The DRA Method

1st September 2015
The Digitally Restored Authorizate method (“DRA”)
represents the working procedure used in digitization of the national film fund with the aim of restoring a film work so that the appearance of the image and sound component of the digitised film print is as close as possible to the original author’s concept of the film work as first presented at its première.


The age of digital technologies has given origin to a cardinal problem that affects the current practice of film restoration and fails to be addressed by any of the codes of film archiving of the past.


This problem consists of an evident conflict between the opinion that the personalities representing the archive have in terms of what the appearance of the digitised film prints should be like and the interest concerning the appearance of the digitally restored works on the part of their authors. It can be demonstrated by recent experience from presentations of digitised film prints that the interest of the authors of the works does not differ from that of the audience although this audience lacks professional erudition in terms of technologies. The archivists’ interest is satisfied by their digitally documenting the current condition of the works in their analogue form, irreversibly impacted by devastating physical and chemical changes. Authors and, clearly, spectators themselves have no reason to accept this age-degraded form provided that it can be avoided in today’s digital age. For authors, such digital appearance is an insult and shame; for a paying audience, it represents unfulfilled expectations. Both authors and spectators are interested in as true digital restoring as possible the objective of which is to restore the original appearance of the work. It is therefore also an ethical question whether the above mentioned devastated form should be forced upon them if we have available means and procedures guaranteeing the preservation of the original visual and acoustic quality of the work – the DRA (Digitally Restored Authorizate) method.


Since restoration is an interpretation of the original appearance of the film, an expert restorer should competently analyse the initial resources and properly diagnose their frequently poor quality. Not everybody is able to perform an analysis and diagnosis of defects in a competent manner. Besides various experts, what is usually required is a trained professional cinematographer with extensive experience. Such cinematographers are organised in a professional association whose competency is to supervise the preservation of image-related values ​​of cinematographic works created by the authors of such works. Such professional supervision has been fully applied since the origination and initial development of the DRA method and the achieved results of the first digitizations document its importance.


The DRA method strives to create new digital prints using the original negative. Just as an analogue film print once used to be made from the original negative, today, an additional new digital print may originate. A restorer is responsible for ensuring that a new version of the work does not emerge and is the guarantor of this even in the case of authors who do not live anymore.


It is pointless to talk about improving or failure to improve in the process of digital restoration because image information contained in the original negative transferred by being scanned into digital files brings a completely new qualitative benefit in respect to the degraded print even without intentional interventions of restorers and their expert groups or of authors, if these are available. Furthermore, it should be noted that the inevitable amount of image-related damage due to ageing is compensated by digitisation in the sense of returning the image to its original appearance which cannot be considered improvement. Rigid insistence on digital fixing of a poor quality print under false pretence of so-called authenticity renders an ill service to cinematography as a performing art. The current digital era obliges both filmmakers and archivists to revise such notions of authenticity and to condemn them as worthless from the point of view of preserving cinematographic works for future generations.


That is why the DRA includes the word “Restored” in its title.


DRA stands for: D – Digitally, R – Restored, A – Autorizate (Authorized as the original source)


The DRA method uses the work of a professional restorer, university educated in cinematographic audiovisual crafts, capable of putting together a professional expert group enabling  him/her to a qualified dialogue over the work and providing him/her immediately with valuable expert opinions. Since each restoration work is an activity involving both artistic and interpretational skills, a restorer must be capable of making educated guesses as well as of the required image and sound related interpretations.


The authority of such an expert must be supported also by the appreciation and confidence expressed by the specialists in artistic disciplines participating in the restoration process. These are for example professional associations of authors that consist of the finest artists of the given field. What it mainly involves is the image (cinematographer), sound (sound engineer) and direction (director). Only then can a restorer embark on the serious work of restoration.


The DRA method originated during cooperation of archivists and cinematographers on the digitisation of the following films: Marketa Lazarová, The Firemen’s Ball, All My Compatriots and Closely Watched Trains. In its definitive form, the DRA method was used when restoring the film The Stone Bridge when it was allowed, for the first time, to declare this fact by stating the names of the restorer and the members of his expert group in the credits. All these cases of digitization have been recognized as outstanding by the professional community.  In this way, the accuracy of the DRA method was demonstrated. The method is the result of the NAKI research project No.: DF13P01OVV006, undergone at the Academy of Performing Arts in Prague in collaboration with experts from the Czech Technical University.


The DRA method comprises the following steps:


  1. Commencement of work on digital restoration – selection of a film, determination of the producer of digital restoration, responsible search for funds sufficient to initiate restoration works.


