![Ulllted States Patent [19] [11] Patent Number: 5,771,109 Difrancesco [45] Date 0F Patent: Jun](http://data.docslib.org/img/0791511da90471fd4132eda2e9c8f0d9-1.webp)
US005771109A Ulllted States Patent [19] [11] Patent Number: 5,771,109 DiFrancesco [45] Date 0f Patent: Jun. 23, 1998
[54] METHOD AND APPARATUS FOR 5,537,203 7/1996 Carr ...... 356/236 [)IGITIZING FILMS USING A 5,548,120 8/1996 Parker et al...... 250/341.7 STROBOSCOPIC SCANNING SYSTEM FOREIGN PATENT DOCUMENTS
[75] Inventor: David DiFrancesco, EngleWood, Calif. 498945 1/1939 United Kingdom . 2011756 7/1979 United Kingdom H04N 3/36 [73] Assignee: PiXar, Richmond, Calif. 2025731 1/1980 United Kingdom ...... H04N 3/36 OTHER PUBLICATIONS [21] Appl. No.: 651,164 [22] Filed: May 17’ 1996 gilciggriA High Resolution Digital Film Scann IDS4000
[51] Int. Cl.6 ...... H04N 1/46 Laser Based Color Film Recorder System With GaAs [52] US. Cl...... 358/507; 358/506; 205/228 Microlaser, D- Difrancesco, 17—20, Jan- 1989 [58] Field of Search ...... 382/132; 358/474, High Resolution CCD Film Scanner For Special Effects 358/475, 480, 481, 486, 487, 491, 500, Applications, Mike Davis et al., unpublished. 506, 509, 510, 512, 501, 527; 355/32, 33, _ _ 37, Primary Examzner—ThoInas Lee Assistant Exammer—Jerome Grant, II [56] References Cited- Attorney , A 8 em, or Firm—Hecker & Harriman US. PATENT DOCUMENTS [57] ABSTRACT 3,584,147 6/1971 The present invention is a method and apparatus for digi 3,584,148 6/1971 Flory et al. .. . tiZing ?lm frames. The invention utilizes different colored 3,637,937 1/1972 DCVCSOII et al...... 340/680 Strobe housed in an integrating Sphere, instead of the 3,679,827 7/1972 BoltZ ...... 348/97 prior art ?lter and Shutter mechanism_ The invention’s 2/ {$305 egal' ' control system ?ashes each strobe light in sequence for a 4’255’764 32981 Héw‘zar 3443/98 predetermined time to expose a ?lm frame to various color 4’309’746 1/1982 362/259 components. The various color components of the ?lm 4’310’847 1/1982 Frohbach et a1_ 348/104 frame are projected onto a CCD array With the aid of a lens. 4319:2530 3/1982 R005 et at ______348/97 Each strobe light is ?ashed at a desired frequency and for the 4,330,793 5/1982 Stemme er a1, _ 348/104 predetermined time in order to saturate the CCD array With 4,495,516 1/1985 Moore et al. 348/104 the component of light corresponding to that strobe light. 4,623,929 11/1986 Johnson et a1- - 315/241 5 The color data corresponding to each color component are 4,681,427 7/1987 Hummer 355/32 passed to digital signal processors for processing and stor 4’688’O9g 8/1987 Funston 348/96 age. In one embodiment of the invention, the strobe lights j’gig’gés girglirllsfnner ' are red, green, and blue strobe lights. 5:155:586 10/1992 Levy etal. .. 348/104 5,249,056 9/1993 Foung et al...... 348/97 57 Claims, 5 Drawing Sheets U.S. Patent Jun. 23, 1998 Sheet 1 0f 5 5,771,109
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FIG. 6 602 START
FLASH RED STROBE LIGHT 604 AT 75HZ FOR ONE / 608 SECOND TO SATURATE THE CCD ARRAY
U PROCESS TRANSFER THE RED RED COLOR COLOR DATA T0 DIGITAL f 606 DA TA SIGNAL PROCESSORS
FLASH GREEN STROBE LIGHT A7 8H2 FOR ONE SECOND r0 SATURA r5 / 5'0 674 THE CCD ARRAY
PROCESS TRANSFER THE GREEN GREEN COLOR COLOR DATA TO DIGITAL DA TA SIGNAL PROCESSORS \CIZ
FLASH BLUE STROBE LIGHT AT JOHZ FOR ONE SECOND TO SATURATE 620 THE CCD ARRAY
PROCESS BLUE TRANSFER THE BLUE COLOR COLOR DATA T0 DIGITAL /- 678 DA TA SIGNAL PROCESSORS
1 DIGITIZE NEXT FRAME \ 622 5,771,109 1 2 METHOD AND APPARATUS FOR chroniZation devices. The ?lter sWitching mechanism and DIGITIZING FILMS USING A the shutter system also require regular and costly mainte STROBOSCOPIC SCANNING SYSTEM nance. In addition to all of these disadvantages, the prior art ?lter sWitching mechanism is sloW. Three different ?lters BACKGROUND OF THE INVENTION must be sWitched to digitiZe each ?lm frame. A typical full 1. Field of the Invention length ?lm has thousands of ?lm frames. Thus, digitiZing the The present invention relates to the ?eld of ?lm digitizing entire ?lm can take hours longer just for the time consumed apparatus. in sWitching the three red, green, and blue ?lters. 