2900-84-R Memorandum of Project MICHIGAN THE LIMITING TRACE SPACING ON FILM RELATED TO EXPOSURE AND CONTRAST RATIO E. Henry M. Harrison July 1960 RADAR LABORATORY THE UNIVERSITY OF MICHIGAN Ann Arbor, Michigan

Distribution control of Project MICHIGAN Reports has been delegated by the U. S. Army Signal Corps to: Commanding Officer U. S. Army Liaison Group Project MICHIGAN Willow Run Laboratories Ypsilanti, Michigan It is requested that information or inquiry concerning distribution of reports be addressed accordingly. The work reported herein was carried on by Willow Run Laboratories for the U. S. Army Signal Corps under Project MICHIGAN, contract No. DA-36-039 SC-78801, and for Wright Air Development Division under Contract No. AF 33(600)38019. University contract administration is provided to Willow Run Laboratories through The University of Michigan Research Institute.

WILLOW RUN LABORATORIES TEC H N ICAL MEMORAN D UM PREFACE Documents issued in this series of Technical Memorandums are published by Willow Run Laboratories in order to disseminate scientific and engineering information as speedily and as widely as possible. The work reported may be incomplete, but it is considered to be useful, interesting, or suggestive enough to warrant this early publication. Any conclusions are tentative, of course. Also included in this series will be reports of work in progress which will later be combined with other materials to form a more comprehensive contribution in the field. A primary reason for publishing any paper in this series is to invite technical and professional comments and suggestions. All correspondence should be addressed to the Technical Director of Project MICHIGAN. Project MICHIGAN, which engages in research and development for the U. S. Army Combat Surveillance Agency of the U. S. Army Signal Corps, is carried on by Willow Run Laboratories as part of The University of Michigan's service to various government agencies and to industrial organizations. Robert L. Hess Technical Director Project MICHIGAN iii

WILLOW RUN LABORATORIES TEC H N ICAL MEMORANDUM CONTENTS Preface............ iii List of Figures.................... vi Abstract...................... 1 1. Introduction................... 1 2. Description of the Method............. 2 2.1. The Image-Forming Block....... 2 2. 2. Exposure and Processing.......... 3 2.3. Scanning the Image...... 3 2. 4. Discussion of the Test Method......... 3 3. Results....... 4 References.............. 6 Distribution List......... 7 v

WILLOW RUN LABORATORIES TECH N ICAL MEMORANDUM FIGURES 1. Test Block...................... 7 2. Width of Unexposed Portions on Film Reproductions of Grating.. 7 3. Transmission of Light through Variable Grating....... 8 4. Light Transmission through Reference Grating....... 8 5. Test Curves, Ansco Hyscan Ortho Film. 9 6. Test Curves, Ansco Hyscan Film....... 9 7. Test Curves, Ansco Telerecord Film...... 9 8. Test Curves, Du Pont Superior No. 1 Film......... 9 9. Test Curves, Du Pont Superior No. 2 Film......... 10 10. Test Curves, Du Pont Superior No. 3 Film......... 10 11. Test Curves, Du Pont 824-B Film.............10 12. Test Curves, Du Pont 834-B Film.............10 13. Test Curves, Du Pont 931 Film..............11 14. Test Curves, Eastman Kodak Fine Grain Positive.......11 15. Test Curves, Eastman Kodak Lina-Ortho......11 16. Test Curves, Eastman Kodak Microfile..........11 17. Test Curves, Eastman Kodak Panatomic-X......12 18. Test Curves, Eastman Kodak Plus-X........12 19. Test Curves, Eastman Kodak SO 1209....... 12 20. Test Curves, Eastman Kodak Spectrum Analysis No. 1... 12 21. Test Curves, Eastman Kodak Tri-X.......13 22. Test Curves, Eastman Kodak Tri-XAR......13 23. Test Curves, Ilford FP3............ 13 24. Test Curves, Ilford HPS............ 13 25. Resolution vs. Exposure to Maintain a Contrast Ratio of 0. 707. 14 26. Resolution vs. Exposure to Maintain a Contrast Ratio of 0. 500..14 vi

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM THE LIMITING TRACE SPACING ON FILM RELATED TO EXPOSURE AND CONTRAST RATIO ABSTRACT Photographic film is one of the best materials known for storing maximum information in the smallest amount of medium. Data may be inserted in independent channels; it is therefore necessary to know the limiting channel spacing so that the uniqueness of each channel can be preserved. This memorandum describes a procedure to determine the limiting channel spacing. The method consists of contact-printing on a test film the image from a mirror-surfaced, optically flat glass block. In the mirror surface, lines 42 A wide are engraved with a variable spacing from 8. 5 lines /mm to 62. 5 lines/mm. The image is then scanned with a specular densitometer and the light transmission recorded. The scanning aperture is 5 L. From the recording, the contrast ratio at any resolution, i. e., the ratio of contrast at a given resolution to that at a low resolution (8. 5 lines /mm) may be determined. This procedure is carried out with different amounts of exposure, all film being developed under constant conditions. A relationship is then expressed between light transmission through the image and the limiting resolution for a given contrast ratio (e. g., 0. 707). Data for several commercially available films are given. 1 INTRODUCTION Photographic film is one of the best materials known for maximum permanent storage of scientific information in the smallest amount of space. The data may be of several forms, but the maximum storage occurs when the variations of exposure are caused by either alternating cycles or pulses of light. The developed film may be considered as a high-resolution, threedimensional representation in which the exposure corresponds to the third dimension. The data may be inserted as a cathode-ray-tube trace in channels which may be of considerable width or only as wide as the limiting spacing so that the data, when recovered from storage by a flying-spot scanner, for example, have deteriorated by only a designated amount. The deterioration is a loss in contrast caused by the overlap of adjacent traces. This degradation is only a portion of the total degradation, the total being the sum of that caused by each 1

