Telecine is Dead!
Moore’s law in computing performance and storage capacity has made the traditional telecine film transfer model obsolete.
In recent years, the film transfer process has transitioned from the use of traditional telecine equipment (e.g. Spirit, Cintel) that outputs only video, to modern film scanners (e.g. ScanStation, Director, ARRISCAN, etc.) that output digital files in a variety of formats. This evolution has been driven by dramatically improved performance and quality of image scanning technology coupled with explosive growth in computing power and storage capacity.
Telecine Image Quality is Inferior to Scanners
Real-time scanning was required in the old days when the only viable image “pipe” was a real-time video channel. In those days, everything had to be sacrificed for speed. As a result, telecines generated real-time video at the expense of noisy and highly unstable images (all telecines are edge-guided which causes extensive weaving).
With the advent of the Digital Intermediate (DI) process, the low quality output of the telecines was replaced with the dramatically higher quality output of DI scanners (e.g. the Lasergraphics Director 10K, ARRISCAN, Northlight, etc.). The far superior data files generated by these scanners turned the real-time video world on its head. No longer constrained by real-time all-the-time speeds, the DI scanners were finally able to strike a balance between reduced scanning speeds, increasing image quality, higher resolution, lower digital noise, and rock solid image stability.
Three scanners revolutionized film output quality by slowing down the DI scanning process to less-than-realtime! The Northlight, scanning at multiple seconds per frame, was heralded as a miracle for visual effects. The ARRISCAN (at 4 to 8 frames per second) and the Lasergraphics Director (at 10-19 frames per second) quickly became recognized in Hollywood and around the world as technical innovation that was tailor-made for DI. Indeed, the DI scanners were the final nail in the telecine coffin.
Telecine Images are Unstable
All telecines use “edge guiding” by which mechanical edge guides keep the film registered in the gate.
Film Aligned to Edge Image Sensor Aperture Typical Telecine Gate
However, motion picture cameras do not use the edge of the film while exposing. Instead, they rely on the film perforations for stabilization. Unfortunately, the spacing between the edge of many film stocks and the perforations has not historically been well controlled by film manufacturers. The SMPTE 93-2005 specification for 35mm film dimensions allows for a margin of ±2 mils between the perforations and the edge. This corresponds to an error of ±4 pixels at 2K resolution.
Film scanners that directly use the perforations of the film to separately align each frame greatly improve alignment accuracy – down to approximately 1/5 of one 2K pixel. This represents a 20x improvement in stability compared to edge-guided telecines and telecine-like scanners.
Mechanical Pin Registration
Mechanical pin registration works adequately for stabilizing new film but futile for old damaged, shrunken or warped film. This is because an old piece of shrunken film can be easily pierced or torn by the pins as it moves through the gate. Modern film scanners optically sense one or more perforations on each frame in order to stabilize the image, a process known as optical registration. Optical registration is vastly superior to mechanical pin registration in every measurable way – it enables gentle film handling while improving image stability!
2D Optical Registration
Lasergraphics scanners are highly immune to perforation damage and splices while maintaining precise registration. Lasergraphics’ proprietary 2D optical registration system detects the location of up to 8 perfs per frame and then determines which, if any, are damaged. The damaged perfs are ignored while the undamaged ones are used to align the image – the frame is stabilized along the X, Y and rotation axes even if only one of the perfs is usable. Incredibly, this happen in faster-than-realtime with some Lasergraphics scanners — up to 60 frames per second! Therefore, shrunken and/or poorly spliced film can be effectively stabilized during the scanning process with no mechanical or software adjustments, eliminating the need for post-scanning stabilization.
- Mechanical pin registration, which engages the film in only two perforations and is only effective on undamaged and non-shrunken film.
- Edge guiding, which weaves laterally because it entirely ignores the holes and is highly intolerant of splices.
Telecines are Splice Intolerant
Edge-guided telecines and film scanners can not handle splices well. Splices cause a lateral shift in the image position when they touch the edge guide, which in turn creates lateral color shifts in the image:
Optical pin registration eliminates the film registration problems caused by film splices:
Telecine Images are Susceptable to Banding
Telecines and telecine-like scanners move the film continuously past a thin aperture, corresponding to its line image sensor. As a result, dirt builds up in the line aperture during scanning. The dirt that accumulates in the scanning aperture blocks some of the light in subsequent frames. This causes subtle intensity differences which appear as banding in the image.
For area imagers, this dirt typically remains outside of the active image area because the scanning aperture is oversized.
For modern film scanners, this dirt typically remains outside of the active image area because the scanning aperture is oversized.
Telecines Can’t Detect and Eliminate Dust
Film scanned on a telecine invariably contains dust in some frames and has no means of automatically detecting or eliminating these defects.
The Director 10K film scanner incorporates infrared dust and scratch detection which works during scanning to detect and reduce dust and surface scratches without softening, blurring, or altering the image. A defect map is generated, depicting pixels that have been automatically corrected plus defects that require additional attention (if any). The defect map allows the operator to easily locate the defects and correct them as a post process.
Telecines Can’t Handle Warped Film!
Film cannot lay flat on a Telecine Film Gate, resulting in bad focus:
The Director 10K Film Gate holds warped film flat on all 4 sides with a pressure plate for superior full-frame uniform focus: