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First Draft of Archival Film Scanner Technical Specifications
First Draft of Archival Film Scanner Technical Specifications
The Pixel PERCEPTION FILM RESTORATION & PRESERVATION SCANNER:GENERAL INFORMATION:This custom designed Film Scanner was created specifically with the Archival &Restoration Community in mind. Unlike typical scanners, all design constraintswere weighted toward quality and safety, rather than the speed of imagecaptures or film transport.The Pixel PERCEPTION FILM RESTORATION SCANNER has a unique set offeatures and capabilities that set it apart from virtually all other commerciallyavailable Motion Picture Film Scanners, including those that offer so-called‘Archival Packages’.This system combines the ‘Best Of Both Worlds’, drawing upon time provenanalogue Optical Bench and Optical Printer technologies, which are then digitallysupplanted and extended to achieve the highest quality digital captures fromarchival film elements.
SCANNER OPTO-MECHANICAL CONFIGURATION:The CCD camera is permanently mounted at one end of the optical positioningtrack for maximum stability, and isolation from mechanical vibration. The lenstable is used to control image sizing and position. The projector system table isthen used for critical focus and final image sizing. Optical, rather than DigitalEnlargements and Reductions, including extremes of these two options areeasily accomplished with this system.Further film safety is engineered into the film transport system via theimplementation of a horizontal film transport, as opposed to the traditionalOXBERRY vertical orientation. This configuration greatly reduces a variety ofload forces on the film, which results in greater film element safety.
STEPPER MOTOR MOTION-CONTROL SYSTEM:All imaging components of the system are positioned using microstepper motioncontrol.The softwares open design enables the rapid creation of custom commands andintegration with external DOS machine control programs, which greatly extendsthe command set. This allows virtually unlimited customization of the machinecontrol software to meet changing, or evolving, client and operator needs.Combined with the precision mechanical apparatus, this system offersexceptionally fine micro positioning of the main imaging components, offeringextremely flexible solutions for adding additional features or proceduralprocesses.The integral Motion Control Positioning software allows the operator to save, andrecall, a precise ‘snapshot’ of all component positions. This allows for rapidreconfiguration of the lens-board and projection systems. This also allows for thecreation of position presets to move the components to the proper coordinatesfor a given format. This feature adds greatly to the speed of reconfiguration ofvarious scanning formats.
THE PIN REGISTERED FILM PROJECTION SYSTEM:The Pixel PERCEPTION Scanner features an OXBERRY based Film Projectionsystem. Although highly modified and modernized, the heart of the projectorsystem is based on the industry standard, and century proven, OXBERRY pin-registration film movement and shuttle technologies.A wide variety of pin-registered film movements, and transport sprockets,augment the capabilities of this machine. A small sampling is shown above.Included are specially manufactured movements that are configured withshrunken and/or offset pins used in conjunction with modified interchangeabletransport sprockets. These are used to safely transport shrunken film that hasvariations in perf to perf pitch, and/or irregular ‘shrunken’ perforation dimensions.VISTAVISION 8 PERFORATION 35mm SCANNING:This system is very well suited to scanning any format that fits into the 8-perforation aperture and a wide variety of both 2 and 3 pin movements areavailable, in Positive and Negative Pin configurations. (8-perforation Liquid gate scanning is also available).
FILM TAKEUP AND TENSION CONTROL SYSTEM: The traditional OXBERRY Film Takeup and Tensioning system has been replaced by a significantly more sophisticated design. An innovative combination of viscous damped rollers and ‘tunable’ spring balanced tension transport roller assemblies, shuttles film with a minimum of axial tension, or ‘Poisson effect’, which eliminates the usual filmstrains encountered during the startup and stopping of film transport. This takesplace during slewing as well as during frame-by-frame advancing during thecourse of actual scanning.The film Take-up Motor System uses an improved version of the traditionalOXBERRY pulley and shock-absorbing drive band technology that allows forprecisely tuning the torque cushioning during film startup and completelyeliminates the need for clutching or braking mechanisms common withservo/stepper takeup designs..FILM PLATTER CAPACITY:Film platter capacity has also been increased, to handle oversized rolls up to2500 feet in length (3000 feet on Estar polyester based stocks).The Take-up tension and Back-tension intensities are individually set, and arereversed gently when the film transport is reversed; insuring that minimal filmstresses, smooth winding, and appropriate roll wrapping tensions are alwaysmaintained.
MULTI FILM WIND FUNCTIONALITY:Special switching circuitry allows the operator to set the direction for each platterallowing for any ‘A’ or ‘B’ wind orientations and transport direction of film scanelements. This is especially useful when scanning 16mm single perf stocks, andfor reversed or inverted image elements made with specialty lenses or footagefrom cameras such as high-speed prism or reverse wind animation cameras.PROJECTOR FILM TRANSPORT SYSTEM:The Projector transport is stepper motor driven. This allows for extremely smoothacceleration and deceleration of the film, and insures that the film is absolutelystationary on the registration pins, prior to initiating the exposure cycle.This Scanner shuttles fragile and damaged archival elements at a relativelyslower speed than traditional scanners to further minimize any strain due tosudden tension or direction changes. These accelerations and velocities are alsoeasily tuned to match the characteristics of specific film elements. This insuresthat all film is gently treated, perforations are unstressed, and that vintage splicesare not subjected to the high stresses associated with most other machines usedfor motion picture scanning.INTEGER ‘SKIP’ AND ‘STEP’ FRAME RATIO SCANNING:Integer ‘skip’ and ‘step’ frame ratio imaging is included in the software features.This allows for VistaVision scanning, and also offers the option to scan sectionsusing skip-frame (Scan every nth frame only) and step-frame (scan whateverframe nth number of times).
LIQUID GATE and SOFTWARE DIRT REMOVAL TECHNOLOGIES:The Oxberry liquid gate is an Academy Award-winning pin-registered filmmovement that submerses the film frame in an optically clear liquid during theimaging process. The liquid, contained between optically flat, clear water-whiteglass windows, is constantly circulated with a pump and vacuum system. Thisliquid has the unique characteristic of a comparable index of refraction to that ofthe film base. Film immersed in the liquid has its base scratches, ‘digs’ and othersubstrate imperfections filled in during the period of imaging, making theimperfections invisible to the camera. All base scratches and certain types ofemulsion side scratches are thereby eliminated as the film image is beingscanned.This system uses OXBERRY liquid gate technology. A modified vacuum and fluidpumping system is used to properly support this process with the projector in thehorizontal orientation. At normal operating speeds the higher vacuum capacity, inconjunction with the projector airflow system, insures that film emerges virtuallydry from the movement. Film is never ‘wound wet’ at the take-up platter.
LIQUID GATE PROCESS TECHNICAL DESCRIPTION:Liquid Gate technology hides scratches and defects that have not intruded intothe color layers from being reproduced when the film original is scanned.Scratched film causes the light rays to scatter creating variations in imagedensity under specular illumination (Fig. 1). The scattering effect of a scratch dueto the difference in refractive index of air and film is shown in the drawing. If onefills the scratch with a material that has the same refractive index as the film, thenthe scratch will not show.In liquid gate scanning, the film moves through a liquid-filled glass envelopemounted in the film registration movement (Fig. 2) at time of exposure, filling inany scratches and preventing refracted light from reproducing them in thedigitally captured image. This provides universal density transmission across theentire scanned image area.POSITIVE PRESSURE IONIZED AIR SYSTEM:Another special feature of this system is the sealed film projector. This systemincorporates a Positive Air Flow system that fills the film chamber withelectrostatically ionized air as part of a triad of dirt, dust and particle removalprocesses. The high voltage negative ion generator and air pump provide bothair purification and particle removal from the film by changing the electricalcharge of dust particles. This causes particles to lose their static charge andeliminates their ability to adhere to the surface of the film, prior to reaching thescanning aperture. A HEPA filter at the air intake port keeps dust from beingintroduced into the system and a foam filter at the exit port eliminatesreintroduction of accumulated dust into the scanning environment.No Ozone is generated by the ionization system. This insures that no chemicalchanges or degradations are added to the film emulsion or its substrate, whichmight otherwise lead to film discoloration, fading or damage to the film baseitself.
PARTICLE TRANSFER ROLLERS:The dirt removal process is enhanced with numerous Particle Transfer Rollersand a proprietary integrated software based DRS system. When these systemsare used in conjunction with the Liquid Gate technology, the result is extensivedust and scratch removal at the point of scanning.The software also allows for the creation and retention of an additional alphachannel dirt & scratch map that can be used by external DRS technologies suchas MTI, etc. for even greater image correction flexibility.IMAGE REPRODUCTION OPTICS:The Imaging Lens is one of the finest lenses ever manufactured by Nikon. ThisThe Copy Lens is a 14 element, 6 group, multicoated 150mm f/2.8 Printing-Nikkor lens that was specifically designed for 1:1 copying of motion picture filmstocks. The lens has a legendary reputation. it has the highest resolution andcontrast of any lens in its class. This model of Printing-Nikkor lens fully maintainsoriginal image fidelity of motion picture film.
The actual lens used in this system is the last generation of the 150mm Printing-Nikkor. This versions resolution was increased from 200 line pair per mm to 240in the center (1/1X) of the image, and from 150 line pair per mm to 180 at theedges.The ‘Image Circle’ of this lens is 88mm, roughly 3.45 inches, in diameter allowingoptimum reproduction of all 35mm formats, including 8-perforation VistaVision,and is also sufficient for scanning 65/70mm elements without edge vignetting.Nikon specifications for this lens are 0.0000000000% Vignetting, and Distortionof 0.0000% when focused at 1:1, at f/4.0 aperture. This lens was selected from adozen of the same batch. All were tested on an optical bench to determine theoptimum lens for this machine.This lens is truly apochromatic. This Lens virtually eliminates chromatic aberration,which is specified at 0.0% in the ‘visual’ range of 400 to 800 nanometers. It has also beendesigned to virtually eliminate all optical aberrations, such as spherical aberration, whichfor this lens is specified at 0.00001 %.IMAGE SIZING and POSITIONING FLEXIBILITY: Image Sizing and Positioning are highly accurate, and accomplished entirely through optics, without any digital manipulation, or transformations, which could add averaging or other digital artifacts. A Motion Control OXBERRY Lens- board offers precise control of the lens X-axis and Y-axis positions for exact image positioning. ‘AAAO’, or ‘Academy Aperture Area Only’, scanned images can easily be created, via optical repositioning, and exported at full 2k, 3k or 4k widths for maximum image resolution. This is especially useful when correcting misregistered colour records or for post scanning software mesh corrections of intra frame distortions of individual colour layers.
Additionally, this system allows for extreme enlargements, reductions andprecision, customizable extractions from any format supported. This featureallows for very high accuracy 1:1 capture of frames. After adequate testing, thisfeature offers the ability to correct for some degree of Colour Separation masterX, Y and Z dimensional shrinkage or misregistration during initial scanning,although this process is best accomplished as a post-scanning process.The focus system uses a 10:1 combined gear ratio, achieved by a combination ofgear reduction pulley and belt drive with a 5:1 transmission at the stepper motor.This results in extremely precise image focusing.The scanner application tools digitally output visual and graphical focus data inconjunction with the operator visually verifying grain focus while rapidly firing thecamera and illumination system for near-realtime focusing at an extrememagnification display size.Scaling software is also included to allow for a variety of 1:1 native, upsampleand downsample scaled images using rapid and intelligent software kernels andalgorithms.EXTRACTIONS, 3K 1:1, OVERSAMPLED TO 2K, OR SCALED TO 4K:The most common operation of the scanner involves scanning a full-aperture35mm 4 perforation frame to machine-native raw images at SMPTE spec 3k(3072 x 2304) and then internally scaling the final output image up to of 4k (4096x 3072), or down to 2k (2048 x 1536).2.35:1 or 2.40:1 anamorphic extractions, ‘Common-Top’ or ‘Common-Centre’,can easily be made from 3 or 4 perforation 35mm elements and from Super-16mm elements of sufficient image quality.These optical extractions can be exported as spherical (Flat) 2048 x 872, etc. ordigitally non-proportionally scaled anamorphically (Squeezed) at the point ofscanning.
