Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
  • H04N1/46—Colour picture communication systems
  • H04N1/56—Processing of colour picture signals
  • H04N1/60—Colour correction or control
  • H04N1/603—Colour correction or control controlled by characteristics of the picture signal generator or the picture reproducer
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
  • H04N1/40—Picture signal circuits
  • H04N1/407—Control or modification of tonal gradation or of extreme levels, e.g. background level
  • H04N1/4072—Control or modification of tonal gradation or of extreme levels, e.g. background level dependent on the contents of the original
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N5/00—Details of television systems
  • H04N5/222—Studio circuitry; Studio devices; Studio equipment
  • H04N5/253—Picture signal generating by scanning motion picture films or slide opaques, e.g. for telecine
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N9/00—Details of colour television systems
  • H04N9/11—Scanning of colour motion picture films, e.g. for telecine

Definitions

• the present invention relates in general to digitized color imagery photofinishing systems and is particularly directed to a mechanism for using a scene balance mechanism to calibrate the operation of a high resolution digital opto-electronic scanner.
• the dynamic range of photo-imagery input/output devices employed in photofinishing systems is considerably narrower than that of the image capture medium (photographic film), not all of the information contained on the film is reproducible.
• the device that inputs the film image to the photoprocessing system should be calibrated such that the principal subject matter of the image preferably falls within the linear portion of the response
• the input device a digital opto-electronic scanner
• the output device e.g. high resolution thermal printer
• the fundamental mismatch problem does not occur.
• very high resolution film scanners e.g. those having an imaging pixel array of 2028 x 3072 pixels, the response of which is resolved into sixteen bits per color per pixel
• the quantity of data produced per image is so large that it must be reduced for storage in a
• the above-referenced calibration and storage problem of conventional photofinishing systems is obviated by means of a new and improved digital imagery capture and storage mechanism which scans the image twice, the first scan being used to gather data to calibrate the scanner, and the second scan being used to capture and store a high resolution image.
• the scanner may be controlled to carry out a low resolution mode, prescan of the color photographic image of interest, thereby obtaining a low spatial resolution digitized image. (Because fewer pixels are scanned during the low resolution scan the low resolution pixel values may be encoded to a greater data precision.) This low
• a scene balance mechanism to determine how the response characteristic of the scanner's imaging pixel array sees the image and encodes its spatial content.
• a scene balance mechanism is meant an adjustment of image color balance based upon the scene content and the sensitometric characteristics (e.g. exposure, light source etc.) of the image being reproduced.
• the output of this analysis which represents the color balance content of the digitized image, is then used to adjust, or calibrate, the sensitivity parameters of the
• Adjustment of color balance is defined as adjusting the average red, green and blue image levels, so as to ensure that an image will have the appropriate color and neutral reproduction characteristics.
• the high resolution digitized image is then processed by the scene balance mechanism to map the image data into a digitized image having a reduced encoding resolution corresponding to that of an
• the essential information i.e. that which is necessary to reproduce a high quality image
• the image is scanned only once, at high spatial resolution and high digital resolution.
• the high spatial resolution image is then converted into a high digital, low spatial resolution image, which is processed to calibrate the scene balance mapping function. Namely, the processed data is used to calibrate the mapping of the originally digitized image into a reduced digital resolution (e.g. eight bits per pixel per color) framestore.
• a reduced digital resolution e.g. eight bits per pixel per color
• Figure 1 diagrammatically illustrates a photographic color film photofinishing minilab with which the scene balance-based digital imagery capture and storage mechanism of the present invention may be employed;
• Figure 2 is an imagery processing flow diagram of the scene balance based calibration and high resolution capture mechanism of a first embodiment of the present invention.
• Figure 3 shows the steps of an alternative calibration mechanism in which only a single (high resolution) scan is carried out.
• Figure 1 diagrammatically illustrates a photographic color film processing system (e.g.
• each high resolution captured image is preferably formatted and stored as a respective image data file containing a low, or base, resolution image bit map file and a plurality of higher resolution residual images associated with respectively increasing degrees of image resolution.
• a respective image data file containing a low, or base, resolution image bit map file and a plurality of higher resolution residual images associated with respectively increasing degrees of image resolution.
• successively increased resolution images may be recovered from the base resolution image.
• spatial data values representative of a high resolution (3072 x 2048) image scan of a 36mm-by- 24mm image frame of a 35mm film strip may be stored as a respective image data file including a base
• the base resolution image may be further sub-sampled to derive an even lower resolution sub-array of image values (e.g. on the order of 128 x 192 pixels) for use by the photofinishing operator in the course of formatting and storing a digitized image file.
• color photographic images such as a set of twenty-four or thirty-six 36mm-by-24mm image frames of a 35mm color film strip 10 are scanned by a high resolution opto- electronic color film scanner 12, such as a commercially available Eikonix Model 1435 scanner.
• High resolution film scanner 12 outputs digitally encoded data representative of the response of its imaging sensor pixel array (e.g. a 3072 x 2048 pixel matrix) onto which a respective photographic image frame of film strip 10 has been projected by an input imaging lens system.
• This digitally encoded data, or 'digitized' image is encoded to some prescribed resolution (e.g.
• sixteen bits per color per pixel that encompasses a range of values over which the contents of the scene on the color film may vary.
• the range of values is less than the density vs. exposure latitude of the film, but is sufficiently wide to encompass those density values that can be expected to be encountered for a particular scene.