WILLOW RUN LABORATORIES TECH N ICAL MEMORANDUM component in the display system. This memorandum discusses the limiting film spacing as a function of contrast and describes a simple method for the experimental determination of this relationship. From this information the minimum channel spacing may be defined and a given contrast ratio maintained. This experimental method is also suitable for surveys of other photographic parameters. 2 DESCRIPTION OF THE METHOD The experimental method consists of contact printing on the film under study the image from an optically flat glass block which has been mirror-coated and engraved. The film is then developed under controlled conditions. The resulting film image is then scanned with a specular densitometer, and the resulting light transmission is recorded with a Sanborn recorder. The recording shows the exposure, the total contrast, the film-base density, and the contrast at any particular resolution spacing. This method of testing is applicable for survey studies where there are any number of variables, such as exposure and film-development parameters. In this work only the film exposures were varied. 2.1. THE IMAGE-FORMING BLOCK The image-forming block is shown in Figure 1. The image formed by exposure through the block is also shown. Because the block was originally procured for a different purpose, the image follows a curve instead of a straight line. The block is constructed of quality glass that has been ground optically flat and mirrorcoated. In the mirror coat, a grating has been engraved in which the lines are 42 i (23. 8 lines/mm) wide with varying spacing between lines. Along the center of the grating (vertical straight portion) the widest distance between the lines is 118. 2 M (8. 5 lines/mm), and the narrowest distance is 15. 9 [ (62. 8 lines/mm). The spacing between the lines and the corresponding lines per millimeter are shown in Figure 2. The light transmission of this grating alone was measured on the densitometer using a very fine photomultiplier aperture (0. 005 inch). This aperture corresponds approximately to a 5-si aperture in the plane of the grating. It was found that the maximum transmission was uniform over the entire grating (85% + 2% of the incident light). 2

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 2.2. EXPOSURE AND PROCESSING The film was positioned on a baseboard of a photographic enlarger and the block firmly pressed down on it with the grating toward the film. The enlarger lens iris was set at f/22, and the film was exposed for 0. 2, 0. 4, 0. 6, and 0. 8 second, one image at each exposure. Exposures were made using a Wratten 47 filter (blue light corresponding to P-11 phosphor) and a 5461-X filter (green light). Neutral density filters were added in the light head of the enlarger to reduce the exposure intensity on the photographically faster films. The films were then developed in a Houston-Feerless developing machine, in DK 76 developer at 69~F and at a machine speed of 6 fpm. 2.3. SCANNING THE IMAGE The images were then scanned with the densitometer, using the 0. 005-inch aperture previously mentioned, and the light transmissions recorded with a Sanborn recorder. Care was taken that the scanning speed did not cause electrical frequencies that exceeded the capabilities of the instruments used, and the densitometer linearity was checked against neutral-density filters. Sample recordings are shown in Figure 3. From these recordings, as previously mentioned, the parameter data can be determined. 2.4. DISCUSSION OF THE TEST METHOD Before presenting and discussing test results, it may be well to discuss certain aspects of the test. For years, optical resolution has been used to determine design criteria. Tests have been conducted with an alternating black-and-white line chart as a test target; as long as one black line is discernible from the next adjacent black line, the two are said to be resolved. It has been estimated (Reference 1) that the resulting contrast is approximately 2 to 3% of the original contrast in the line chart; 98% of the original contrast has been lost. Even if the lines are resolved, where the contrast is equivalent to the third dimension of data storage such a large loss can hardly be tolerated. Recent optical theory is becoming patterned after electrical communication theory; the spatial frequency responses of film, lenses, and combinations of both have been determined from optical sine-wave patterns. A knife-edge exposure has also been used to obtain the spatial frequency response which is the Fourier transform (Reference 2) of the derivative (line-spread function) (Reference 3) of the edge function associated with such an exposure. 3

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM Besides frequency response, another widely used term in evaluating photographic results is "acutance. " This is defined (Reference 4) as the mean-square gradient of the edge function divided by the density differences between two arbitrary points on the edge-function curve. The method reported in this memorandum produces in each master exposure a series of identical knife-edge line exposures placed at varying distances from each other. Each line exposure, except for unavoidable light diffraction at the edges, is a true knife-edge exposure because no lenses are used. Any particular line exposure may be minutely examined to determine the edge function, acutance, and spatial frequency response. In addition, this method is designed to find the spacing at which the edge functions of successive line exposures overlap by only a specified amount. This specification may be labeled "contrast ratio, " which is the ratio of two contrasts, one at a spacing where the edge functions do overlap and the other at a spacing where the edge functions do not overlap. The experimental determination of the contrast ratio is achieved by scanning the successive line exposures in each master exposure. At wide spacing, the amount of light recorded will vary from that transmitted through the base of the film to that transmitted through the exposed portions. As the line spacing decreases, the film in the spaces will be increasingly exposed because of edge overlap, and the resulting light transmission will decrease. The light transmitted through the intentionally exposed portions will decrease slightly, but will be substantially the same. Therefore the image will indicate the loss in contrast, and will indicate the maximum exposure that may be associated with a desired contrast ratio and spacing. 3 RESULTS Samples of the following films were studied. Ansco Du Pont Eastman Kodak Ilford Hyscan Ortho Superior No. 1 Fine Grain Positive FP3 Hyscan Superior No. 2 Lina-Ortho HPS Telerecord Superior No. 3 Microfile 824-B Panatomic-X 834-B Plus-X 931 SO 1209 Spectum Analysis No. 1 Tri-X Tri-XAR 4

