Projection engineering (Sept 1929-Nov 1930)

Page 32 Projection Engineering, September, 1929 Table I Visual character istics of the series of tints No Color Name Hue T Description l No. % 0 Clear base . 100 Hueless, clear 1 Rose Doree 633 1.0 57 Deep warm pink 2 Peachblow 619 4.0 61 Flesh pink 3 Afterglow 603 7.5 66 Orange 4 Firelight 596 12.0 66 Yellow-orange 5 Candleflame 585 17.5 75 Orange-yellow 6 Sunshine 579 23.0 83 Yellow 7 Verdante 520 36.0 57 Green 8 Aquagreen 505 40.0 40 Blue-green 9 Turquoise 490 43.0 46 Blue 10 Azure 484 47.0 28 Sky-blue 11 Nocturne 476 51.0 28 Violet-blue 12 Purplehaze 455 56.5 38 Blue-violet 13 Fleur de lis -575 60.0 25 Blue-purple 14 Amaranth -55 1 64.0 31 Red-purple lb Caprice -537 67.5 53 Cool pink 16 Inferno -50S 71.5 36 Red-magenta 17 Argent 71 Hueless equivalent to a transmission of 100 per cent, density 0. It seemed desirable to express all results in this manner since the factors of interest are those relating to the changes of photoelectric transmission, volume, etc., as compared to the conditions existing when the sound record is carried on a clear film base. Visual Characteristics of the Seventeen Tints In Table I are given data relative to the visual characteristics of these tinted materials. Considerable thought has been given to the names by which ' these tints are to be designated. It seems desirable, from a consideration of the probable associational and emotional value of color when applied to the motion picture screen, to designate these tints by names suggestive of their potential psychological effects and appropriate uses. This particular phase of the subject will be discussed in greater detail in a later section of the paper. In the column designated as "i" under the title "Hue" are given the values of the dominant hue expressed in wavelength. These determinations refer specifically to the color of a white screen when illuminated by light from an arc of the reflector type with the tinted base placed between the light source and the screen. It therefore is a specific designation of the screen color obtained when these materials are used with a light source of this character. It is realized that in practice a certain variation in these hue values will result from the use of light sources differing from the one with which these hue measurements were made. For instance, with a high intensity arc of either the condenser or the reflector type, the color of the emitted light is probably slightly bluer than that emitted by a reflector arc using ordinary hardcored carbons. Under these conditions the hue values will be shifted slightly. The difference, however, is so little as to be considered negligible from the practical standpoint. If these materials are used in a projector employing a high efficiency tungsten lamp there will probably be a rather great departure from the hue values indicated in Table I. This light is much yellower than that emitted by the arc and hence the use of a screen illuminated by a tungsten lamp in conjunction with these tinted bases will give appreciably different hues from those indicated in Table I. In the column designated as "No." under "Hue" are the Ridgway hue numbers. The system of color nomenclature developed by Ridgway 1 is one of the best available. The entire hue gamut, including the spectral hues and the non-spectral purples, is divided in 72 hue steps. These hue steps are equally placed on the sensation scale. 1 Ridcjivay. cloture, 1912. Color Standards and Nomen Tints Evenly Spaced Along Normal Hue Scale In setting up a scale of hue it is not satisfactory to adopt intervals which are identical in wave-length difference because the sensitivity of the eye to hue differences varies enormously throughout the spectrum. In order to establish a normal hue scale in which the steps are equal in terms of ' sensation, it is necessary, therefore, to use wave-length intervals differing widely in magnitude. It will be noted that, with the exception of a region in the orange, yellow, and yellow-green, the hues of these tinted materials are fairly evenly spaced on the normal hue scale. It seems highly desirable to adopt such spacing, since it makes available the entire gamut, of hue and a change from one tint to another produces a hue displacement of known and fairly equivalent subjective magnitude. The positions of the dominant hues of these colors are shown graphically on the chart in Fig. 4. At the left are given the Ridgway hue numbers and the names applied by Ridgway to these hues when occurring in colors of high saturation. At the right in the first column are the Ridgway hue numbers for the tinted positive films, and the names applied to these. It should be remembered that these colors are in general of relatively low saturation and it is considered that these more delicate tints are of greater utility for use in applying color to the motion picture screen than those of higher saturation. It is a rather peculiar coincidence that the colors corresponding to the hue numbers 25 to 35, which are absent from this positive film series, are those which, according to all of the available psychological data (see Luckiesh, loc. cit.), are the colors classified as least agreeable or least preferred. These color preference data are derived from a large group Table II No 0 Photoelectric density characteristics of the Film Tint Potassium D. Clear base 0.0 series Cell Do. 0.0 3.8 3 4 5.4 5.4 4.8 5.4 5 6 5 2 2 0 1.8 1.8 2 0 2.8 2 2 1 8 3 6 1.8 3 5 5.6 1.8 3 8 of tints Caesium D. 0.0 0.15 0.11 0.15 0.11 0 09 0 06 0.18 0 27 0 24 0 27 0 28 0 22 0 30 0 24 0 14 0 22 0.10 0.184 0 30 0 06 0 24 Cell Do. 0 0 1 Rose Doree 0.19 3 0 9 Peachblow 0 . 17 2 2 3 4 Afterglow Firelight Candleflame 0 27 0 27 0 24 3 0 2.2 1 8 6 Sunshine 0 27 1.2 7 Yerdante 0 28 3 6 8 Aquagreen 0 26 5.4 q Turquoise 0.10 4 8 10 Azure 0 09 5 4 11 Nocturne 0 09 5 6 T> Purplehaze 0 10 4 4 13 14 Fleur de lis Amaranth . 0.14 0.11 6 0 4 8 15 16 Inferno 0 09 0 18 2 8 4 4 17 Argent 0 09 2.0 Minimum 0 176 0 28 0 09 3 7 6 0 1 2 Maximum A 0 19 4 S