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Hlf/ll Report No. 210 
 
 ynait 
 
 coo- 1018- 109U 
 
 
 ON THE APPLICATION AND DESIGN OF AN IMAGE STORE 
 
 by 
 
 Sylvian R. Ray 
 
 August 22, 1966 
 
 DEPARTMENT OF COMPUTER SCIENCE • UNIVERSITY OF ILLINOIS • URBANA, ILLINOIS 
 
Report No. 210 
 
 ON 'IKE APPLICATION AND DESIGN OF AN IMAGE STORE 
 
 by 
 
 Sylvian R. Ray 
 
 August 22, 1966 
 
 Department of Computer Science 
 University of Illinois 
 Urbana, Illinois 6l801 
 
 (Supported in part by Contract AT(ll-l)-10l8 with the U.S. Atomic Energy 
 Commission and the Advanced Research Projects Agency.) 
 
Digitized by the Internet Archive 
 in 2013 
 
 http://archive.org/details/onapplicationdes210rays 
 
ACKNOWLEDGMENT 
 
 Professor Bruce H. McCormick and Mr. Robert Amendola have 
 contributed many valued ideas to this paper. Mrs. Letitia A. Prendergast 
 prepared the illustrations for this report. 
 
SUMMARY 
 
 The value and use of an image store is dismissed in the context of its 
 application to an Information Resource Center: an information retrieval system 
 incorporating a pattern-oriented general purpose computer and remote video 
 communication network. 
 
 With the proposed system configuration., text is stored only once - in 
 low cost, high-introduction-rate image form. Indexing research, providing 
 indexing in depth where required, and information reorganization may then proceed 
 on a large scale without further recourse to external data handling. 
 
 Ihe j.se f a remote video communications net contributes a complication 
 to the global system design which is rooted in channel capacity economics. In 
 particular, the information content of stored images needs adjustment to match 
 channel capacity, a problem which can be resolved by format control during 
 original loading of the image store. 
 
 Finally, two macrodesigns for image stores with different access times 
 and storage capacities are sketched. 
 
 -1- 
 
1 . INTRODUCTION 
 
 The emergence of electronically accessible Information Resource 
 Centers sprinkled throughout the United States appears to be an increasing 
 certainty^ as hardware capability and systems knowledge continue to improve . 
 Various visions of the goal and the paths leading to it have been proposed by 
 Licklider [1], Clapp [2] and McCormick [3]° In addition., at least one working 
 conference, INTREX [h] has been devoted to planning an experimental program 
 directed toward similar objectives . In general terms, an Information Resource 
 Center consists of a library-like information collection, with facilities to 
 encourage interaction between all participants of the collection.. The center 
 is further augmented by an evolving capability for fact retrieval and possibly 
 facilities for on-line control of experiments and the processing of experimental 
 data. 
 
 The present paper summarizes the system specifications for the design 
 of the library-like aspects of an Information Resource Center and proposes 
 alternate image store designs which satisfy these requirements. The term 
 "library-like" refers to document-type data which includes books, journal articles, 
 picture and map files but excludes some forms cf numerical experimental data and 
 other highly structured data. 
 
 -2- 
 
2. SYSTEM DESIGN 
 
 Limiting our purview to documents, as normally construed, the required 
 system hardware consists of four major components:* 
 
 1) a general purpose computer with special facility for high-volume 
 processing -- e.g. a machine of the ILLIAC III class. 
 
 2) a bank of photographic microimage stores. 
 
 3) a bank of semirandom access bit store -- e.g. magnetic disk storage. 
 
 h) an extensive communications network with remote video, as well as 
 low-speed digital, intercommunication between users and the central 
 equipment. 
 
 System macrooperations consist of insertion of images into photographic 
 image store and insertion of basic index data (title, author, image store address, 
 etc.) into bit store. A normal user types his search query into the system, the 
 computer generates the image store addresses of responsive documents, and these 
 documents may then be viewed or copied after transmission of the video image. 
 
