United States Patent [1113572,943 [721 Inventor Ferrand D. E. Corley 2,446,052 7/1948 Loessel et al. .............. .. 356/175 2 Wimbleton Crescent, Islington, Ontario, 2,949,809 8/1960 Canada LandWeisglass ......... et al.., . .. 356/175 [21] Appl. No. 722,867 3,323,431 6/1967 356/175-X 3,380,338 356/175-X Filed Apr. 22, 1968 4/19685/1969 Mitchell ..................... .. [45] Patented Mar. 30, 1971 3,443,868 356/175-X FOREIGN PATENTS 633,539 5/1959 Great Britain ............... .. 356/175 [541 COLOR FILM EVALUATION SYSTEM 459,762 356/175 4 Claims, 5 Drawing Figs. 1,185,396 9/19491/1965 GermanyCanada .............. .................... .. .. 356/175 [52] US. Cl ...................................................... .. 356/175, Primary Examiner-Ronald L. Wibert 35/28.3, 356/191, 356/192, 356/194 Assistant Examiner—Warren A. Sklar [511 Int. Cl ....................................................... ,. GOlj 3/46, Att0rney~George A. Rolston G0 1 j 3/52 [50] Field of Search .......................................... .. 356/ 1 77, 175; 355/(Inquired); 352/(Inquired); 35/28.3, 28.5,53; 356/173, 174, 191-194 ABSTRACT: This speci?cation discloses a system for evaluat References Cited ing the color balance density and contrast of color ?lm by UNITED STATES PATENTS means of projecting the color ?lm onto a screen and visually comparing it with a standard reference image on the screen, 0,553 2/1940 Tarr ........................... .. 356/175-X and to apparatus for such system. F Patented March 30, 1971 3,572,943 FIG. 2 FIG.3 INVENTOR FERRAND D. E. CORLEY BYialemje 14. Fo?fqn PATENT AGENT 3,572,943 l . 2 tCGlLGllt FllLM EVALUATION SYSTEM bility of the production of such a reference image by other means. Thus for example, it is possible that the reference This invention relates to a system for evaluating the color image could be formed by forming strips of a neutral color of a balance of color ?lm, color slides and the like, and more par different density on a transparent support by means of a ticularly to a method and apparatus for evaluating both color vacuum or electrolytic coating with organo~metallic coating balance, and also the density and contrast, of such color ?lms materials. Alternatively, it is possible that such strips can be or color slides, for the purpose of subsequently reprinting the formed and applied directly to the screen upon which the ?lm same making appropriate variations in the color balance from is to be screened, and could be illuminated by suitably masked notations made during such evaluation. white light. Thus, the invention is not limited to any one form The need for accurate color balance of color ?lms now ex of reference image. ists. in the past, ?lms slides and the like were viewed in a dar The foregoing and other advantages will become apparent kened room designated for screening, and under these circum~ from the following description of a preferred embodiment of stances while the color balance of a ?lm or slide might vary considerably, the viewers eye automatically compensated for the invention, which is now given by way of example only with such variation and to the viewers, the color balance would ap reference to the following drawings in which like reference pear natural and lifelike. However, today the introduction of devices refer to like parts thereof throughout the various views color television on which colored slides and colored motion and diagrams and in which: , picture ?lm are viewed in relatively brightly lit rooms has FIG. 1 is a schematic perspective illustration of the system made the accurate color balance of slides and ?lms a much in operation. more critical mater since the human eye under these circum FIG. 2 is an elevational view of a slide carrying the stances will automatically, subconsciously compare the color reference image; image on the television screen with the overall color balance FIG. 3 is an elevational view of a slide carrying a mask of the room or surroundings, and any discrepancy in the color image; balance of the image on the screen will be immediately de FIG. 4 is an elevational view of a ?lter wheel; and, tected. However, notwithstanding this situation, agencies and FIG. 5 is a composite illustration showing the means of ?lm studios still conduct the prescreening and evaluation of mounting the ?lter wheel. ?lms and slides in a darkened screening room. The apparatus required for the operation of the system, ac The present invention therefore provides a system of cording to this preferred embodiment of the invention, is illus evaluating color balance of ?lms, which term is deemed to in trated in FIG. 1, and will be seen to comprise a slide projector clude both motion picture ?lms and