  1. Appointment of the chief restorer of the digitization project who will follow the DRA methodology and bear the main responsibility for the results.


  1. The restorer will put together an expert group in line with the DRA methodology. It will include experts from among film historians, film technologists, film restorers working with analogue archival documents, three experts – professional cinematographers, two experts – professional sound engineers, a supervising film director, head technologists of digital departments, a representative of the respective state authority or a representative of the entity that ordered the restoration work.


  1. The restorer and the expert group will choose from the surviving prints the one that is the closest to the original appearance of the film. Film prints age faster than negatives and, given that in former Czechoslovakia, the so-called “signed prints”, i.e. prints from the première of the film, failed to be archived; this selection is a very difficult but, at the same time, a very important step. Researchers working under the DRA methodology have previous experience in making an absolute essential selection of surviving prints which can serve as a reference, based on professional cinematographers’ discretion.


  1. Selection of reference sample scenes. In compliance with the DRA methodology, typical scenes from the film are selected, which the expert group will analyse. The darkest scene, the brightest scene, an average scene, daytime atmospheres and non-daytime atmospheres, etc. According to the methodology, there are six sample scenes + three optional ones, as per the restorer’s requirements. Their combined total length is about 12 minutes.


  1. Samples from the positive film print are scanned at 4K resolution and colour graded as an accurate facsimile so that no ordinary spectator can recognize whether it is a film print or its digitized print. Its current condition is respected, whatever it is. This is a so-called DFRRP – Digital Facsimile of Reference Release Print. This facsimile is a working tool for the restorer who later compares it with the information provided by the positive image of the scanned original negative.


  1. Scanning of the negative also takes place in 4K resolution, in order to preserve image information carried by the negative. The restorer’s estimate, the so-called EGAP – Educated Guess of Answer Print, is the interpretation of the appearance of a print altered by age given what is offered by the original negative. By comparing the DFRRP and the scanned original negative, DSM – Digital Source Master, which are already projected using a single digital projector on a split screen, the main restoration work takes place, consisting in a search for the original appearance of the image corresponding to the author’s concept of the work. It is therefore possible to immediately assess and evaluate the restorer’s estimate. This is the most important phase of the work of the restorer and his/her narrow expert group composed of invited cinematographers. The DFRRP and the DSM prepared based on the original negative leads to the EGAP – Educated Guess of Answer Print. If the EGAP has been set up correctly, the DRA originates. The work process with the sound is similar.


  1. In the meantime, the so-called “cleaning” of hairs in the gate and repairing of damaged parts of the film, as well as tracing of missing video and audio sources take place. Now is the time for historians’ detective work.


  1. In the meantime, a digital colourist works on colour grading and reconstructing the film’s appearance independently, using the DRA samples as reference. Once the digital colourist’s work is complete, the restorer comes back with his/her expert cinematographer group and they further correct the digital colourist’s work when the complete work is presented. This saves a considerable amount of time and funds. The final appearance of the film is discussed with the restorer and the expert group. It is subjected to final modifications and approved. This is how the DRA, a new digital print of the complete work, emerges from the original negative which can be considered a new original source of the given film. The DRA is by no means a new version of the film.


  1. Completion and exporting of the resulting DRA data as a master. The DRA must also contain further removable artefacts such as hairs in the gate, cue marks of individual film reels, if such cue marks were punched out on the negative, as well as all camera apertures and formats that were used when filming using multiple cameras. The DRA is the original source and therefore it must necessarily include all these elements. The DRA having this property is rightly regarded an ideal archival material as it suits the interests of archivists, historians and authors. It compensates defects of the negative or other original sources caused by their ageing.


  1. Production of the DCDM – Digital Cinema Distribution Master – for further distribution of the film. This data file no longer contains any visible hairs in the gate or any projection cue marks of film reels. It is assembled and respects the uniform projection aperture from the time when the film was made. This DCDM is further used to manufacture all distribution masters. However, the DCDM contains basic information about the appearance of the DRA master. It is thus the DRA converted into a source designed for distribution and it is thus necessary to state this fact in the opening and credits of the film along with the information on who was the restorer and who were the members of the restorer’s expert group.


