Conventional software-based dust and scratch removal tools
Slides and negatives always have small dust particles and tiny scratches on them, even when handled very carefully. There are several software-based techniques to remove these defects during the scan process by considering the surrounding image information. However, it is hardly possible for these tools to differentiate between actual scratches and image details to be preserved. Thus, often not all defects will get removed, many details will get lost or a very time-consuming manual retouch is necessary. LaserSoft Imaging has developed a solution for this problem:

SilverFast's hardware-based dust and scratch removal tool with infrared technology (iSRD®)
Contrary to coventional techniques the SilverFast dust and scratch removal functionality iSRD® is based on the hardware. It is using the scanner's infrared channel for defect detection. Infrared light has a very wide wave-length, which allows it to pass through film emulsion of negatives and slides without resistance, as opposed to scratches and dust particles that reflect it. iSRD® utilizes this behavior as follows. The image is getting scanned two times - the first is the regular RGB scan and the second is the additional infrared scan that captures defects like dust and scratches only. Then the calculative dust and scratch removal takes effect, where the infrared channel has detected any defects. This way no important details get lost.


Example images: Before and after iSRD® dust and scratch removal.
(Click the images to enlarge them)

Further advantages of SilverFast iSRD® over other systems
Some manufacturers have developed their own systems to remove dust and scratches such as FARE or Digital ICE. SilverFast iSRD® differs in many ways with more sophisticated functions and additional features:

• iSRD® supports up-to-date multi-core processors.
  Thus, iSRD® is running especially fast on systems using the technique of multi-threading.

• Automatic Mode: iSRD® is working on its own, without requiring the user to make any adjustements. The removal is affecting the complete active scanning frame.
• Manual Mode:For challenging corrections and optimum results the user is able to optionally configure iSRD® himself. In detail:
• Any corrections and adjustements are shown in a preview window.
• The sensitivity of defect detection is controllable.
• The area around defects getting used for corrections is adjustable.
• Layers and masks can be used to apply varying corrections to different parts of the image.
• iSRD® and SRD® are usable in tandem for optimal defect removal.
• Through utilization of iSRD® & SRD® and several layers & masks it is even possible to remove dust and scratches from very challenging film material like Kodachrome or B/W-film reliably. This is not achievable with similar systems from other manufacturers.*

The following movie shows how quickly and easily you can achieve great results using SRD® & iSRD®:



Example image: Before and after applying the SilverFast Kodachrome workflow including iSRD® dust and scratch removal. (Click the image to enlarge)

See how effectively SilverFast iSRD® and HDRi work:

Source	Infrared	Marker	Result
Source	Infrared	Marker	Result

*Scanning silver halide black and white films with iSRD® can produce artifacts in your pictures. In such cases it is recommended to use the software-based SRD® technology. Black and white chromogenic films developed with C-41 should not present any issues with iSRD®.

Note: SilverFast iSRD® cannot support any scanner that is not equipped with infrared technology.
Please verify that your scanner supports iSRD before buying.
The SilverFast SE versions only contain the automatic mode.