What can software do to improve a scan?

I imagine publishing houses, museums and end-users must still have shoe boxes full of film and slides with anything on them from holiday shots to historical scenes. Digitizing the analogue images is easy enough these days: you buy a good scanner and start scanning that film. The challenge is to get scans that can compete with digital photographs. That's where the scanning software comes in.

These days, if you own a Snow Leopard machine, you can just hook up your scanner to the Mac and Image Capture will recognize it (if it's a bit recent and mainstream). You will even get the opportunity to fine-tune your scans in the area of colour and sharpness. The results will be mediocre unless your slides and film are in perfect condition, without any dust or scratches and shot with perfect material and under perfect conditions.

If that was not the case—and the laws of physics dictate it won’t be—your images will need a lot more than some basic corrections. Even if you own the most expensive scanner available—let’s say a Hasselblad Flextight scanner—the results you’ll get will heavily depend on the software used. The reasons are well known: even museums can’t archive slides and film in perfect conditions and guarantee there won’t be a scratch visible or some colour shift happening.

Some software can get very near to perfect results, though. By exploiting modern scanners’ technical and optical capabilities to the fullest, the scanner software can do more than just turn on the lamp and move the scanning element. It can detect and remove dust speckles and scratches, it can sharpen the image, colour correct the image. It can even correct photographs that due to old age display colour shifts you normally can’t correct in one Photoshop session.

Until recently, most of the high-end capabilities of scanner software were confined to the scanning operation itself. You couldn’t carry all the information an Epson V700 Photo scanner is capable of picking up to any other application, for example. Instead, you had to carry out all corrections in the scanner software itself. With an application like SilverFast Ai that wasn’t too bad because of the feature-completeness of this software, but if you needed to scan hundreds of images, it became inefficient.
The SilverFast Archive Suite edition changes all that and moves the editing task to a dedicated application in the workflow, away from the scanner software.

In SilverFast Archive Suite version 6.6.1 the 64-bit HDRi color files and 32-bit grayscale files contain all readable image information including the information of modern scanners’ infrared channel, using this data for image optimization, e.g. dust and scratch removal. As we already wrote in our previous coverage of SilverFast Archive Suite, HDRi RAW data is perfect source material for later post processing.

But scanner software can do even more than capture all available information. If the software not only saves image data but data from the scanner engine itself as well, you can use this data to further enhance the image. The scanner data can allow for advanced automatic Unsharp Masking, for example. The software takes the specific scanner details into account and is therefore able to produce more brilliant, sharper images.

Take a look at these photos: St. Paul’s with Auto Sharpen and infrared based dust and scratch removal—

A fragment without infrared dust and scratch removal—

The same fragment with infrared dust and scratch removal. Note the disappearance of two black spots in the wall area.

Kodachrome scanning: not necessarily a nightmare

In analogue processing environments, it’s the film lab that guarantees the colour accuracy. In digital workflow, it’s you who needs to take care of colour through a colour management engine. Except for professional scanner operators, printers, and colour management experts, few people really understand how colour management works. Scanner software can take away that pain by automating the calibration process.

To improve the workflow in publishing production environments, automatic colour calibration can help speed up the scanning process by ensuring colour accuracy. In the last versions of SilverFast, a combination of automatic frame detection and barcode technology integrated with LaserSoft Imaging’s IT8 targets, makes the calibration process completely automatic—even the downloading of reference files is done automatically.

Colour management being a really crucial part of any scanning process, LaserSoft Imaging manufactures high-quality IT8 targets themselves, in small batches so that accuracy is guaranteed.

For Kodachrome workflows, the software must help to get rid of the innate blue colour cast. To really work, a device specific calibration with a Kodachrome target is needed. Generic Kodachrome ICC profiles are one possibility. However, for really accurate results you will still need a scanner calibration. This is the only right way to approach Kodachrome scanning—and you don’t need to take our word for it.

Another way software can help produce the best scan possible is by maximizing the scanner’s dynamic range. To stay with Kodachromes: their dynamic range reaches up to 3.8D - which is a grayscale range of 6300 shades and equals a contrast range of 1:6300.

The dynamic range of a scanner is a measurement for a scanner’s capability of recognizing contrast levels. Contrary to reflective originals, transparent originals like monochrome film, colour negatives or slides consist of multiple film layers, which respond to light differently.

That is why transparent originals achieve a high dynamic range which usually exceeds a scanner’s possibilities. Especially in the very light and shadow image areas, image details will get lost when scanning. The dynamic range of each stage (capture, scanning, editing and storage) plays a crucial role in the quality of the final output.

Doing two separate scans with a second one using an increased exposure time may capture the light image area’s details in the first pass and the the shadow details in the second. Afterwards an algorithm calculates the final scan, which contains more detail, combining the two single scans.