  1. Storing the DRA is performed using a chosen procedure. The DRA can be stored on hard disks or disk arrays in the form of an MAP – Master Archive Package, which is a mathematically lossless format JPEG 2000, also as the DCDM in the IAP – Intermediate Access Package form (mathematically lossy but visually lossless format JPEG 2000). Another way to store the DRA is on film stock either as an NON – New Original Negative, which is a cinematic image and sound laser-recorded back on a film negative, or as an SPM – Separation Protection Master. This means to print the image into three black-and-white negative strips carrying information on the colour components (red, blue and green) of the image. Each of these black-and-white separate negatives have a longer life than a colour negative film. When the developed film is stored well, its life is in the order of several hundred years. This is probably the most reliable practice used in American production studios. Today, it is possible to store cinematographic digital data even in a numerical format directly onto a filmstrip using the form of the DAN – Data Archive Negative. However, this method remains unresolved due to its capacity and the amount of filmstrip used. In principle, a new archival medium is expected to arise in the future that would archive data and would not be subject to the ravages of time.


The DRA Method CHART:

AP – Answer Print — is the final print of several carefully approved Trial Answer Prints (First, Second, …) processed by a Cinematographer in a film laboratory usually printed directly from the composited camera negative. The Final Answer Print is also known as a “Show print” used for screening at special events such as gala premieres. It is, at the time of the film’s origin, a balanced, so-called “signed” release print containing synchronised visual as well as audio components, approved by the cinematographer, sound engineer and director of the film, who all physically signed its first reel, presented at the première of the film and is generally used later as the only authoritative reference material for producing new prints. Today, it is suitable as a reference for digital restoration. This rarely occurs in the Czech Republic but is a standard practice westward from our borders.


RRP – Reference Release Print – a print carefully made at the time of its origin, a balanced print containing synchronised visual as well as audio components, intended for distribution in cinemas. It was chosen as a reference release print by the restorer, i.e. as the one closest to the signed print. It is always an estimate which is why the selection of the reference release print must be carried out together with the expert group consisting of cinematographers.


DFAP/DFRRP – Digital Facsimile of Answer Print or Digital Facsimile of Reference Release Print. This facsimile is an exact replica of the heritage item or of its part, identical to the original in shape and colour, different by the technology and material used. The facsimile captures the current condition of the work including traces of its development in the course of the time (damage etc.).


DSM – Digital Source Master – is a proprietary set of digital video and audio files created in the post-production process, depending on the processor of the cinematographic work and on the technical facilities available, i.e., e.g. data from a film scanner. The set includes uncompressed and unencrypted video, audio and subtitle files, compliant with the relevant international standards (e.g. ISO 26428 and recommendations of the SMPTE), stored in TIFF files with a bit depth of 12 bits or 16 bits per channel. The picture is saved with the camera gate, cue marks of film sections and does not have retouched hairs in the gate or material damage.


OCN – Original Camera Negative – the negative originally exposed in a camera.


DP – Duplicate Positive – Master Positive (MP). The same black&white or color timing used to create the final Anwer Print (AP) is used to print a Master Positive.


DN – Duplicate Negative – Dupe Negative (DN). A negative black&white or color copy made from the Master Positive (MP).


IM – InterMediate – Intermediate Film Stock with an average gradient of ɣ = 1.00 used for printing color Master Positive or Dupe Negative.


SP – Silent Print – a film print without the sound track.


PMP — Protection Master Print – a “Master Print” made from the OCN and SNN, containing synchronized visual and audio components, serving as a backup in case of a loss, damage or fading of the OCN. These prints are stored in the archive and are never lent for screening.


OST – Original Sound Track – original soundtrack of the cinematographic work is recorded on magnetic or optical media and used as authoritative reference material for digital restoration.


SNN — Sound Negative — sound negative is the original soundtrack recorded in an optical form or a transcript from the OST into the optical form used in the production of RRP, RP, SNP or PMP, produced in a sound camera.


SNP – Sound Positive – independent positive print produced from the sound negative for the purposes of subsequent digitisation. A positive sound print is usually a new film print carefully made from the SNN with one-sided or double-sided optical recording of the sound which does not contain the image component which is complete compared to the SNN.


RP – Release Print – a release print is a print of the film carefully made from the OCN and SNN intended for screening in cinemas, containing synchronised visual and audio components, which is, at the moment of digitisation in very good technical condition.


EGAP – Educated Guess of Answer Print – the estimate made by the restorer and his/her expert group of the basic image parameters (brightness, contrast, hue, saturation) aimed at restoring the original appearance of the signed (reference) print at the time of its première. This estimate made by the restorer is based on a scanned negative of the image (or the closest surviving source of the film’s image) and on its being compared with the Digital Facsimile of Reference Release Print, the DFRRP.