 The image processing facility proposed above will, in addition, be 
 utilized by research workers and system programmers to investigate machine index- 
 ing methods and to evolve deeper indexing for more important and frequently used 
 documer.ts . 
 
 tal distinction is made between text in image store and the 
 index in bit store. This dichotomy is essential to high speed index searching as 
 well as flexibility in altering the length of the index. + 
 
 Secondly, the contemplated system provides for economical, high volume, 
 rapid introduction of basic data by the provision for image format insertion. 
 The objective is that this initial introduction shall be the only introduction 
 of any particular piece of original source data. The image data will have 
 
 * 
 
 All of these components except (2) are well advanced in design, under 
 
 construction, or being purchased commercially at the University of Illinois. 
 On this point, I heartily agree with Van Dam and Evans [5]- 
 
 -3- 
 
sufficient resolution that character recognition processing can be successfully 
 performed -- the processing capacity of the central computer must be adequate to 
 the task. As documents of special interest are identified and algorithms for 
 index development sharpen, deeper and more precise indexes can be evolved without 
 return to original documents. Furthermore, any qualified and interested researcher 
 can reorganize, regroup, and synthesize information from the system into new 
 image formats to be introduced into the system. This facility to work directly 
 with photographic images of documents makes possible a number of the objectives 
 proposed by Licklider while abrogating his pessimistic forecast on the rate of 
 introduction of documents into the system. 
 
 The third remark concerns the technical nature of images introduced 
 into storage. In every available or proposed image store, design is based on 
 the assumption that images are viewed and/ or photocopied locally. Such a system 
 would be obsolete before it became operational. Facilities for image transmission 
 are essential. The problem however is that the achievable resolution of any 
 practical television system is not adequate to reproduce most text pages to 
 human readability standards. The limitation is imposed either by the camera/ 
 monitor capabilities (presently, 1275 lines maximum) or by channel bandwidth. 
 In the present commercial market, the camera sets resolution limits but even if 
 this limit is eased, the time required to transmit one frame over available 
 communication channels will set the next barrier. 
 
 Considering the economics and limitations of transmission equipment, 
 monitors, etc., it is necessary that each image in the image store correspond to 
 a unit transmittable frame. One solution is to reformat original text material 
 to conform to transmittable resolution standards. In many cases, reformatting 
 only amounts to division of a page into two images, one for upper half and 
 another for lower half. In other cases, computer control of the recording camera 
 system will be necessary. 
 
 -k- 
 
3- THE IMAGE STORE: DESIGN CRITERIA 
 
 We discuss next some criteria which affect the design of the image 
 store itself. 
 
 3-1 Image Access Time 
 
 In any multiple user on-line system, once the files have been organized 
 in the optimum practical manner, the residual limitation on the rate of servicing 
 users (or the total number of users who can be served in tolerable waiting time) 
 is a function of image access time. A maximum access time to one image of about 
 one second seems a reasonable goal. That law of nature, the trade-off of access 
 time for capacity, will affect this goal by factors of two to four. 
 
 3-2 Capacity 
 
 In order to service even one scientific research field, a minimum 
 
 count of the order of 10 pages is indicated. For example, the EURAT0M infor- 
 
 mation system servicing only the field of nuclear science presently counts 4.10 
 
 * 
 documents averaging perhaps 10 to 20 pages per document. 
 
 R o 
 
 Stores of 10 to 5-10 images would find application in regional or 
 
 national centers. 
 
 In summary, the widest range of application would be served by an 
 image store designed for minimum capacity of 10 images and economically 
 
 Q 
 
 expandable to 10 images. Larger storage requirements could be served by 
 multiple storage units. 
 
 L Rolling, private communication. 
 
 ■5- 
 
3 »3 Image Editing, Insertion and Readout 
 
 The readout system for stored images must satisfy several conditions: 
 
 1) Output image resolution must be adequate for human viewing without 
 strain. 
 
 2) Images must be transmittable to remote stations. 
 
 3) Output resolution and signal/noise ratio must be adequate for 
 mechanical recognition without extravagant noise reduction, line 
 thinning, and contrast enhancement procedures . 
 
 k) Image quality must be sufficient that file images edited by 
 
 electronic "scissors-and-paste" can be reintroduced into the file. 
 
 Clearly, there is a substantial economic advantage in using a standard 
 or near- standard television system for readout and image distribution. 
 
 Regarding condition (l), experimental tests of text displays on high 
 resolution television systems were performed. The results show that between 
 10 (minimum) and 15 (maximum) TV lines per gross character line height provide 
 readable resolution of text. This assumes that horizontal resolution, per inch, 
 is approximately equal to vertical resolution of the TV system. The minimum 
 quantity, 10, corresponds to a barely readable image quality while the maximum 
 would be acceptable to a severe critic. Table 1 presents calculated resolutions 
 required for three cases. 
 
 These results can be interpretated as asserting that one whole document 
 page can be legibly reproduced by a 1029 line television system (a readily 
 available type) for a substantial fraction of documents. However, there remain 
 a non-negligible number of special cases (footnotes, figures with small captions, 
 etc.) for which one page-one frame resolution is inadequate. One u iversally 
 valid solution to this problem is to edit (reformat) the original image. 
 
 Generally, reformatting under machine control is much less time 
 consuming then complete character recognition, but the actual complexity of 
 format control logic can be determined only after sampling a representative 
 range of practical cases. 
 
 -6- 
 
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The question of reformatting affects the image store design, per se, 
 only to the extent that the capacity cannot be equated strictly to number of 
 document pages. The system as a whole, however, is strongly affected by the 
 transmission considerations, as noted in the preceding section* 
 
 Turning to condition 2 - transmittability - there is certainly no 
 question of the basic suitability of television systems for both local and 
 remote transmission and distribution. There are several compromises which 
 must be made in the outlying system due to bandwidth limitations. However, 
 if the image store output per se is a high-resolution video signal, the signal 
 can be transmitted and converted readily to fit various bandwidth limitations. 
 
 We have little explicit data bearing upon condition 3 at present. 
 Experience from recognition experiments on non-character data suggests that 
 if the readout image is visually unambiguous in the absence of context, then 
 mechanical recognition will entail no presently unkown algorithms. 
 
 The fourth condition we wish to impose is the ability to edit images 
 retrieved from store and reinsert edited images into store. For iterative 
 application of the editing function to be possible, it is sufficient that 
 resolution of the stored image be non-decreasing during each edit operation. 
 We propose tentatively that the edited image be subjected to contrast enhancement 
 and noise reduction (i.e. digital filtering in the image processor), then 
 recomposed on a very high resolution flying-spot scanner and photographed. 
 Reduction to final microform for reinsertion in the image store employs only 
 normal photographic techniques. 
 
 -8- 
 
3°h Storage Medium and Technique 
 
 The storage media which are candidates for the present application 
 are (l) silver process film and (2) photochromic film. The only advantage of 
 presently available photochromic film is its high resolution and its partial 
 reversibility. Unfortunately, in addition to its monostability, the reversibility 
 is only partial which make photochromies unsuitable for continued reuse. 
 Silver film capable of resolution into ultraviolet wavelengths (e.g., Kodak 
 SOI 56) adequately satisfies practical resolution requirements. The principal 
 disadvantage of silver film is its irreversibility, making it suitable for 
 permanent storage only. In fact, the non-erasibility of the storage medium 
 may be viewed as an advantage in a system exposed to inexperienced users. 
 Therefore, the choice of a presently available media favors silver film. 
 
 The two major contenders for storage technique are (l) visual image 
 and (2) holographic representation* At present, no compelling advantages for 
 holographic techniques in this application have appeared, although the promise 
 of small economic and packing density advantages is clear. Hence, the visual 
 image storage technique remains a strong contender. 
 
