PhotoshopNews.com
Nov 8, 2005

Dynamic Range of all scanners significantly enhanced!

SilverFast’s Multi-Sampling brings Scanners to a new Level of Quality

Press Release: Kiel, Germany, Nov. 8th, 2005, from LaserSoft Imaging, Inc. SilverFast Ai STUDIO and SilverFast SE Plus supply the most dramatic boost in quality to scanners with SilverFast’s patent pending Multi-Sampling with Auto-Alignment.

What differentiates a very expensive high-end scanner, such as drum- or Linotype-Hell or Scitex Flatbed scanner, is the low noise of these scanners due to cooling of CCD and other constructive methods. When a scanner has very low CCD-noise so much more Unsharp Masking can be applied. That is the main reason that high-end scanners deliver very sharp and brilliant scans.

Dynamic Range Increase with SilverFast Multi-Sampling
We have measured the Dynamic Range increase according to the ISO standard ISO 21550:2004 and we have found that SilverFast’s Multi-Sampling yields dramatic improvement for scanner Dynamic Range. It is interesting to see that even for scanners that already have Multi-Sampling built into their hardware, there is a significant increase in Dynamic Range. That exemplifies the unique quality of SilverFast’s Multi-Sampling process.


What is DMAX, Dynamic Range and Density?
Image density is measured from image brightness with optical densitometers, and ranges from 0 to 4, where 0 is pure white and 4 is very black. More density is less brightness. Density is measured on a logarithmic scale. Density of 3.0 is 10 times greater intensity than a density of 2.0. An intensity range of 100:1 is a density of 2.0, and 1000:1 is a density of 3.0. Density 4.0 (which is 10.000:1) is not a theoretical maximum, the math is not limited, but it is a practical maximum of density, because almost nothing you can scan will reach 4.0.

The minimum and maximum values of density capable of being captured by a specific scanner are called DMin and DMax . If the scanner’s DMin were 0.2 and DMax were 3.1, its Dynamic Range would be 2.9. DMax implies that unique image tone values are distinguishable, and not hidden by electronic noise. Greater dynamic range can detect greater image detail in dark shadow areas of the photographic image, because the range is extended at the black end.

DMAX is a value describing how much light variations an input device can differentiate. In general manufacturers publish a value that does not relate to the true usable maximum dynamic range, instead it is a theoretical value. When a scanner can still see light variations such as in the shadows of a scan but the CCD already produces visible noise rendering the scan unusable. So briefly speaking DMAX is the maximum density a scanner can detect, while Dynamic Range is the usable range of shades a scanner can differentiate.

For more information, see the SilverFast web site.

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