Articles: Other

Bookmark and Share

Pages: [ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 ]

Digitizing Quality

Now that we’ve gone through the “academic” part of our tests we can try the scanner with different typical originals. The first scan I’m going to show you is an X-ray image. This type of the original is the most difficult for a non-specialized scanner (in other words, for all SOHO class scanners). If you’re not in the know, the scanner must have a very high dynamic range or density range parameter to scan such an original successfully since X-ray images have the highest density (i.e. they are the darkest of all). Let’s see what we have here:

X-ray image scan

An ordinary scanner could hardly have passed this test because most SOHO devices typically have an optical of density of 2.4Dmax. The EPSON Perfection 4990, as you remember, boasts a density of 4.0Dmax. The processing of such difficult originals is made possible by the further optimization of the spectral characteristics of the scanner’s lamp. Why “further”? Because EPSON had made a jump from 3.4 to 3.0Dmax back in the last year with their Perfection 4870. The manufacturer had had to perfect the Dynamic Range Control system especially for that model and this had led not only to a wider density range, but also to smaller scan times with transparent originals! As you can see now, the EPSON engineering people didn’t stop, but spent the last year implementing further improvements.

The following is a medium-format transparent original scanned at the maximum optical resolution:

Medium format KODAK Ektachrome E100S film scan

Scan fragment of actual size

As another example I want to show you a scan of volumetric objects. These are a handful of markers scattered on the scanner’s bed. This image helps to evaluate the sharpness depth of the scanner visually.

Volumetric objects scan

Pages: [ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 ]


Comments currently: 3
Discussion started: 12/21/05 11:49:02 AM
Latest comment: 02/04/07 01:34:37 AM

View comments

Add your Comment