications may have been declared using a 0 gap between frames, a different reduction ratio or low resolution – all of which may not be realistic for film scanning in a real world scenario. There are some vendors who think when you specify a 200 dpi image, that they can supply an image scanned at 100 dpi, by 300 dpi and then scale the image to 200 by 200 dpi. The image quality is abominable, but since they get to scan at 100 dpi in the scanning direction, they get twice the speed and you get half the image quality. Some vendors call this “double speed”, when they really mean ½ image quality.
Additionally, when quoting speeds for processing entire rolls of film, many times it is not specified for the reader the length of the roll and the type of resolution being employed to arrive at those numbers.
The actual speed of any film scanner is going to always depend on the type of film being scanned and the user’s image requirements. More importantly, speed should really be measured in terms of the overall scan process, not just how fast the scanner can capture a roll of film. Scan time, detection editing, image conversion and QC are all relevant factors.
Once the film has been scanned, the majority of the processing is still left to be done. This is where the differences in productivity can show up between technology providers, and the differences can be huge.
Stand alone scanners where the same computer that is performing the scanning is also doing the processing of the images will typically have about ½ the throughput of the scanner’s “rated” speed. Scheduling the processing to run overnight can help bring the scanner back to its rated speed, but many problems show up overnight that often stop the processing or render the results useless.
The limiting factors here are the hard disk speed, memory, and processing power. For evaluation, doing a system design of the workflow and then running an entire shift on the scanner is prudent, so that bottlenecks in processing or moving the image data can be determined. Slowdowns may not occur until the hard drive gets fairly full. Data from a hard drive cannot be moved while the scanner is scanning. Scanning and processing cannot be done on the same machine simultaneously at full rated speed without the addition of a high performance storage system. With the addition of a high performance storage system, processing time can be cut in half in most situations.
With a standalone scanner (no high performance storage system), non-productive operator time waiting for the scanner is approximately 50% – and this is if no rescans need to be performed. With a networked scanner, combined with true Ribbon Scanning, high performance storage and a second workstation, the software and operator are able to perform detection, processing and QC on a second workstation while the scanner is operating, maximizing operator productivity and scanner throughput.