2. Background Art Another dif?culty With the prior art ?lm digitiZing appa ratus is that the light produced by light source 104 is a Film digitiZing apparatus are used to transform images from ?lm frames to digital data for storage and display by “parallel light.” In other Words, the light generated by light source 104 is not uniformly distributed over ?lm plane 102. computer systems. FIG. 1 shoWs the functional blocks of a prior art ?lm digitiZing apparatus 100. A light source 104 Typically, the intensity of the light is larger in the center of ?lm plane 102. This results in a non-uniform exposure of emits White light toWard ?lm plane 102 Which holds a ?lm 15 frame (not shoWn). A colored ?lter 105 is placed betWeen CCD array 110 and in a delay in saturating the edges of the light source 104 and ?lm plane 102. Filter 105 is typically CCD array. Sometimes additional optics or ?ber optic face plates are used to correct this non-uniform exposure of the a red, green, or blue ?lter and permits only one of these basic CCD array. HoWever, this increases cost and also results in colors to pass through. Alens 109 focuses onto a CCD array 110 the light component ?ltered by ?lter 105 (for example, loss of light in the system. the blue light component). The folloWing patents disclose ?lm digitiZing apparatus. During operation of the prior art ?lm digitiZing apparatus Flory (US. Pat. No. 3,584,147) discloses an apparatus for 100, the White light emanating from light source 104 is generating triggering pulses for actuation of a blue strobe ?ltered by colored ?lter 105. The component of light passing light at desired times. According to Flory ‘i147, light from the blue strobe light is transmitted forWard to a camera through ?lter 105 exposes the ?lm frame held by ?lm plane 25 102. After passage of a short time CCD array 110 becomes through a ?lm frame, tWo dichroic mirrors, and a lens saturated With the color component of the ?lm correspond system. A continuous yelloW light is transmitted backWard ing to colored ?lter 105. For example, if ?lter 105 is a blue through the tWo dichromatic mirrors to a photo detector ?lter, the CCD array becomes saturated With the blue color Which develops the triggering pulses for actuating the blue component of the ?lm frame. The digitiZed color data are strobe light. Flory (US. Pat. No. 3,584,148) discloses an then fed from the CCD array to computer storage. apparatus for illuminating a ?lm frame several times by a As stated above, according to the prior art, light source strobe light operating at a predetermined rate. The apparatus images the ?lm onto a photosensitive surface. The apparatus 104 is a White light source. The prior art White light source includes rotating mirrors in the optical path to compensate 104 typically consists of continuous Wave xenon or halogen for the motion of the ?lm betWeen successive strobe light lamps. In order to expose CCD array 110 to the basic colors, 35 namely, red, green, and blue, three different colored ?lters ?ashes so that each ?lm frame is imaged onto the same are utiliZed. A red ?lter is used to pass through only the red photosensitive area. component of the White light. Likewise, a green ?lter is used Deveson et al (“Deveson”, US. Pat. No. 3,637,937) is to pass through the green light component, and a blue ?lter directed to an apparatus for producing video signals from a photographic ?lm. The Deveson apparatus attempts to over is used to pass through blue light component, of the White 40 light emanating from light source 104. Each ?lter 105 is come overexposure or underexposure of the photographic inserted betWeen ?lm plane 102 and light source 104 (or ?lm such that the video signals accurately represent the alternatively, betWeen ?lm plane 102 and lens 109) for a image on the photographic ?lm. Deveson uses a “variable predetermined period of time. The ?lter is then removed and density light ?lter” to vary the illumination of the ?lm as a replaced With one of the other tWo ?lters for a predetermined 45 part of