However, a lot of restoration can be performed during the scanning stage, with a lot more success than later Digital Restoration, if the technology used is applied correctly, and if it is truly using as much of the 'lost' information as is possible.

The term 'using as much of the lost information as possible' may appear a strange one at first sight, but there is a reality behind it most people fail to understand.

Many scanning based restoration systems simply 'map' the problem areas, as with infrared based error mapping, available on some film scanners.

Here the problem area is simply flagged for later digital restoration, with no attempt to relocate the missing image data.

Relocate the missing image data???
As crazy as that sounds, with a lot of optical film damage it is actually possible to do exactly that!

When the damage is a surface scratch or dust particle the image data is actually still there in the film frame, but the light passing through the film frame gets scattered, preventing the imaging sensor from seeing the image detail, resulting in the scratch and dust being visible in the scanned digital image.

With better optical sensing systems it is possible to actually capture this scattered image information and restore it back into the scanned image...

With Cintel's diTTo with D/SCO option this exactly what happens, and is a truly amazing optical scanning restoration system.

D/SCO (Dust/Scratch Concealment Option :o) user control allows for a controllable amount of ‘optical’ correction at the scanner itself, and works with all film emulsions including Black and White stock as it's not reliant on the more common Infrared approach, and allows the visibility of dust, scratches and film grain to be optimised directly from the diTTo scanner, not by substituting the defective pixel, but by capturing the missing image detail and restoring it to the image. Very cool!

The above images show a raw diTTo scan without D/SCO, and then again with D/SCO implemented. The difference is obvious, even in these small images.

Additionally, the D/SCO option can output an error map as an associated alpha channel to enable later additional digital restoration to be performed on areas where the original image data could not be restored via D/SCO.

From this error map non-linear DI systems, such as Quantel's iQ, can use digital processing techniques to improve on the real-time restoration performed during scanning using specific plugins or user based restoration techniques, such as hand painting, within the DI session.

Image Stability
Another area that gets a lot of coverage when scanning film is image steadiness.

Often, pin registration is seen as the way forward, as is performed on most film scanners, as this locks the frame during scanning using pins inserted into the film frame's perfs.

However, with telecine based scanning as with Cintel's dataMill, or when pin registration is not possible for other reasons, an alternative approach has to be used.

One recent development is to use electronic real-time image registration, as with Cintel's STEADY system, which can be simply added into the image scanning path to provide real-time image steadiness.

With the ability to re-position an image +/- 5 to 6 lines/pixels, to an accuracy of 1/8th of a pixel, with no resultant artefacts, electronic image stabilization is becoming a real alternative to pin registration, and without the potential for film damage on older film stocks due to shrinkage or warping resulting in the registration pins not aligning with the film perfs correctly...

For more information on diTTo, D/SCO and STEADY see the Cintel website.