Weblog von Rasch-Diascan
(Hier geht’s zur deutschen Version.)
The infrared files provided by the scanner also serve as a basis for manual photo processing to distinguish between image details and dust, scratches or mold stains. The image is a good example of the first mold stains spreading inward from the right edge of the image on the slide from the 1990s. As long as no threads of mold are growing in the color emulsion, good results can be achieved with IR-Clean. For all collections with unknown slide film types, the infrared file helps to identify Kodachrome slides or other infrared-blocking slide films.
The quality of the digital restoration can be checked by using the additionally provided JPEG files without IR-Clean. By quickly switching between two images with and without IR-Clean image defects such as dust, scratches or mold become visible – the video explains the basic technique. This allows customers to carry out individually optimized post-processing themselves using standard image processing programs. At the same time, the results can be checked for any artefacts, even if the risk with IR-Clean is very low.
The IR-Clean technology was designed for film scanners with an area camera and was developed in 2018 as part of a funded project by the Engineering Office Helmut Rasch. Comparable alternatives such as Digital ICE (Kodak), iSRD (Lasersoft Imaging AG) or Infrared Clean (Hamrick Software) typically only support line scanners, which have a low speed due to their design.