Film scanner

Film scanner
Nikon Coolscan V ED 35mm film scanner (right)
CanoScan9950F, a flatbed scanner that can also scan film

A film scanner is a device made for scanning photographic film directly into a computer without the use of any intermediate printmaking. It provides several benefits over using a flatbed scanner to scan in a print of any size: the photographer has direct control over cropping and aspect ratio from the original, unmolested image on film; and many film scanners have special software or hardware that removes scratches and film grain and improves color reproduction from film.

Film scanners can accept either strips of 35 mm or 120 film, or individual slides. Low-end scanners typically only take 35mm film strips, while medium- and high-end film scanners often have interchangeable film loaders. This allows the one scanning platform to be used for different sizes and packaging. For example, some allow microscope slides to be loaded for scanning, while mechanised slide loaders allow many individual slides to be batch scanned unattended.

Contents

Dust and scratches

Dust and scratches on the film can be a big problem for scanning. Because of their reduced size (compared to prints) the scanners are capable of resolutions much higher than a regular flatbed scanner; typically at least 2000 samples per inch (spi), up to 4000 spi or more. At these resolutions dust and scratches take on gigantic proportions. Even small specks of dust, invisible to the naked eye, can obscure a cluster of several pixels. For this reason, techniques have been developed to remove their appearance from a scan, see film restoration.

The simplest is the median filter, often called despeckle in many graphic manipulation programs, e.g. in Adobe Photoshop and the GIMP. It works by examining a pixel in relation to the pixels surrounding it; if it is too different from the surrounding pixels then it is replaced with one set to their median value. This and other methods can be quite effective, but have the disadvantage that the filter cannot know what actually is dust or noise. It will also obliterate fine detail in the scan.

Infrared cleaning

Infrared cleaning works by collecting an infrared channel from the scan at the same time as the visible colour channels (red, green, and blue). This is done by using a light source that also produces infrared radiation, and having a fourth row of sensors on the linear CCD sensor. Photographic film is mostly transparent to infrared radiation (no matter what the visible image contains) but dust and scratches aren't, so they show up in the IR channel. This information can then be used to automatically remove the appearance of dust and scratches in the visible channels and replace them with something similar to their surroundings. A major limitation of this technique is that it can only be used on dye-based (color and chromogenic black-and-white) films; the image-forming silver particles in most black-and-white film stocks are opaque to infrared radiation.

Scanner manufacturers usually have their own name attached to this technique. Kodak developed Digital ICE at their Austin development centre, and is licensed by Epson, Nikon, Microtek and some others. Canon developed its own FARE (Film Automatic Retouching and Enhancement) system. LaserSoft Imaging is developing the iSRD Dust and Scratch Removal, on which among others Plustek is relying.

See also

External links


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Film Scanner — HD Usually refers to a high resolution Film to Data device that does not operate at “real time” (ie at least 24 frames per second). Also see Telecine …   Audio and video glossary

  • Motion picture film scanner — A motion picture film scanner is a device used in digital filmmaking to scan original film for storage as high resolution digital intermediate files. A film scanner scans original film stock: negative or positive print or reversal/IP. Units may… …   Wikipedia

  • Film-out — is the process in the computer graphics, video and filmmaking disciplines of transferring images or animation from videotape or digital files to a traditional celluloid film print. Film out is a broad term that encompasses the conversion of frame …   Wikipedia

  • Film speed — is the measure of a photographic film s sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to measure the sensitivity of digital… …   Wikipedia

  • Film holder — A film holder is a device which holds one or more pieces of photographic film, for insertion into a camera or optical scanning device such as a dedicated film scanner or a flatbed scanner with film scanning capabilities. The widest usage of the… …   Wikipedia

  • Film stock — This focuses on motion picture film. For still photography film, see photographic film. A film strip Film stock is photographic film on which filmmaking of motion pictures are shot and reproduced. The equivalent in television production is video… …   Wikipedia

  • Film preservation — Stacked containers filled with reels of film stock. The film preservation, or film restoration, movement is an ongoing project among film historians, archivists, museums, cinematheques, and non profit organizations to rescue decaying film stock… …   Wikipedia

  • Scanner (Datenerfassung) — Zwei Flachbettscanner Modernes Spiral CT Gerät Ein Scanne …   Deutsch Wikipedia

  • Scanner Cop — Infobox Film | name = Scanner Cop director = Pierre David producer = Pierre David writer = Pierre David starring = Daniel Quinn Darlanne Fluegel Richard Grove Mark Rolston music = Louis Febre cinematography = Jacques Haitkin editing = Julian… …   Wikipedia

  • Scanner — Scan|ner 〈[ skæ̣nə(r)] m. 3〉 Gerät, das ein Objekt (z. B. ein Foto) mit einem Elektronen od. Lichtstrahl punkt od. zeilenweise abtastet u. die dabei anfallenden Messwerte zur weiteren Verarbeitung in meist digitale Signale umsetzt [engl.; zu scan …   Universal-Lexikon

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”