WILLOW RUN LABORATORIES TECH N ICAL MEMORANDUM A reconstruction of the Sanborn recording for Tri-X film when exposed to blue light (Wratten 47 filter) is shown in Figure 4. The ordinate is expressed as the fraction of incident light transmitted through the film, and the abscissa is the spacing between exposures. The four decending curves denote the transmission through the unexposed portions of the film at the four different exposures. The four bottom curves denote the transmission through the exposed portions of the film. From this figure, the spacing can be determined at which a desired contrast ratio can be achieved; the contrast at a spacing of 8. 5 lines/mm is considered unity. Figures 5 through 24 show the relationship between the specular density of the developed film and the spacing between line exposures while a contrast ratio of 0. 707 and 0. 500 is maintained. On the graphs, the dots indicate the 47 filter and the stars indicate the 5461 filter. The test curves show that, in the main, the results from the different films are quite similar. The results from some of the photographically slower, higher-resolving films are more favorable than the results from the photographically faster films; that is, a higher density signal can be more closely recorded on the slower film. The method reported is not intended primarily to determine the film's frequency-response curve; however, the curve can be determined from the edge-function spread-function frequencyresponse relationships previously mentioned. That this relationship exists is borne out by the similarity between Figure 4 and the published frequency-response curves (Reference 5). These published curves of different photographic films, with the exception of those that are very slow photographically, show that the frequency responses for contrast ratios of 0. 7 and 0. 5 are very nearly the same, and that the large increase in resolving power is attained at low contrast ratios where, for the recording techniques mentioned in this memorandum, the increase is of no avail. In Figures 25 (contrast ratio of 0. 707) and 26 (contrast ratio of 0. 5), the test data from Eastman Kodak Microfile, Panatomic-X, and Tri-X film have been shown, along with a design curve which is shown dotted. The one design curve is drawn because of the similarity of test results. The selection of an individual film to be used in a specific instrument depends on available light and lenses, and the amount of granular noise that can be tolerated. It should be emphasized that results from very high-resolving, extremely slow film, such as Eastman Kodak 649GH film, will not follow this design curve. Recent comment on this work has been concerned with re-reflection of light reflected from film emulsion grains inasmuch as the test image is engraved in a mirrored surface. 5

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM Future work will be carried on with a test object in which lines have been engraved in a lowreflectance surface; however, it is felt that, because of the similarity of these results with other published results, the inaccuracies caused by the mirror surface are small. REFERENCES 1. O. Schade, "Image Gradation, Graininess and Sharpness in Television and Motion Picture Systems, " Part II, J. Soc. Motion Picture Television Engrs. March 1952, Vol. 58, p. 181. 2. R. L. Lamberts, "Relationship between the Sine-Wave Response and the Distribution of Energy in the Optical Image of a Line, " J. Opt. Soc. Am., July 1958, Vol. 48, p. 490. 3. R. L. Lamberts, G. C. Higgins, and R. N. Wolfe, "Measurement and Analysis of the Distribution of Energy in Optical Images," J. Opt. Soc. Am., July 1958, Vol. 48, p. 487. 4. G. C. Higgins and F. H. Perrin, "The Evaluation of Optical Images," Phot. Sci. Eng., August 1958, Vol. 2, p. 66. 5. R. L. Lamberts, "Measurement of Sine-Wave Response of a Photographic Emulsion," J. Opt. Soc. Am., May 1959, Vol. 49, p. 425. 6

W I L OW R U N L AB O R A TO R I E S T E C Ht N I C A L M E M O R A ND UM FIGUfEl 1. TEST IL O0..,.,K 0 01 1 fit......,,,.... n 0.0-................ F.:: 1: 5:0.......................................................................................................................... thM t t l t.,5 o /1...........................................,..,. r.,. F It! 2. T.... OF'.... S F FIGURiEi 2. WI'TH OF UNEXPOSEI' PORt'TIONS ON FILM:'EPRODUC"IO'S"* OF GAI 7.)..................................................................................................O..G...A.

WILLOW RUN LABORATORIES TECH N ICAL MEMORANDUM EASTMAN MICROFILE FILM' {; i - - -.-' L +; - I I.._..i,:',;, i'\..,. J I, I. I., _,,,.......:., -:......&..i. L i LIPH' I....'o ----- ui. i ln U. li ill~iHidiiUi;iiti,(n lj.iiiiJ:..:.,i it'i'='"'..... "' ""......."'.;. i. i t.. |. |.:.:. _..!,..1,_ _I.....,PI,.I _.,., h -' - - -. j,.1! 1 1 1.. i'.'"'..... - l-"' - r l!'!"',,.r"' i" L n' r';.7,-!! 7:'i -,'" F' r! -. r i'-!! T"' -'',- I 1 v -1TM BY HORIZONTAL LINES I70 ---— TRI-X Film I. =:'':, I j: __ __ Wratten 47 Filter 3-0.0.6 Sec. Exposure %:,,.v ^_ 4-0.8 Sec. Exposure -' _'_' __ I I I ___'^-.:.' "''''....... "''1 "',. I........rr - - J. -I I'I 0.8 i I Ii1 r11M Iri d'm~ 0% & 100% TR ANSMISSION SHOW FIGURE. LIGHT TRANSMISSION OF LIGHT THROUGH VARIABLEFERENCE GRATING Wratten 47 Filter 8 1- 0.2 Sec. Exposure 0,50 4.,\ 3 - 0.6 Sec. Exposure 1.m = <g - 0.8 Sec. Exposure BY 1ORIZONTAL LINES FIGURE 4. LIGHT TRANSMISSION OF LIGHT THROUGH VAREFERENCIABLE GRATING FIGRE4. IGT RANMISIN TROGH EFRECE RAI8