 3»5 Image Size 
 
 "What shall be the size of the recorded microimage? The following 
 factors enter into the answer: 
 
 l) The stored image resolution should be substantially greater than 
 that of the readout system. Choosing the ratio, (stored image 
 re solution/ TV" system resolution) = 2 results in stored image 
 resolution = 2000 TV lines (minimum) . Approximately 1000 x 1000 
 wavelengths of the recording/ readout illumination is the 
 corresponding image size. Using light of \ = 0.5 jum, the minimum 
 theoretical image size to avoid degradation by diffraction is 
 0-5 x 0.5 ran- Experimental studies by Altman and Zweig [6] 
 support this value as a reasonable minimum for image content proposed 
 here with a high-quality, perfectly focussed microscope as the 
 optic system. 
 
 -9- 
 
2) The stored image size should not be so large that the total 
 
 film volume unduly enlarges the storage volume, hence adversely 
 affecting access time. One can readily show that even the smallest 
 
 o 
 
 achievable image size results in awkward storage volumes for 10 
 
 *- 
 images , especially after segmentation into practical card/ disk units 
 
 When the quality and availability of readout optics and degradation of resolution 
 by focus tolerance are considered, the image size must be relaxed from the minimum 
 stated above. Experimental results show that 1-5 mm microimages provide 
 adequate resolution. Therefore, the circular field of the image may range from 
 approximately 0-7 mm to 2 mm diameter. 
 
 3.6 Previous Related Systems 
 
 Before proceeding to more specific design concepts of an image store, 
 some features of systems previously developed or conceived should be reviewed. 
 
 Two image store systems based on card form have reached final develop- 
 ment status. One is the IBM WALNUT system [7] which employs a linear page 
 reduction of about 32:1 with random access to 10 images. The second system is 
 National Cash Register's PCMI (Photochromic Micro Image) store. 
 
 The problem of random access to cards has been solved in the following 
 systems: 
 
 1) IBM WALNUT 
 
 2) NCR PCMI 
 
 3) RANDOMATIC 3000 
 for photographic image cards, and 
 
 k) NCR CRAM 
 5) IBM 2321 DATA CELL 
 for magnetic bit storage. 
 
 As an indication, 3000 meters of 105 mm film. 
 
 See [8] for examples. 
 
 -10- 
 
Only two distinct card selection methods are represented. In one 
 technique represented "by the IBM 2321 Data Cell [8], the card addresses correspond 
 to physical locations. Access is accomplished "by rotating a circular card file 
 to align the desired card under a fixed-location pickup mechanism. This system 
 has the advantage of relatively fast access to a card - approximately 0.6 sees. 
 The principal disadvantage of this scheme is the capacity limitation imposed by 
 the maximum diameter and/or mass of the file which can accelerated and decelerated 
 within a specified time. Additionally, the arrangement does not lend itself 
 to expansion of capacity, once a circular file size is chosen, even if access 
 time degradation is permissible. 
 
 The second card selection method is the edge-notched card technique, 
 which is applied in the NCR systems as well as the Randomatic system. The 
 principal advantage of the edge-notch technique is that cards may be replaced 
 in store near the reading station by a standard operation. Thus, the distance 
 of a card from the reading station, hence its access time, tends to be inversely 
 related to its frequency of use. The operational value of this feature is not 
 entirely clear for the system under discussion here. The fundamental advantage, 
 however, of the edge-notched card selection technique is that system capacity 
 can be increased with, at worst, linear loss in access time. 
 
 -11- 
 
k. IMAGE STORE 
 
 k.l Design A 
 
 Design A is an adaptation of the IBM 2.321 Data Cell store [8] and the 
 Walnut store. The basic file consists of 10 cells mounted to form the periphery 
 of a cylinder. {See Figures land 2.) Each cell holds 20 subcells; each subcell 
 contains 10 film strips of 70 mm film. Each film strip in a subcell is distin- 
 guished by a coding tab in one of 10 standard positions extending along its 
 upper edge, and a hole in standard position for all strips. 
 
 4.1.1 Readout 
 
 Selection of a single film strip corresponds in detail to the IBM 2321 
 system. The array is slewed hydraulically to bring a card into position under 
 a pull-up mechanism. Separation fingers spread the cards of the subcell to free 
 the selected card. As the card is pulled up, a set of opaque fiducial marks, 
 one mark per image row are counted by a fiber optic-conducted illumination to 
 a photomultiplier . Pull-up is disengaged and vacuum clamping selected when the 
 desired image row is reached. 
 