DRA – the Digitally Restored Authorizate – is the result of a process of digital restoration (modified DCDM with a camera gate and without retouching) which has been certified by the restorer, the expert group and representatives of the state authority as the new original source of the original work. The DRA thus cannot be considered a version of the work but its original digital source.


DCDM – Digital Cinema Distribution Masterare uncompressed and unencrypted video, audio and subtitle files complying with the respective international standards ISO 26428 and recommendations of the SMPTE, stored in TIFF files with a bit depth of 12 bits or 16 bits in the XYZ colour space as the digital original designed for distribution. The image is stored with the projection image area from the time of its origin, retouched cue marks of film sections and retouched hairs in the gate or material damage.


IAP – Intermediate Access Package – is a set of unencrypted, compressed video and audio files, identifying complementary technical metadata and media (visually lossless compression of the visual component, audio component without compression) created from the DRA (in the form of the DCDM); it is intended for production of all distribution formats (for digital cinema, television, home video, web etc.). It is not suitable for long-term storage of cinematographic works, it contains only the projection image field and supports only frame rates according to the relevant international ISO standard for digital cinematic projection. The DRA product optimised for creation of additional sub-masters for distribution exploitation (DCP, DVB-T, BRD/DVD, VOD, etc.).


DCP – Digital Cinema Package – is a presentation print for distribution in digital cinemas; generally, it is not suitable for long-term storage of cinematographic works.


DAP – Distribution (Dissemination) Access Package – is any distribution format (for digital cinema, television, home video, web, BRD, etc.)


DVD – Digital Versatile Disc (Digital Video Disc)


BRD – Blue-Ray Disc


VOD – Video On Demand


HDTV, UHDTV (UHD) – High-Definition TeleVision, Ultra High-Definition TeleVision


MAP – Master Archive Package – is a set of unencrypted, compressed video and audio files, identifying complementary technical metadata and media (mathematically lossless compression of the visual component, the audio component without compression) created from the DRA (16-bit TIFF, XYZ) in an arbitrarily selected resolution, intended for long-term preservation of cinematographic works; it should contain the whole camera image field (incl. any optical sound recording, perforation holes of the filmstrip etc.) and support the original projection frame rate. The DRA product optimised for long-term digital preservation.


DAN – Data Archive Negative – is the data entry into the film negative (Data Archive Negative).


NON – New Original Negative – was created by laser recording of digital data into a new negative film stock where it produces an analogue cinematic image.


NAP – New Answer Print – a print made in order to check the New Original Negative – NON.


SPM  – Separation Protection Master – three black-and-white separation R, G and B colour extracts from the original colour negative or the DRA used for long-term archiving of the three black strips “R”, “G” and “B” made by printing or laser recording onto a durable archival black-and-white negative with the gradient of ɣ = 1.00.




The Digitally Restored Authorizate (DRA) can be considered the original source of a film work only if it meets the following criteria:


1)   The image is digitised in resolution corresponding to the original film stock + in the original frame rate + in the aspect ratio and image size corresponding to the original + with the sufficient luminance range and colour depth of the image faithful to the original;


2)   A professional workplace of officially recognised expert film and digital restorers or such restorers that are university educated in the fields of cinematography and sound engineering participated in the restoration of the film;


3)   Authors of the film participated in the restoration of the film – cinematographers, sound engineers and directors (if available) and representatives of their professional associations of authors;


4)   The restored film is approved by an expert group consisting of restorers and authors (officially recognised film restorers, the aforementioned authors of the cinematographic work if they are available and representatives of professional associations of authors) whose members should sign, after mutual consent, an official certification document on the DRA and/or a restoration report documenting that the DRA method was used;


5)   Differences in quality between AP, RRP or DFRRP and DRA, as far as the appearance is concerned, must be executed, in order to preserve the author’s concept of the film work – within the meaning of the Copyright Act, based on an informed estimate of the expert group;


6)   What is used as the single source for archiving the DRA is the so-called Master Archive Package (MAP) and the Intermediate Access Package (IAP) from which, subsequently, all the copies of any distribution formats (digital cinema, television, home video, web etc.) are made, namely without any intervention into the appearance of the work as per the above-defined criteria (except for changes in the overall size of the image and the different levels of compression depending on the respective distribution format).


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Contact address:

Academy of Performing Arts in Prague

Malostranske namesti 259/12

118 00  Prague 1

Czech Republic



Contact person:


Prof. MFA. Marek Jicha

+420 723437344

head of researching program NAKI AMU No.: DF13P01OVV006


Prof. MFA. Jaromir Sofr

+420 732192433

member of researching program NAKI AMU No.: DF13P01OVV006