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 70- 70 \0.500 60- 60- 0.707 50 0.5001 50. 0.707 0.5\~.500 4;~~~~~0 o 0.500 140 - 40 0.707'! 030- 30 * fe20 to 20 10 10 * ~ 0 0.4 0.8 1.2 1.6 2.0 0 0.4 0.8 1.2 1.6 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 5. TEST CURVES, ANSCO FIGURE 6. TEST CURVES, ANSCO HYSCAN ORTHO FILM HYSCAN FILM 70- 70 60 -60 0.500 0.707 3E 0 0.707 30 ~20- \ ~20- _ 10- 10- 0 0.4 0.8 1.2 1.6 2.0 0 0.4 0.8 1.2 1.6 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 7. TEST CURVES, ANSCO FIGURE 8. TEST CURVES, DU PONT TELERECORD FILM SUPERIOR NO. 1 FILM 9 O~SE~~LA ESIYSEUA EST FIGURE~~~~~~~~ 20-S UVSASOFGRE8 ETCRVS UP O~TEER 0~DFL SPRO N.~F

WILLOW RUN LABORATO R I ES TECHNICAL MEMORANDUM 70 70 0.500 60 600.707 \ 50 \ 50- \0.500 ) 40- 40 0.707 z 0.500 \0 o \ <20- 20 0.707 10 10I!! I I I I i' I I I I I I I I I I I 0 0.4 0.8 1.2 1.6 2.0 0 0.4 0.8 1.2 1.6 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 9. TEST CURVES, DU PONT FIGURE 10. TEST CURVES, DU PONT SUPERIOR NO. 2 FILM SUPERIOR NO. 3 FILM 70 70 60 60- 0.707 50 E 50 0.500 0.500 40 - 40 — t 0 0.707 0.707 0 30 - 30 Z Z 10- 10- I I I I II 0 0.4 0.8 1.2 1.6 2.0 0 0.4 0.8 1.2 1.6 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 11. TEST CURVES, DU PONT FIGURE 12. TEST CURVES, DU PONT 824-B FILM 834-B FILM 10

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 70- 70 0.500 0.500 60- 60 0.707 \ S 50- 50 EAQ~ \\ttt t ~ T 0.707 40 U 40 O30 O 30 < 20 20 10- 10 0 0.4 0.8 1.2 1.6 2.0 0 0.4 0.8 1.2 1.6 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 13. TEST CURVES, DU PONT FIGURE 14. TEST CURVES, EASTMAN 931 FILM KODAK FINE GRAIN POSITIVE 70- 700.500 60 0.500 60 0.707 0.707 50 \ 50 5461A Z 30o- 30 - - ~0 i<^ 20- 2010- 100 0.4 0.8 1.2 1.6 20 0 0.4 0.8 1.2 16 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 15. TEST CURVES, EASTMAN FIGURE 16. TEST CURVES, EASTMAN KODAK LINA-ORTHO KODAK MICROFILE 11

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 70- 70 5461 0.500 60 — 60- 7 s0.500 0.707 0 50- 50- - * 0 0.707 g 40- 40 10- 10- 0 0.4 0.8 1.2 1.6 2.0 0 0.4 0.8 1.2 1.6.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 17. TEST CURVES, EASTMAN FIGURE 18. TEST CURVES, EASTMAN KODAK PANATOMIC-X KODAK PLUS-X 50 50 — Q 0.70707 0.707 ^ ^^ ^\0.500 30 0.7030 0 20 < 20 0.707dr 30- 30- 0 0.4 0.8 1.2 1.6 2.0 0 0.4 0.8 1.2 1.6 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 19. TEST CURVES, EASTMAN FIGURE 20. TEST CURVES, EASTMAN KODAK SO 1209 KODAK SPECTRUM ANALYSIS NO. 1 12

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 70 700.500 5461 A 60 5461 A 60 —.-~_ ___._^^ ^^ - 0.707 50 0. 50 0.500 40 0.707 40 0.00 0.707 0 30 30Z Z 20 p 20 10 10- I I I I *I I I I I 0 0.4 0.8 1.2 1.6 2.0 0.4 0.8 1.2 1.6 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 21. TEST CURVES, EASTMAN FIGURE 22. TEST CURVES, EASTMAN KODAK TRI-X KODAK TRI-XAR 70- 70 0.707 60- \60 \0.500 N 500 2 50 X 40- \ 40 — ~a \^~.0.500 0 30O - 30 Z ~ 0.707 CI) 20 ~ 20- -- 10- 10. *I I I* *I *:I.,..I.. I.II I I I I I I I I 0 0.4 0.8 1.2 1.6 2.0 0 0.4 0.8 1.2 1.6 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 23. TEST CURVES ILFORD FIGURE 24. TEST CURVES, ILFORD FP3 HPS 13

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM 70 70 Microfile 47 and Pan-X 5461 Microfile 47 and Pan-X 5461 60- \60 \Microfile (5461) Microfile (5461) | 50 \g 50- Design Curves Design Curve1 Tri-X 40. \ 40 3030 30Z Pan-X 47 T Pan-X47 i-X 20 20 10 10 0 0.4 0.8 1.2 1.6 2.0 0 0.4 0.8 1.2.6 2.0 SPECULAR DENSITY SPECULAR DENSITY FIGURE 25. RESOLUTION VS. EXPO- FIGURE 26. RESOLUTION VS. EXPOSURE TO MAINTAIN A CONTRAST RATIO SURE TO MAINTAIN A CONTRAST RATIO OF 0. 707 OF 0. 500 14