 At this point, the vacuum clamp plate should be capable of establishing 
 the selected image row position to within + 1 milliinch (in the direction 
 orthogonal to film surface) with respect to a fly's eye lens having one lens to 
 each image in the row. While the foregoing selection proceeds, illumination 
 is selected to one of 50 optic fibers, one per column of images, to illuminate 
 the desired image of the row. All fly's eye lenses focus their associated images, 
 only one of which is illuminated, on the face of a high-resolution vidicon read- 
 out tube . 
 
 The spacing between microimages actually increases in proportion to 
 horizontal distance from film center, thus allowing all images to be directed 
 toward a common location, namely the center of the vidicon camera tube. 
 
 -12. 
 
The capacity of this system is: (10 cells) x (20 subcells) x (10 strips) 
 
 = 2000 film strips. A useful area/ strip of 50 mm x 250 mm can be contemplated. 
 
 3 3 
 
 Therefore, with 1 mm diameter per image, the storage capacity is 2-10 • 12 • 5 ' 10 
 
 = 25 M images. With 1-5 mm diameter, this capacity is reduced to 11 M images. 
 
 This system can be expected to perform worst case random access in 
 approximately 750 milliseconds, including an allowance of 100 milliseconds 
 (3 frames of 30 frame/second television) to enhance signal/ noise ratio. 
 
 This design falls into the lower capacity, higher-access speed region 
 relative to our specification of system requirements. 
 
 U.2 Design B 
 
 This design (see Figure 3) is based on the edge-notched card needle- 
 sort technique, in which respect it is similar to the NCR CRAM strategy. 
 
 Cards are formed of 300 mm strips of sprocketed 105 mm film, strengthened 
 perhaps by a thin Mylar jacket. Twelve address coding holes appear along the 
 upper film edge. Selection of one card is performed by 90 rotation, either 
 clockwise or counterclockwise, of the twelve semi-circular rods which pass through 
 the ceding holes of all U096 cards. (See Figure *+.) 
 
 The selected card falls under gravity plus vacuum forces into directing 
 guides which lead the card to engagement in a linear conveyor system. The card 
 is transported at 100 inches/ second velocity to the readout station. 
 
 As the card is pushed downward into the read station at the end of the 
 conveyer, its vertical position is monitored by a photomultipiier counter. When 
 the addressed image row is one sprocket-hole spacing from alignment with the 
 
 -13- 
 
readout optics, a pair of "spears" are selected which penetrate two sprocket 
 holes, stopping the film with the addressed image row within + 1 milliinch 
 from the readout station* Vacuum clamping and readout then proceed as in 
 Design A. (See section 4.1.) 
 
 Card replacement on the selection rods is accomplished by sprocket- 
 driving the card upward from the read station into the replacement mechanism., 
 The latter pushes the card onto the selection rods and returns to quiescent 
 position, leaving the replaced card nearest the readout station. 
 
 Estimating the active film width and length at 85 x 2^0 mm respectively 
 the total active area of one card module (U096 cards) is 87-10 mm . Hence, 
 for 1 mm field diameter, the capacity would be 87 M images. For 1.5 mm field 
 diameter, the capacity would be 38 M images. 
 
 Cycle time for this memory design is estimated at 1 to 1.6 seconds 
 for nearest and farthest card, respectively. 
 
 •x- 
 The set of spears, which halt film motion, relate by the vernier principle 
 
 to the film sprocket holes. (See Figure 5°) If the sprocket hole spacing 
 
 is a mm and the number of image rows between sprocket holes is v, then there 
 
 are v spears spaced o[(v-l)/v] mm uniformly along the sprocket hole line. 
 
 Spears occur in pairs, one member of each pair per line of sprocket holes. 
 
 To halt, the selected spear is driven forward with controlled pressure. The 
 tapered leading edge engages the sprocket hole. As the spear slides through, 
 the accurately shaped posterior establishes film position to high accuracy. 
 
 Based on 0.02 inch separation between cards) therefore, 7 feet extension of 
 cards . 
 