its apparatus. period of time. Thus, each one of the red, green, and blue BoltZ (US. Pat. No. 3,679,827) is directed to an apparatus ?lters is sequentially inserted, removed, and replaced With a used in continuous ?lm projection systems. BoltZ attempts different colored ?lter. This ensures that only one of the three to maintain a light replica of a ?lm frame stationary on a colors red, green, or blue is passed through to CCD array photosensitive camera tube While the ?lm frame is in 110. According to the prior art, a shutter system is placed motion. In order to accomplish this, BoltZ uses tWo partially betWeen the light source 104 and ?lm plane 102. light transmissive and partially light re?ective devices in the Alternatively, the shutter system is placed betWeen ?lm optical path betWeen the ?lm frame and the camera tube. The plane 102 and lens holder 109, or betWeen lens holder 109 devices are rotated such that the light replica of the ?lm and CCD array 110. frame is transmitted to the camera tube When the ?lm frame The prior art requirement of using different colored ?lters 55 is in the center of a ?lm gate and also When the ?lm frame in conjunction With a shutter system results in a number of is about to leave the ?lm gate. disadvantages. For example, the prior art ?lm digitiZing Frohbach et al (“Frohbach”, US. Pat. No. 4,310,847) apparatus requires a complicated mechanism for insertion discloses a ?lm scanning system. According to Frohbach, an and removal of ?lters. The prior art also requires precise image is recorded on ?lm at a television ?eld rate. Aportion timing for the shutter system in order to control the period of the ?lm corresponding to a line in the image is illumi of time during Which the CCD array is exposed to each color nated. The illuminated portion is decomposed into its color component. The shutter system must also be synchroniZed components. The decomposed light from the illuminated With the ?lter sWitching mechanism in a manner such that portion of the ?lm is imaged onto scanning photosensitive While the ?lters are being sWitched White light is blocked arrays. The scanned signals provided by the photosensitive from exposing the CCD array. Accordingly, the prior art ?lm 65 arrays are recorded and used to provide television signals. digitiZing apparatus requires complicated and costly ?lter Moore et al (“Moore”, US. Pat. No. 4,495,516) discloses sWitching mechanism, shutter system, and timing and syn an apparatus for producing video signals from a ?lm’s 5,771,109 3 4 image. The apparatus has a CCD image sensor having an the prior art ?lter and shutter face plate mechanism. The integral color ?lter array. The CCD image sensor is illumi invention’s control system ?ashes each strobe light in nated With an image from the ?lm. A signal processor color sequence for a predetermined time to expose a ?lm frame to corrects the signals produced by the sensor. various color components, all With Lambertian distributed Johnson et al (“Johnson”, US. Pat. No. 4,623,929) dis ?at ?elds. The various color components of the ?lm frame closes an improved simmer current circuit for a strobe light are projected onto a CCD array With the aid of a lens. Each in a video player. The strobe light is used to ?ash illuminate strobe light is ?ashed at a desired frequency and for the a photographic ?lm for a solid state image sensor. A current predetermined time in order to saturate the CCD array With sync circuit is used for draWing a simmer current from the the component of light corresponding to that strobe light. strobe light to maintain an arc in the strobe light betWeen 10 The color data corresponding to each color component are sensor-illuminating ?ashes. The improved simmer current passed to digital signal processors for processing and stor circuit ensures that the strobe light ?ashes only When the age. In one embodiment of the invention, the strobe lights simmer current is off, thus reducing electromagnetic inter are red, green, and blue strobe lights. ference and increasing the quality of the video signal gen erated by the video player. 