In a recent November newsletter, Lasersoft Image, developers of SilverFast, announced a dramatic boost in the quality of scans with their patent pending Multi-Sampling with Auto-Alignment. With Multi-Sampling low-end scanner can behave as if you had purchased a high-end scanner. What differentiates high-end from the low-end scanner is the low noise of these scanners, due to the cooling of the CCD and other constructive methods. This cooling eliminates image noise and less image modification needs to be done to acheive high quality images.  

What is the Dynamic Range Increase?

SilverFast measured the Dynamic Range increase according to the new upcoming ISO standard ISO 21550 and SilverFast’s new Multi-Sampling has a higher improvement level for the scanner Dynamic Range. It is interesting to see that even for scanners that already have Multi-Sampling built into their hardware such as the Nikon LS5000, there is a significant increase in Dynamic Range from 2.9 to 3.4. 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 densiometers, 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 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.

How does Multi-Sampling work?

With multiple sampling turned on, SilverFast will perform either 4, 8, or even 16 scans during scan time. You can specify the count, usually the more the better. After performing the scans, the single images are averaged together into one image. Since noise is random, a special averaging procedure will cancel only the noise but leave the image details untouched. There is a problem associated with this process: Every scan might not exactly be in the same position with reference to each other, so normal averaging would blur the resultant Multisampling scan. That is why LaserSoft Imaging had to develop an intelligent auto-alignment, so no blurring effect can occur.