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM DISTRIBUTION LIST 3, PROJECT MICHIGAN REPORTS 1 July 1960-Effective Date Copy No. Addressee Copy No. Addressee 1 Office, Chief of Research & Development 46 Director, U. S. Army Engineer Department of the Army, Washington 25, D. C. Research & Development Laboratories ATTN: Chief, Communications-Electronics Division Fort Belvoir, Virginia ATTN: Chief, Topographic Engineer Department 2 Office, Chief of Research & Development Department of the Army, Washington 25, D. C. 47 Director, U. S. Army Engineer ATTN: Army Research Office Research & Development Laboratories Fort Belvoir, Virginia 3 Office, Assistant Chief of Staff for Intelligence ATTN: Chief, Electrical Engineering Department Department of the Army, Washington 25, D. C. ATTN: Chief, CombatDevelopment/G-2 Air Branch 48-50 Director, U. S. Army Engineer Research & Development Laboratories 4 CommandingGeneral, U. S. Continental Army Command Fort Belvoir, Virginia Fort Monroe, Virginia ~~~~Fort Monroe, Virginia ~ATTN: Technical Documents Center ATTN: ATSWD-G 51 Commandant, U. S. Army Command & General 5-6 Commanding General, U. S. Army Combat Staff College Surveillance Agency 1Su~rv~eil~l~~a~n~e Agency~,Fort Leavenworth, Kansas 1124 N. Highland Street, Arlington 1, Virginia ATTN: Archives 7-8 Chief, Research & Development Division Office of the Chief Signal Officer 52 Commandant, U. S. ArmyArmor School Department of the Army, Washington 25, D. C. Fort Knox, Kentucky ATTN: Combat Developments Group 9-35 Commanding Officer, U. S. Army Signal Research & Development Laboratory 53-54 Assistant Commandant, U. S. Army Artillery & Fort Monmouth, New Jersey Missile School ATTN: SIGFM/EL-DR Fort Sill, Oklahoma 36 Commanding General, U. S. Army Electronic 55-57 Assistant Commandant, U. S. Army Air Defense School Proving Ground Fort Bliss, Texas Proving Ground Fort Huachuca, Arizona 58 Commandant, U. S. Army Air Defense School ATTN: Technical Library Fort Belvoir, Virginia ATTN: Combat Development Group 37 Office of the Director, Defense Research& Engineering ATTN: ombat Develoment Gro Technical Library Technical Library 59 Commandant U. S. Army Signal School Department of Defense, Washington 25, D. C. Fort Monmouth, New Jersey 38 Director, Weapons Systems Evaluation Group ATTN: SIGFM/SC-DO Room 1E880, The Pentagon, Washington 25, D. C. 60 Commandant, U. S. Army Aviation School 39 Chief of Engineers Fort Rucker, Alabama Department of the Army, Washington 25, D. C. 61-62 President, U. S. Army Artillery Board ATTN: Research & Development Division Fort Sill, Oklahoma Fort Sill, Oklahoma 40 Office, Chief of Ordnance Research& Development 63 President, U. S. Army Aviation Board Division President, U. S. Army Aviation Board Division ~~~~~~~~~~~Division ~Fort Rucker, Alabama Department of the Army, Washington 25, D. C. ATTN: ORDTB, Research & Special Projects 64 President, U. S. Army Air Defense Board Fort Bliss, Texas 41 Commanding Officer, Army Map Service Corps of Engineers 65 President, U. S. Army, Airborne & Electronics Board U. S. Army, Washington 25, D. C. Fort Bragg, North Carolina ATTN: Document Library 66-67 President, ArmyIntelligence Board, U. S. Army 42-43 Chief, U. S. Army Security Agency Intelligence Center Arlington Hall Station, Arlington 12, Virginia Fort Holabird, Maryland 44-45 Commander, Army Rocket & Guided Missile Agency 68 Office of Naval Operations Redstone Arsenal, Alabama Department of the Navy, Washington 25, D. C. ATTN: Technical Library, ORDXR-OTL ATTN: OP-07T 15