15 BRIEF DESCRIPTION OF THE DRAWINGS Funston (US. Pat. No. 4,688,099) discloses a video FIG. 1 is a functional block diagram of a prior art ?lm player having a strobe light for ?ash illuminating a photo digitiZing apparatus. graphic ?lm for a solid state image sensor. Adetector circuit FIG. 2 illustrates an embodiment of the invention’s ?lm produces a control signal that is a function of Whether the digitiZing apparatus. illumination of the image sensor is above or beloW a 20 FIG. 3 is an illustration of the integrating sphere accord saturation level of the image sensor. A microprocessor ing to the present invention. adjusts an exposure level signal in accordance With the control signal. The adjusted exposure level signal in turn FIG. 4 is an overvieW of the control system of the present adjusts the intensity and duration of the strobe light ?ash invention. such that the image sensor is illuminated to a level close to 25 FIG. 5 illustrates the control system of the present inven its saturation level. tion. Levy et al (“Levy”, US. Pat. No. 5,155,586) discloses a FIG. 6 illustrates one cycle of the ?lm digitiZing operation system for performing ?are correction on digitiZed color of the present invention for a single ?lm frame. ?lm images. Each digitiZed image may include red, blue, and green color components corresponding to the ?lm. Flare 30 DETAILED DESCRIPTION OF THE correction signals are digitally generated and used to com INVENTION pensate for undesired luminance variations from frame to A method and apparatus for digitiZing ?lm frames using frame for each color component. a stroboscopic scanning system is described. In the folloW Foung et al (“Foung”, US. Pat. No. 5,249,056) discloses 35 ing description, numerous speci?c details are set forth in an apparatus for generating video signals from a photo order to provide a more thorough description of the present graphic ?lm. The apparatus includes a ?lm transport for invention. It Will be apparent, hoWever, to one skilled in the advancing or reWinding the ?lm to position a ?lm frame at art, that the present invention may be practiced Without these a ?lm gate. The apparatus also includes an image projector speci?c details. In other instances, Well-known features have Which detects When a ?lm frame is positioned at the ?lm 40 not been described in detail so as not to obscure the gate and ?ashes a strobe light to project an image of that invention. frame. The apparatus also has a video pickup system Which The present invention is a unique method and apparatus receives the projected image and generates video signals for digitiZing ?lm frames. The invention overcomes the prior corresponding to the image. art disadvantages of using three colored ?lters and the None of the patents discussed above has overcome the 45 complications associated With the insertion and sWitching prior art’s problem of sloW, costly and complex ?lm digi ?lters upon passage of predetermined time intervals. The tiZing apparatus. More speci?cally, none of these patents has invention also overcomes the need for using a shutter and addressed the prior art’ reliance on the ?lter sWitching synchroniZing it With the ?lter sWitching system to block mechanism and the shutter and optics system discussed unWanted light from passing through to the CCD array. The above. invention also overcomes the need for ?eld ?attening optics An article entitled “Laser Based Color Film Recorder or ?ber face plates for even distribution of light over the ?lm System With GaAs Mircrolaser” by David DiFrancesco, plane. printed in the Proceedings of SPIE-The International Society FIG. 2 shoWs an embodiment of the invention’s ?lm for Optical Engineering, 17—20 January 1989, pages 16—26 digitiZing apparatus 200 using the invention’s stroboscopic discusses use of red, green, and blue laser beams in color 55 scanning system. Instead of the prior art’s White light source ?lm recording. HoWever, the article does not suggest a Way 104, the invention uses an “integrating sphere” 204 as the to overcome the prior art’s problem of sloW, costly and source of light for the ?lm digitiZing apparatus. A?lm plane complex ?lm digitiZing apparatus. Furthermore, the article 202 is utiliZed to hold a frame of ?lm (not shoWn) during the does not address the prior art’s reliance on the ?lter sWitch operation of the ?lm digitiZing apparatus. The double ing mechanism and the shutter system discussed above. 