slides by screening the 10, a ?lm or slide projector 12, depending upon whether mo same on a screen upon which a standardized reference image tion picture ?lm or color slides are to be evaluated, and a is projected or established by any suitable means, the ?lm screen 14 upon which images from both projectors 10 and 12 being automatically evaluated by the human eye with are projected simultaneously. The slide projector 10 accord reference to such standard image. In many cases, an expert ing to this preferred embodiment is of any suitable type will ?nd that this is all that is required, to enable him to deter~ adapted to accept slides such as those illustrated in FIGS. 2 mine exactly how the color balance of the ?lm should be ad and 3 of any conventional type, and projects the same accu justed, but, the invention also comprehends within the overall rately onto screen 14. The projector 12, if used for motion pic system, the additional step of adjusting the color balance of ture ?lm, should preferably be of the type which can be run the image of the ?lm being screened by predetermined incre 40 both forward and backwards, and should incorporate an ad ments, until the closest match is obtained to the reference justable lens iris (not shown) and should have attached image, such predetermined increment being subsequently thereto a group of ?lter wheels, to be described in more detail reapplied to the adjustment of the image of the film during hereinafter, which may be interposed in any one of many com reprinting. binations into the light beam passing from projector 12 onto In order to achieve this objective it is desirable that the stan 45 screen 14. When operating according to the present invention, dard reference image should comprise a series of ‘panels or the projector 12 is so arranged and positioned and focused strips each of which comprises a precise balancing of that the image therefrom appears in the center rectangular predetermined densities of the three basic colors, the three portion of the screen, such image being designated by the colors together providing a gray appearance of a predeter reference 16. The projector 10 is so arranged and focused that mined density, the densities of the panels varying in predeter the image projected thereby ?lls the rectangular border of the mined increments from very dark to very light gray. A reference image of this type is usually called a “staircase screen surrounding the central image 16. The projector 12 in wedge,” one early form of which was described in an article cludes a conventional assembly of lenses (not shown) in entitled “New CBC. Vidicon Tele-Cine Operating Stan dicated generally as 18 which are combined with a suitable lens iris for adjusting the apertures and thereby varying the in— dards” by S. F. Quinn and J. Bowie Dickson, Journal of the 55 SMPTE. Vol. 73, Dec. 1964, No. 12, pgs. 1009 to 1014. tensity of the projected image. In order to vary the color The image referred to in this article consisted of a slide known balance of the projected image, the four ?lter wheels 20 are as the “Holmes-CBC." slide and in this case, the image was positioned in front of lens 18 on projector 12 so that each such produced on black and white silver-image film. The image ?lter wheel 20 may be rotated separately to bring any one of comprised two groups of 10 separate strips varying in incre the ?ve openings 21 in each wheel 2i) into registration with ments of density, the strips being printed from left to right and lens 18. Each ?lter wheel 20 is provided with ?ve registration from right to left. However, this type of staircase wedge image slots 22 and a central opening 23 for mounting of the same on was suitable only for use in black and white television, and for shaft 27 extending from projector 12. Referring to FIG. 5, use in color television it is considered essential that each of the each of the wheels 20 is provided with a spring washer 25, hav strips in the image transmit a precise balance of red, green and 65 ing a registration key 25a thereon, for interengagement with a blue light at predetermined intensities, usually equal intensi corresponding keyway 27a in shaft 27, and a plurality of ties, and this cannot be achieved generally speaking using a spring tongue members 26, one of which is folded over for in silver image due to the fact that the silver image does not pass terengagement with registration opening 22. A washer 24 is equal amounts of red, green and blue light at varying densities, placed between spring washer 25 and the next adjacent ?lter the denser the silver grains, the more the short wavelengths of wheel 20. At the end of the shaft 27 a retaining nut 2b is pro light will be scattered.