WILLOW RUN LABORATORIES TECHNICAL MEMORANDUM DISTRIBUTION LIST 3 1 July 1960-Effective Date Copy No. Addressee Copy No. Addressee 69-72 Office of Naval Research, Department of the Navy 91-98 Commander, Wright Air Development Division 17th & Constitution Ave., N. W., Washington 25, D. C. Wright-Patterson Air Force Base, Ohio ATTN: Code 463 ATTN: WCLROR 73-74 Director, U. S. Naval Research Laboratory 99-108 ASTIA (TIPCR) Washington 25, D. C. Arlington Hall Station, Arlington 12, Virginia ATTN: Code 2027 109 Commander, Rome Air Development Center Griffiss Air Force Base, New York 75 Commanding Officer, U. S. Navy Ordnance Laboratory ATTN: RCVSL-1 Corona, California ~~ATTN-~:~ Library n110 Commander, Rome Air Development Center Griffiss Air Force Base, New York 76 Commanding Officer & Director, U. S. Navy ATTN: RCWIR Electronics Laboratory San Diego 52, California 111-112 Commandant of the Marine Corps,Headquarters U. S. Marine Corps, Washington 25, D. C. ATTN: Library ATTN: Code A02 77 Department of the Air Force,Headquarters, USAF 113 Commandant of the Marine Corps,Headquarters 113 Commandant of the Marine Corps, Headquarters Washington 25, D. C. U. S. Marine Corps, Washington 25, D. C. ATTN: AFOIN-1B1 ~~~~~ATTN: AFOIN-l~B1 ~ATTN: Code A04E 78 Department of the Air Force,Headquarters, USAF 114-117 Central Intelligence Agency Washington 25, D. C. 2430 E. Street, N. W., Washington 25, D. C. ATTN: AFOAC-E/A ATTN: OCR Mail Room 79 Department of the Air Force, Headquarters, USAF 118-122 National Aeronautics & Space Administration Washington 25, D. C. 1520 H. Street, Northwest, Washington 25, D. C. ATTN: AFDRD 123-124 Combat Surveillance Project 80 Department of the Air Force, Headquarters, USAF Cornell Aeronautical Laboratory, Incorporated Washington 25, D. C. Box 168, Arlington 10, Virginia ATTN: Directorate of Requirements ATTN: Technical Library 125 The RAND Corporation 81 Department of the Air Force,Headquarters, USAF 1700 Main Street, Santa Monica, California Washington 25, D. C. ATTN: Library ATTN: AFCIN-3B3b 126 Chief Scientist, Research & Development Division 82 Commander in Chief,Headquarters, Strategic Office of the Chief Signal Officer Air Command Office of the Chief Signal Officer Air Command Department of the Army, Washington 25, D. C. Offutt Air Force Base, Nebraska ~~~~ATTN-~:~ DINC ~127 Stanford Research Institute, Document Center Menlo Park, California 83-84 Commander in Chief,Headquarters, Strategic ATTN: Acquisitions Air Command Offutt Air Force Base, Nebraska 128 Operations Research Office Offutt Air Force Base, Nebraska The Johns Hopkins University The Johns Hopkins University ATTN: DORQP 6935 Arlington Road, Bethesda, Maryland Washington 14, D. C. 85 Headquarters, Tactical Air Command Langley Air Force Base, Virginia ATTN: Chief Intelligence Division ATTN: TOOA 129 Columbia University, Electronics Research Laboratories 632 W. 125thStreet, New York 27, New York 86-88 Headquarters, Tactical Air Command Langley Air Force Base, Virginia.~ ~~~~~~~ATTN:~ TORQ VIA: Commander, Rome Air Development Center Griffiss Air Force Base, New York 89 Commander, Air Technical Intelligence Center ATTN: RCSSTL-1 Wright-Patterson Air Force Base, Ohio ~ATTN:~ AFTTM~CIN-4B/a ~130-131 Cornell Aeronautical Laboratory, Incorporated 4455 Genesee Street, Buffalo 21, New York 90 Commander, Wright Air Development Division ATTN: Librarian Wright-Patterson Air Force Base, Ohio Wright-Patterson Air Force Base, Ohio VIA: Bureau of Aeronautics Representative ATTN: WCOSI-Library 4455 Genesee Street, Buffalo 21, New York 16

WILLOW RUN LABORATORIES TECH N ICAL MEMORANDUM DISTRIBUTION LIST 3 1 July 1960-Effective Date Copy No. Addressee Copy No. Addressee 132 Control Systems Laboratory 136 Visibility Laboratory, Scripps Institution of University of Illinois, Urbana, Illinois Oceanography.~~~~~~~~~ATTN: Librarian.University of California, San Diego 52, California ATTN: Librarian VIA: ONR Resident Representative 1209 W. Illinois Street, Urbana, Illinois 137 U. S. Continental Army Command Liaison Officer, Project MICHIGAN 133-134 Director, Human Resources Research Office Liaison Officer Proje MICHIGAN The George Washington University Willow Run Laboratories, Ypsilanti, Michigan P. 0. Box 3596, Washington 7, D. C. ATTN: Library 138 Commanding Officer, U. S. Army Liaison Group 135 The U. S. Army Aviation HRU Project MICHIGAN P. 0. Box 428, Fort Rucker, Alabama Willow Run Laboratories, Ypsilanti, Michigan 17