60 arroWed line 212 shoWs the length of one side of the aperture Thus, there is need in the art for a faster, simpler, more of ?lm plane 202. In one embodiment of the invention the reliable, and less expensive ?lm digitiZing apparatus. aperture is a square With each side having a length of 35 millimeters. A “?lm transport” 206 is used to move the ?lm SUMMARY OF THE INVENTION as it is exposed to the light emitted from integrating sphere The present invention is a method and apparatus for 65 204. A “dove tail” 208 is used for holding lens holder 209 digitiZing ?lm frames. The invention utiliZes different col and CCD camera 210. CCD camera 210 contains an array of ored strobe lights housed in an integrating sphere, instead of CCD’s (not shoWn in FIG. 2) Which is exposed to light 5,771,109 5 6 emitted from integrating sphere 204 through a ?lm frame 08/664,266 ?led on Jun. 11, 1996, assigned to the assignee placed in ?lm plane 202. of the present application and incorporated herein by refer Discussing the structure of the invention’s apparatus in ence. The invention may also utiliZe a column of CCD’s, more detail, instead of the prior art’s ?lter and shutter instead of the array of CCD’s discussed above. In another mechanism discussed above, the invention utiliZes integrat embodiment of the invention, photo-sensitive sensors other ing sphere 204 Which houses four strobe lights. One red than CCD sensors are utiliZed. strobe light, one green strobe light, and tWo blue strobe FIG. 4 shoWs a system level overvieW of the present lights (a single blue strobe light, instead of tWo blue strobe invention, and the control system utiliZed to control the strobe lights in the integrating sphere and other components lights, may also be used as another embodiment of the 10 of the present invention. Block 404 is a block diagram invention). representation of the integrating sphere (including the four Reference is made to integrating sphere 204 shoWn in strobe lights). Block 406 is a block diagram representation FIG. 2. Integrating sphere 204 is shoWn in more detail in of ?lm transport 206. Block 410 is a representation of CCD FIG. 3. Like numbers in FIGS. 2 and 3 refer to like camera 210 Which houses a CCD array (not shoWn). Block components. Referring to integrating sphere 204 shoWn in 15 411 is a representation of a control system utiliZed to control FIGS. 2 and 3, in one embodiment of the invention four integrating sphere 404, ?lm transport 406, and CCD camera strobe lights are placed along meridian 232 of the integrating 410. Control system 411 controls the ?ashing sequence and sphere (manifestly, the exact location of the four strobe the frequency of ?ashing of the four strobe lights in inte lights can be varied Without departing from the scope of the grating sphere 404. Control system 411 also commands and present invention). Meridian 232 lies in a plane that is controls CCD camera 410 Which delivers digital image data perpendicular to a plane containing equator 216. Each strobe to control system 411 for storage and processing. light lies along meridian 232 in a plane parallel to the plane Control system 411 is shoWn in more detail in FIG. 5. of equator 216. Each strobe light is pointed toWards the CPU card 521 typically includes 32 megabytes of memory, inside of the integrating sphere and is housed in an opening a single 75 MHZ Sun SPARC II With cache and a Sbus video in the outer surface of the integrating sphere. Each opening card (for example, a generic Sun brand) for displaying has a diameter of 25 millimeters. Thus, four openings each video. CPU card 521 also includes tWo RS232 ports 507. With a diameter of 25 millimeters are distributed along One of the ports is coupled to, and controls, CCD camera meridian 232. TWo of the openings (openings 222 and 224) 510 (shoWn as CCD camera 210 in FIG. 2). CPU card 521 are located on each side of the plane of equator 216 and are communicates With other components of control system 411 equidistant from the equator. The other tWo openings (220 via VME bus 525. A monitor, mouse, and keyboard (none of and 226) are also on opposite sides of the equator and are Which is shoWn in FIG. 5) are also attached to CPU card 521. equidistant from the equator. As an example, in one embodi A disk drive 505 is connected to CPU card 521 via a SCSI ment of the invention a red strobe light is placed in opening bus. Block 529 represents an optional Ethernet connection 220, a green strobe light in opening 224, a blue strobe light for moving image data from the control system for use by in opening 222, and another blue strobe light is placed in 35 other users. A Green Spring VME/IP interface card 522 is opening 226. coupled to VME bus 525. Interface card 522 provides an Integrating sphere 204 also includes a rectangular aper interface for up to four IP (Industry Packs) cards to VME bus ture 230 at the apex of meridian 214. The plane of meridian 525. IP 506 controls ?lm transport 206 through an optically 214 is perpendicular to a plane containing meridian 218. isolated relay panel. IP 504 controls the four strobe lights of Meridian 232 (on Which the strobe lights are placed) is at 45° integrating sphere 204. angle With respect to meridian 214. Meridian 232 is thus Block 523 represents a RAMIX RM-140B memory card. half-Way betWeen meridians 214 and 218. The light gener Memory card 523 is a dual port memory having 64 mega ated by the strobes and re?ected from the internal surface of bytes of storage space. Memory card 523 can be accessed by integrating sphere 204 is focused onto ?lm plane 202 by either VME bus 525 or VSB bus 526. VSB bus 526 is used passing through aperture 230 With Lambertian distribution. 45 to couple memory card 523 to Digital Signal Processor The internal surface of integrating sphere 204 is coated by (DSP) 524, and move processed data out of DSP 524 to a substance comprised of rare-earth metals for increased memory card 523. From memory card 523, the processed re?ectivity. The coating increases the radiance of the internal data is moved to CPU card 521 via VME bus 525 for ?nal surface of the integrating sphere so that the internal surface processing and storage. Memory card 523 is used both as a is approximately ninety to ninety seven percent ef?cient in large buffer betWeen DSP 524 and CPU 521, and also as a re?ecting the light provided by the strobes. Integrating quick means of transferring data from DSP 524. In control sphere 204 provides a Lambertian distribution of light for system 411, data rates out of DSP 524 are about 2 Mb per exposing a ?lm frame to the CCD camera. This overcomes second on VME bus 525, and about 15 Mb per second on the prior art’s need to diffuse and “make ?at” a parallel light VSB bus 526. It is noted that DSP 524 comprises tWo source for exposing the ?lm frame to the CCD camera. 55 Spectrum VME DSP carrier boards, and each board includes In the preferred embodiment of the invention, ?lm trans tWo DSP processors. The DSP processors are typically Texas port 206 is a modi?ed Wide-body version of the Albert Instruments TMS320C40 DSP chips, at either 40 MHZ or 50 HoWell design circa 1911 Which is a cam operated, pin MHZ clock speeds. registered, ?lm shuttle mechanism used in the optical cam Block 527 is an interface block betWeen a Photometrics era manufacturing industry. The shuttle mechanism and ?lm CCD camera 510 and DSP 524. This interface attaches to plane 202 can accommodate various ?lm formats such as buffered COMM ports on the Spectrum VME DSP carrier “35 Academy,” “65 mm,” and “35 Vistavision”(“8 Perf”). boards. The data rate on the buffered COMM ports is about The invention utiliZes a 75 millimeter Rodenstock lens 15 Mb per second. The maximum data rate from the placed in lens holder 209. The CCD camera 210 (FIG. 2) Photometrics CCD camera is 2 Mb per second. Finally, as holds a CCD array With a siZe of 3>