We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
184 LOYD A. JONES AND OTTO SANDVIK [j. s. M. P. K.
desirable in order to compensate for certain contrast losses which occur at different points in the process. For instance, a certain amount of flare may exist in the projection lens, thus spreading a veiling glare over the projected image. In many cases also there is an appreciable amount of stray light incident upon the screen from the general lighting in the theater. These factors all tend to decrease the effective contrast and it seems desirable to make the gamma of the reproduction (7,.), the so-called "over-all gamma," somewhat greater than unity. Since the sound positive must be developed to a gamma of approximately 2.0, it follows that the sound negative should be developed to a gamma of 0.5 or 0.6 in order that the required quality of exposure variations to which the sound negative is subjected can be reproduced in the sound positive as proportional variations in: transmission.
In establishing a laboratory technic for the handling of sound records it is therefore necessary to determine the development conditions which will result in a sound record negative of the desired contrast. The required information can be derived from a sensitometric study of the characteristics of the photographic material. In Fig. 1 are shown the sensitometric curves for motion picture positive film, the material which is used almost exclusively in making the sound record when using the light valve method. These curves show the relationship between density (ordinates) and log exposure (abscissas) for a series of different development times. The exposures from which the data are derived were made in a high intensity sensitometer employing a time scale exposing system, the time factors of exposure varying from 2.5 X 10 ~4 to 0.5 seconds. The light source used in this sensitometer is a high efficiency tungsten lamp with the filament operating at a color temperature of approximately 3100°K. The exposed strips were developed in the standard metol hydroquinone borax formula at 20° C. The resultant densities were read with the emulsion side of the film in contact with an illuminated disk of pot opal glass. The values obtained are therefore those of diffuse density. The times of development used in obtaining the various curves are shown in the first column* of Table I.
In the upper left-hand corner of Fig. 1 are plotted the time (of development) -gamma and the time-fog curves for this material. The time-gamma curve obtained by plotting gamma as a function of development time shows the way in which gamma increases with increasing times of development.