• the quantity of data per image produced by such high resolution film scanners is so large that it must be reduced for storage and reasonably fast access in a practical sized framestore, which necessarily implies that some of the scene information in the digitized image will be discarded.
• the mechanism is used to map the digitized image into a set of lower resolution digital codes (e.g. eight bits per color per pixel), each of which has a resolution corresponding to the dynamic range of a digitized image data base (framestore).
• the database may be resident a in photofinishing workstation 14, which contains imagery application software through which the
• digitized image may be processed to achieve a desired base image appearance and configuration in the course of driving a high resolution thermal printer 16 to output a high quality color print.
• the digitized imagery data output by the high resolution film scanner is subjected to a code conversion mechanism of the type described in copending application Serial No. ___, filed ___, by T.
• the dynamic range of the digitized image database may be extended to permit shifting of encoded pixel values without 'clipping', and to provide a limited window of values into which extremely high reflectance image points may be encoded and stored.
• digital codes into which the high resolution imagery data output by the image scanner are mapped by the scene balance mechanism, are converted into a set of reduced-range digital codes of the same resolution as, but having a smaller range of image content values than the dynamic range of the digitized image data base.
• the code conversion mechanism operates to convert a maximum value of 100% white reflectance to an encoded value that is less than the upper limit of the dynamic range of the database to accommodate shifts in the digitized imagery data and allow for the placement of specular highlights that are beyond the 100% white reflectance maximum.
• the film scanner be calibrated such that the principal subject matter of the image falls within the linear portion of the response range of the scanner's imaging pixel array.
• a first embodiment of the present invention employs a calibration and high resolution capture procedure, diagrammatically
• image scanner 12 is controlled to carry out a low resolution mode, prescan of an image 10 of interest. Where the scanner has multiple resolution scan
• a 128 x 192 image is captured.
• a captured 128 x 192 pixel version of the image may be reduced to a very small sub-array
• This very low resolution (24 x 36) digitized image is then analyzed in step 102 by the scene balance mechanism to determine how the response characteristic of the scanner's imaging pixel array sees the image and encodes its spatial content.
• the scene balance mechanism determine how the response characteristic of the scanner's imaging pixel array sees the image and encodes its spatial content.
• the image processing result of which may be implemented as a set of look-up tables (LUTs), one for each RGB color) outputs three values, one for each color, which represent the color balance content of the digitized image.
• LUTs look-up tables
• step 103 using these values, the sensitivity of the scanner is calibrated, so that, during a subsequent high resolution scan of the image, the essential subject matter of the image will fall within the linear portion of the response range of the scanner's imaging pixel array. While the scene balance output values may be employed to effect vernier
• a respective offset code one for each of the color values, is added to the inputs of each scene balance look-up table in order to
• the scanner is controlled in step 104 to execute a high spatial resolution scan of the image. Since the scene balance LUTs have been translated in accordance with the output of the low resolution prescan, the high resolution digitized image will be mapped into the framestore such that essential image information (i.e. that which is necessary to obtain a high quality print) is captured and stored.
• Figure 3 shows the steps of an alternative calibration mechanism in which only a single (high resolution) scan is carried out.
• the image is scanned only once, at high spatial resolution and high digital resolution.
• the high spatial resolution image is then converted into a high digital, low spatial resolution image, which is processed to calibrate the scene balance mapping function. Namely, the processed data is used to calibrate the mapping of the originally
• the image is scanned to obtain a high spatial resolution (e.g. 2048 x 3072) image digitized, for example at sixteen bits per color per pixel, just as in the second, calibrated high resolution scan of the first embodiment.
• the high resolution image is spatially down-converted (decimated, filtered) to a relatively low spatial resolution digitized iamge, e.g. on the order of seven to twenty-four by ten to thirty- six pixels per frame, so as to reduce the computational intensity of the application of the high spatial resolution image to the scene balance mechanism through which that image is to be mapped into the framestore.
• This very low resolution (e.g. 24 x 36 pixel sub-array) digitized image is then analyzed in step 202 by the scene balance mechanism as in the first
• the scene balance mechanism outputs three values, one for each color, which represent the color balance content of the digitized image.
• step 203 using these values, the scene balance mapping function is calibrated (shifted), so that, during its application to the originally derived high resolution image, the essential subject matter of the image will be mapped in accordance with the linear portion of the response range of the scanner's imaging pixel array.
• a respective offset code one for each of the color values, may be added to the inputs of each scene balance look-up table in order to
• the high resolution digitized image is mapped into the framestore, in step 204, such that essential image information (i.e. that which is necessary to obtain a high quality print) is captured and stored.
• the present invention is able to successfully ensure that the essential subject matter of the image will fall within the linear portion of the response range of the scanner's imaging pixel array during a high resolution scan.
• the high resolution digitized image is then processed by the scene balance mechanism to map the image data into a digitized image having a reduced encoding resolution corresponding to that of an attendant framestore.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Facsimile Image Signal Circuits (AREA)
• Color Image Communication Systems (AREA)
• Reinforced Plastic Materials (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 1991
  • 1991-09-13 EP EP19910917567 patent/EP0503042A1/de not_active Withdrawn
  • 1991-09-13 WO PCT/US1991/006578 patent/WO1992005668A1/en not_active Application Discontinuation
  • 1991-09-13 CA CA002069332A patent/CA2069332A1/en not_active Abandoned
  • 1991-09-13 JP JP3516269A patent/JPH05502570A/ja active Pending

Non-Patent Citations (1)

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