 -lU- 
 
BIBLIOGRAPHY 
 
 [1] Licklider, J. C R., Libraries of the Future . Massachusetts: Massachusetts 
 Institute of Technology Press, 19^5 • 
 
 Clapp, V., The Future of the Research Library . Illinois: University of 
 Illinois Press, I96U. 
 
 [3] McCormick, B. H., "Design Concepts for an Information Resource Center," 
 Department of Computer Science, University of Illinois, Urbana, Illinois 
 6l801. Report No. 203, May, 1966 . 
 
 [h] Overhage, C and Harman, R., INTREX . Massachusetts: Massachusetts Institute 
 of Technology Press, 1965- 
 
 [5] Van Dam, A. and Evans, D., "SHIRTDIF - A System for Storage, Handling, and 
 Retrieval of Technical Data in Image Format," Proc. of Amer. Doc. Inst ., 
 Vol. 1 (pp. 323-329), 196^. 
 
 Altaian, J. H., and H. J. Zweig, "Effect of Spread Function on the Storage 
 of Information on Photographic Emulsions," Photographic Science and 
 Engineering , Vol. 7, No. 3 (pp- 173-177), May- June, 1963- 
 
 Bradshaw, P. D., "The Walnut System: A Large Capacity Document Storage 
 and Retrieval System," Amer. Documentation , Vol. 13, No. 3 (pp- 27O-275), 
 July, 1962. 
 
 [8] Shubert, A. F. and Tong, Yang-Hu, "The IBM 2321 Data Cell Drive," AFIPS 
 Conference Proceedings, (pp. 335-3^+5), Spring, 1966. 
 
 -15- 
 
MAIN ARRAY- 
 (10 CELLS) 
 
 CELL- 
 (20 SUBCELLS) 
 
 FIGURE I. 
 
 DESIGN A: MAIN ARRAY AND SUBCELL 
 
 -16- 
 
PICKUP MECHANISM 
 
 ROW MARKS 
 
 SELECTED CARD 
 
 MICROIMAGE 
 
 LINEAR FLY'S EYE 
 
 ICON CAMERA 
 
 SUBCELL IN READOUT POSITION 
 
 FIGURE 2. DESIGN A: CARD AT READOUT STATION 
 
 -17- 
 
AIR 
 FLOW 
 
 REPLACE MECHANISM- 
 RETURN GUIDE- 
 
 REPLACE 
 MOTION 
 
 VIDICON CAMERA 
 
 FIGURE 3. DESIGN B: GENERAL MECHANISM LOCATION 
 
 -18- 
 
ADDRESS FOR CARD SHOWN- OOOIIIIOOOOI 
 
 SELECTION RODS 
 
 FRONT VIEW 
 POSSIBLE POSITIONS 
 
 I REST 
 
 (ONLY 90° ROTATION ALLOWED) 
 
 FIGURE 4 
 
 DESIGN B: EDGE NOTCHED CARD 
 
 -19- 
 
INTEGER MULTIPLE OF S 
 LINE OF READOUT OPTICS 
 
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 MAGE ROW (ADDRESS MODULO 4) 
 
 
 
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 CD 
 CD 
 CD 
 CD 
 CD 
 □ 
 CD 
 CD 
 CD 
 CD 
 CD 
 CD 
 
 CD — -i-SPEAR ROW 
 
 CD , SPEAR ROW I 
 
 SPEAR ROW 2 
 
 -r SPEAR ROW 3 
 
 •-SPACING = 3/4 -S 
 
 CD-t 
 CD 
 
 (ONE SET SPEARS 
 EACH SIDE) 
 
 0.1870 t .001 = S 
 
 IT 
 
 FILM CARD 
 
 TYPICAL CASE 
 S = 4.8 mm 
 IMAGE FIELD 
 DIAMETER = 1.2 mm 
 
 FIGURE 5. ILLUSTRATION OF VERNIER SPEARING 
 
 MECHANISM FOR 4 IMAGES PER SPROCKET-HOLE PERIOD 
 
 -20- 
 
JUN 2 1569