Quality Checking
Introduction
The end product of a restoration project is a piece of film, ten reels long or just a few metres. Whatever the length it has to be suitable for the purpose, and the best visual quality obtainable from that original. In most cases the film is intended for either optical projection or for video transfer and these two purposes may result in two different results.
The major problem with all archive film conservation and restoration is that today we do not project film using the same projectors the same light sources onto the same screens as was done in the past. Since much of the oldest film that needs to be preserved is in the last stages of decomposition the quality obtainable will be quite low, and from this film it is essential to be sure that the result obtained is the best possible from that original.
Thus, the first problem facing a Quality Checker is the definition of Quality.
The objective in assessing modern film quality is always to achieve a print with good gradation that has the least visible grain possible and is as sharp and has the highest quality sound as the film stocks used will permit. Defects should be at a minimum. To able that philosophy to a wide range of archival films covering 100 years of film stocks and equipment requires the judgement of Solomon and an understanding of the state of the original starting point from which the restored image has come, that virtually no archive technician possesses.
Many technicians acquire experience in judging the quality of a projected film image, and such staff are important in viewing all the work restored for the archive. They should have regular contact with other laboratories and archives - it is quite easy to adopt a local attitude [for example to a preferred contrast or a print density that suits specific projection equipment] and frequent checking with other parts of the film archive world is essential to prevent isolation.
The grader has the best opportunity to judge whether a particular film restoration could be improved by a different film stock, a change in sensitometry or grading, and the print quality-checking technician needs to be in frequent and detailed contact with him.
Most experienced archive film technicians know that a result can always be improved on either by spending more time on testing or by a change in equipment or technique. However economics play an important part in film restoration, and for this reason no original should ever be destroyed, unless the image passes beyond recall, since it may be possible in the future to prepare a far better restoration.
Even today, in 1996, digital film restoration techniques do exist that can restore images to almost whatever image is needed. The cost today is quite unacceptable, but it does illustrate that conventional film restorations are limited in scope and ability and archive images could eventually be restored again at a far higher level of quality
The basic principles
The most effective monitoring of the production procedure in photography is by sampling (in effect what the control strip does of a photographic process). 100% inspection methods as far as individual printed or processed frames are concerned is almost always impossible and often only relevant later in the sequence. Sample information on stages in the procedure can be plotted graphically so that management can be aware of any changes that occur, can avoid operating outside the control limits, and can instigate remedial action when necessary.
Monitoring of the various production stages in photography is always a sampling procedure, and is always devised to provide control decisions. At the end of the final stage of restoration there must come a quality check on the end product and in the case of fairly routine restoration where the image is being preserved because the film base is breaking down but the subject is not of major importance, then it is inevitable that only samples of the product are viewed, or the projection is visual and relatively cursory. 100% checking of the final end product becomes more relevant the more costly or significant, in cinema or historical terms, is the subject matter.
Knowing the production process
An important step in Quality Checking is the knowledge of production process.
The reason is self-evident. If we are Quality Checking a normal production process (i.e. a contemporary production), we can rely on our judgement of current quality standards in film production in our country and/or in our laboratory. Also, we should know if we are checking the results of a major production or of an independent, low-budget film.
But i the case of film restoration and preservation, we really have to go into the details of the process. In facts, how could we judge a print from an original material if we ignore the characteristics the original material had? We could come to the conclusion the print is out of focus, for example, or that the duplication was made at a too high contrast. Maybe this is not the case, most probably all those defects are to be referred to the original materials. But also the contrary is true. We can't and we should not assume that all defects come from the original materials. In facts sometimes these are quite good (e.g. as per an original camera negative). So we must exercise the maximum attention in order to get as much information as possible on the restoration process in order to correctly judge the results. We should know what duplication process was chosen (which printer, what contrast, what film was used, and so on), and we should also see that we can inspect the original materials in order to have a general impression of their photographical and mechanical qualities. Whenever we identify something that we tend to judge as an error in the process, we should go back to the original elements and double check. It is always possible that a very good camera negative suddenly show a deep scratch or spots of decomposition or decolouration. We cannot assume automatically that these "defects" are due to errors in duplication or restoration.
All of this means that Quality Checking in the domain of restoration is a complicated issue, which involves knowledge on different aspects of the process.
