London-based color management specialist Light Illusion has developed a new application for its MatchLight IMS (Image Matching System) to guarantee the long-term viability of film-based archives for digitally acquired images.
With the explosion in digital acquisition, and the difficulty in providing long-term archiving of the images, Light Illusion was asked by a number of clients to look at possible long-term archive systems based on the use of standard film stocks.
The problem with the use of film has been guaranteeing the accuracy of the recovered digital image due to the variable nature of the recorded film image and settings within the film transfer scanner or telecine. Light Illusion’s system overcomes these problems.
The requirement was to develop a process for film-based archiving using standard film recording systems that automatically retains the digital image in as near perfect state as the original when the image is scanned from the archive film.
Light Illusion had the core component for this process already in the Light Illusion tool-box – MatchLight IMS (Image Matching System) – widely used for matching on-set and dailies workflows, as well as ACES workflows for VFX operations.
MatchLight IMS is a system that auto-generates a LUT from two versions of the same image (or string of images) – basically a before/after comparison, with the difference between the two being converted into a LUT for use within any color system, or via Vulcan, Light Illusion’s command line application for large volume batch image processing.
By applying a short string of ‘technical images’ before each and every archive it is possible to guarantee the recovered image integrity after re-scanning, with the original technical images and the re-scanned versions of the same images being used within MatchLight IMS to auto generate the required calibration LUT to return the scanned images to their original color, dynamic range and contrast, generating a near perfect clone of the original images.
The results using Kodak Intermediate stock have proven to be very accurate – to the point where visually the match is perfect, with just small variations at a pixel level.