THE ‘TUNED-PULSE’ LED ILLUMINATION SYSTEM:The Pixel PERCEPTION proprietary ‘Tuned-Pulse’ LED Lamphouse allows forgreater exposure consistency over incandescent illumination devices, without theneed for a feedback loop and circuitry to attenuate the lamp. The Light EmittingDiodes were custom manufactured for this device. They were designed to matchthe narrow band characteristics, and specific wavelengths, of traditional opticalsystems using Wratten Gel or Corning Glass colour separation filters. Thiscreates scans with less colour crossover, greater colour purity and greater easein restoration of original colour values. The Integrating Sphere LED Lampsystem covers formats from 8mm to 65/70mm, using an extremely flat field ofillumination from a specially textured target designed to slightly diffuse light raysto help de-emphasize film grain in the final scanned images. The Lamphouse canalso be rotated 90 degrees to cover VistaVision, 65mm / 70mm or IMAX formats.The LED illumination system also creates no heat at the scanning aperture whichmakes it ideal for scanning heat sensitive elements, including Nitrate basedvintage stocks. The main advantage of this cold illumination technology is that itvirtually eliminates film ‘popping’ in the aperture - intra-frame distortions includingminute changes in focus and size that are often present in incandescentillumination systems. This is extremely important when scanning colourseparation masters for re-registration during digital recombining. This featurealso eliminates the risk of increasing fading on marginal, or already faded,scanning elements.MULTI EXPOSURE MODE FOR HIGH DYNAMIC RANGE ELEMENTS:This exposure mode captures separate low and high density passes by exposingthe film multiple times, at multiple offset LED exposures for each colour channelexposed. This software feature combines the successive exposures to capturethe full, or extended, dynamic range and to maximize the signal-to-noise ratio inthe final output image. This system is currently under development and variationsusing as many as four separate exposures are being investigated. Trials using awide variety of data merging algorithms are also currently in progress.
THE CCD ARRAY CAPTURE CAMERA SYSTEM: The overall system was mechanically designed with an easily interchangeable camera mount which allows for adding virtually any CCD array capture camera to be mounted for experimental testing and/or use. The current image capture camera is an Atmel-Thompson Camelia High Dynamic Range 12-bit Linear Monochrome CCD Array Camera. This CCD camera has an Image Format of 35.0 mm (V) x 23.0 mm (H) and Pixel Geometry of 10 µm x 10 µm, with an aperture ratio of 100%. This High Sensitivity Full Frame CCD Sensor very closely approximates a 1:1 size ratio with 35mm motion picture film, to maximize the efficiencies of the Optical system characteristics.This camera features a 63 dB Signal to Noise Ratio that produces images withvery low digital noise. Combined CCD Defect mapping, Darkfield BalanceMapping and Flatfield Correction Mapping, insures a pristine and non-artifactedimage capture. A 12-bit to 12-bit LUT (Look Up Table) applied at the output of thedigital frame grabber provides excellent colour fidelity in either Linear orLogarithmic Colourspaces. This camera has precise R.O.I. (‘Region of Interest’)settings, which allow exact sizing of exported optical extractions.Tri-colour (successive individual RED, GREEN and BLUE) exposures are madeof each colour layer and are then combined in software as full colour images forexport. This mimics the colour separation process digitally, and also allows forcorrect wavelength exposures of existing Colour Separation Masters.In 3 shot the LUT and exposure times can be programmed separately for the red,green and blue color.Scan elements that are monochromatic can be imaged in single colourillumination mode, using any of the three colours desired. Green is most oftenused due to its greater luminosity. The final image is always monochromatic, butthe choice of illumination colour can be used to alter or enhance the contrastrange of certain film stocks.
CAMERA CHILLING FOR MAXIMUM STABILITY and CONSISTANTCY:The CCD Camera is further controlled by external solid state Peltier JunctionThermoelectric Cooler, which greatly increases the stability and consistency ofimage deviation parameters.CUSTOM LUT CREATION TOOLS:Proprietary LUT creation and modification tools insure that all information fromthe original scan element is captured and stored digitally. These tools allow forcapture of the maximum colour information from all elements and specializedcolour corrections for restoration of lost or faded colour information.ADDITIONAL POST SCAN IMAGE PROCESING SOLUTIONS:When combined with the post-scan image processing software, innovative colourreconstructions, as well as hybrid or synthetic colour layers can be created.
INTEGRAL SOFTWARE APPLICATION and OPERATOR INTERFACE:The scanner machine control, image acquisition and processing software are allproprietary. The software package offers a myriad of feature combinations andflexibilities not found in other systems. The software application, which isconstantly evolving, continues to bring greater speed, flexibility and functionalityto the system. The current version of the software allows many previously ‘post-scan’ processes to be performed at the point of scanning, to greatly reduce postscanning workflow and downstream processing costs.Scanned images can be directly created in the following formats: 12-bit .J12, 10-bit log .CIN, 10-bit log .DPX, and 8-bit or 16-bit linear .TIF files.During post scan image-processing, images can be converted to virtually anyformats including, but not limited to; 10-bit log or linear .SGI, 8-bit or 16-bit .PSD,8-bit .JPG, 8-bit .TGA, JPEG 2000, and many more.
(Copyright 2001 – 2011) Pixel PERCEPTION / C. Dusendschon All Rights Reserved