AD Div. 24/2 UNCLASSIFIED AD Div. 24/2 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Photographic film-Test Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Photographic film-Test THE LIMITING TRACE SPACING ON FILM RELATED TO results THE LIMITING TRACE SPACING ON FILM RELATED TO results EXPOSURE AND CONTRAST RATIO by E. Henry and M. Harrison. I. Title: Project MICHIGAN EXPOSURE AND CONTRAST RATIO by E. Henry and M. Harrison. I. Title: Project MICHIGAN Memorandum of Project MICHIGAN. July 60. 14 p. incl. illus., II. Henry, E., and Harrison, M. Memorandum of Project MICHIGAN. July 60. 14 p. incl. illus., II. Henry, E., and Harrison, M. 5 refs. III. U. S. Army Signal Corps 5 refs. III. U. S. Army Signal Corps (Memo. no. 2900-84-R) IV. Contract DA-36-039 (Memo. no. 2900-84-R) IV. Contract DA-36-039 (Contract DA-36-039 SC-78801) Unclassified report SC-78801 (Contract DA-36-039 SC-78801) Unclassified report SC-78801 Photographic film is one of the best materials known for storing Photographic film is one of the best materials known for storing maximum information in the smallest amount of medium. Data maximum information in the smallest amount of medium. Data may be inserted in independent channels; it is therefore necessary may be inserted in independent channels; it is therefore necessary to know the limiting channel spacing so that the uniqueness of each to know the limiting channel spacing so that the uniqueness of each channel can be preserved. channel can be preserved. This memorandum describes a procedure to determine the limiting This memorandum describes a procedure to determine the limiting channel spacing. The method consists of contact-printing on a test channel spacing. The method consists of contact-printing on a test film the image from a mirror-surfaced, optically flat glass block. film the image from a mirror-surfaced, optically flat glass block. In the mirror surface, lines 42 i wide are engraved with a variable In the mirror surface, lines 42 p. wide are engraved with a variable spacing from 8. 5 lines/mm to 62. 5 lines/mm. The image is then Armed Services spacing from 8. 5 lines/mm to 62. 5 lines/mm. The image is then Armed Services scanned with a specular densitometer and the light transmission Technical Information Agency scanned with a specular densitometer and the light transmission Technical Information Agency recorded. The scanning aperture is 5 i. UNCLASSIFIED recorded. The scanning aperture is 5 A. UNCLASSIFIED (over) (over) AD Div. 24/2 UNCLASSIFIED AD Div. 24/2 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Photographic film-Test Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Photographic film-Test THE LIMITING TRACE SPACING ON FILM RELATED TO results THE LIMITING TRACE SPACING ON FILM RELATED TO results EXPOSURE AND CONTRAST RATIO by E. Henry and M. Harrison. I. Title: Project MICHIGAN EXPOSURE AND CONTRAST RATIO by E. Henry and M. Harrison. I. Title: Project MICHIGAN Memorandum of Project MICHIGAN. July 60. 14 p. incl. illus., II. Henry, E., and Harrison, M. Memorandum of Project MICHIGAN. July 60. 14 p. incl. illus., II. Henry, E., and Harrison, M 5 refs. III. U. S. Army Signal Corps 5 refs. In. U. S. Army Signal Corps (Memo. no. 2900-84-R) IV. Contract DA-36-039 (Memo. no. 2900-84-R) IV. Contract DA-36-039 (Contract DA-36-039 SC-78801) Unclassified report SC-78801 (Contract DA-36-039 SC-78801) Unclassified report SC-78801 Photographic film is one of the best materials known for storing Photographic film is one of the best materials known for storing maximum information in the smallest amount of medium. Data maximum information in the smallest amount of medium. Data may be inserted in independent channels; it is therefore necessary may be inserted in independent channels; it is therefore necessary to know the limiting channel spacing so that the uniqueness of each to know the limiting channel spacing so that the uniqurness of each channel can be preserved. channel can be preserved. This memorandum describes a procedure to determine the limiting This memorandum describes a procedure to determine the limiting channel spacing. The method consists of contact-printing on a test channel spacing. The method consists of contact-printing on a test film the image from a mirror-surfaced, optically flat glass block. film the image from a mirror-surfaced, optically flat glass block. In the mirror surface, lines 42 ji wide are engraved with a variable In the mirror surface, lines 42 ti wide are engraved with a variable spacing from 8. 5 lines/mm to 62. 5 lines/mm. The image is then Armed Services spacing from 8. 5 lines/mm to 62. 5 lines/mm. The image is then Armed Services scanned with a specular densitometer and the light transmission Technical Information Agency scanned with a specular densitometer and the light transmission Technical Information Agency recorded. The scanning aperture is 5 A. UNCLASSIFIED recorded. The scanning aperture is 5 Ii. UNCLASSIFIED (over) (over)

AD UNCLASSIFIED AD UNCLASSIFIED From the recording, the contrast ratio at any resolution, i. e., UNITERMS From the recording, the contrast ratio at any resolution, i. e., UNITEMS the ratio of contrast at a given resolution to that at a low resolution the ratio of contrast at a given resolution to that at a low resolution Photography (8.5 lines/mm) may be determined. This procedure is carried Photograpy(8 5 lines/mm) may be determined. This procedure is carried Fil out with different amounts of exposure, all film being developed Channel out with different amounts of exposure, all film being developed Channel under constant conditions. A relationship is then expressed be- under constant conditions. A relationship is then expressed be- Spacing tween light transmission through the image and the limiting res- Spacing tween light transmission through the image and the limiting res- Densitnmetr olution for a contrast ratio (e. g., 0. 707). Data for several Densitometer olution for a contrast ratio (e. g., 0. 707). Data for severaltransmiso commercially available films are given. Light transmission commercially available films are given. Light transmission UNCLASSIFIED UNCLASSIFIED AD UNCLASSIFIED AD UNCLASSIFIED From the recording, the contrast ratio at any resolution, i. e., UNITERMS From the recording, the contrast ratio at any resolution, i. e., UNITERMS the ratio of contrast at a given resolution to that at a low resolution the ratio of contrast at a given resolution to that at a low resolution Photography (8.5 lines/mm) may be determined. This procedure is carried Pogp hy(8. 5 lines/mm) may be determined. This procedure is carried F Pl out with different amounts of exposure, all film being developed Channel out with different amounts of exposure, all film being developed Channel under constant conditions. A relationship is then expressed be- ang under constant conditions. A relationship is then expressed be- Spacing tween light transmission through the image and the limiting res- Spacingstween light transmission through the image and the limiting res- Densitomete olution for a contrast ratio (e. g., 0. 707). Data for several Densitometerrolution for a contrast ratio (e. g., 0. 707). Data for several L t commercially available films are given. Lght tasiioncommercially available films are given.Light transmission UNCLASSIFIED UNCLASSIFIED

AD Div. 24/2 UNCLASSIFIED AD Div. 24/2 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Photographic film-Test Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Photographic film-Test THE LIMITING TRACE SPACING ON FILM RELATED TO results THE LIMITING TRACE SPACING ON FILM RELATED TO results EXPOSURE AND CONTRAST RATIO by E. Henry and M. Harrison. I. Title: Project MICHIGAN EXPOSURE AND CONTRAST RATIO by E. Henry and M. Harrison. I. Title: Project MICHIGAN Memorandum of Project MICHIGAN. July 60. 14 p. incl. illus., II. Henry, E., and Harrison, M. Memorandum of Project MICHIGAN. July 60. 14 p. incl. illus., II. Henry, E., and Harrison, M. 5 refs. III. U. S. Army Signal Corps 5 refs. III. U. S. Army Signal Corps (Memo. no. 2900-84-R) IV. Contract DA-36-039 (Memo. no. 2900-84-R) IV. Contract DA-36-039 (Contract DA-36-039 SC-78801) Unclassified report SC-78801 (Contract DA-36-039 SC-78801) Unclassified report SC-78801 Photographic film is one of the best materials known for storing Photographic film is one of the best materials known for storing maximum information in the smallest amount of medium. Data maximum information in the smallest amount of medium. Data may be inserted in independent channels; it is therefore necessary may be inserted in independent channels; it is therefore necessary to know the limiting channel spacing so that the uniqueness of each to know the limiting channel spacing so that the uniqueness of each channel can be preserved. channel can be preserved. This memorandum describes a procedure to determine the limiting This memorandum describes a procedure to determine the limiting channel spacing. The method consists of contact-printing on a test channel spacing. The method consists of contact-printing on a test film the image from a mirror-surfaced, optically flat glass block. film the image from a mirror-surfaced, optically flat glass block. In the mirror surface, lines 42 ji wide are engraved with a variable In the mirror surface, lines 42 1 wide are engraved with a variable spacing from 8. 5 lines/mm to 62. 5 lines/mm. The image is then Armed Services spacing from 8. 5 lines/mm to 62. 5 lines/mm. The image is then Armed Services scanned with a specular densitometer and the light transmission Technical Information Agency scanned with a specular densitometer and the light transmission Technical Information Agency recorded. The scanning aperture is 5i. UNCLASSIFIED recorded. The scanning aperture is 5 pi. UNCLASSIFIED (over) (over) AD Div. 24/2 UNCLASSIFIED AD Div. 24/2 UNCLASSIFIED Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Photographic film-Test Willow Run Laboratories, U. of Michigan, Ann Arbor 1. Photographic film-Test THE LIMITING TRACE SPACING ON FILM RELATED TO results THE LIMITING TRACE SPACING ON FILM RELATED TO results EXPOSURE AND CONTRAST RATIO by E. Henry and M. Harrison. I. Title: Project MICHIGAN EXPOSURE AND CONTRAST RATIO by E. Henry and M. Harrison. I. Title: Project MICHIGAN Memorandum of Project MICHIGAN. July 60. 14 p. incl. illus., II. Henry, E., and Harrison, M. Memorandum of Project MICHIGAN. July 60. 14 p. incl. illus., II. Henry, E., and Harrison, M. 5 refs. In. U. S. Army Signal Corps 5 refs. In. U. S. Army Signal Corps (Memo. no. 2900-84-R) IV. Contract DA-36-039 (Memo. no. 2900-84-R) IV. Contract DA-36-039 (Contract DA-36-039 SC-78801) Unclassified report SC-78801 (Contract DA-36-039 SC-78801) Unclassified report SC-78801 Photographic film is one of the best materials known for storing Photographic film is one of the best materials known for storing maximum information in the smallest amount of medium. Data maximum information in the smallest amount of medium. Data may be inserted in independent channels; it is therefore necessary may be inserted in independent channels; it is therefore necessary to know the limiting channel spacing so that the uniqueness of each to know the limiting channel spacing so that the uniqueness of each channel can be preserved. channel can be preserved. This memorandum describes a procedure to determine the limiting This memorandum describes a procedure to determine the limiting channel spacing. The method consists of contact-printing on a test channel spacing. The method consists of contact-printing on a test film the image from a mirror-surfaced, optically flat glass block. film the image from a mirror-surfaced, optically flat glass block. In the mirror surface, lines 42 Li wide are engraved with a variable In the mirror surface, lines 42 i wide are engraved with a variable spacing from 8. 5 lines/mm to 62. 5 lines/mm. The image is then Armed Services spacing from 8. 5 lines/mm to 62. 5 lines/mm. The image is then Armed Services scanned with a specular densitometer and the light transmission Technical Information Agency scanned with a specular densitometer and the light transmission Technical Information Agency recorded. The scanning aperture is 5 ji. UNCLASSIFIED recorded. The scanning aperture is 5 pi. UNCLASSIFIED (over) (over)

AD UNCLASSIFIED AD UNCLASSIFIED From the recording, the contrast ratio at any resolution, i. e., UNITERMS From the recording, the contrast ratio at any resolution, i. e., UNITERMS the ratio of contrast at a given resolution to that at a low resolution the ratio of contrast at a given resolution to that at a low resolution Photography (8.5 lines/mm) may be determined. This procedure is carried Photography (8. 5 lines/mm) may be determined. This procedure is carried Film out with different amounts of exposure, all film being developed out with different amounts of exposure, all film being developed Channel under constant conditions. A relationship is then expressed be- Channel under constant conditions. A relationship is then expressed be- Spacing tween light transmission through the image and the limiting res- pacing tween light transmission through the image and the limiting res- Densitomete olution for a contrast ratio (e. g., 0. 707). Data for several olution for a trast ratio (e. g., 0. 707). Data for severalLight transmission commercially available films are given. commercially available films are given. UNCLASSIFIED UNCLASSIFIED COT, O0= AD UNCLASSIFIED AD UNCLASSIFIED From the recording, the contrast ratio at any resolution, i. e., UNITERMS From the recording, the contrast ratio at any resolution, i. e., UNITERMS the ratio of contrast at a given resolution to that at a low resolution the ratio of contrast at a given resolution to that at a low resolution Photog h (8. 5 lines/mm) may be determined. This procedure is carried Photography (8. 5 lines/mm) may be determined. This procedure is carriedpy out with different amounts of exposure, all film being developed out with different amounts of exposure, all film being developed under constant conditions. A relationship is then expressed be- angunder constant conditions. A relationship is the n exp res sed be-r tween light transmission through the image and the limiting res- tween light transmission through the image and the limiting resolution for a contrast ratio (e. g., 0. 707). Data for several Ligholution for a co ntrast rati o (e.bg.,. 707). Data for severalnsmio commercially available films are given. commercially available films are given. UNCLASSIFIED UNCLASSIFIED