System for distributing and controlling color reproduction at multiple sites

• US 20060197757A1
• Filed: 04/28/2006
• Published: 09/07/2006
• Est. Priority Date: 08/25/1997
• Status: Active Grant

• Current Assignee: RAH Color Technologies LLC
• Original Assignee: RAH Color Technologies LLC
• Inventors: Holub, Richard A.
• Granted Patent: US 7,710,560 B2
• Time in Patent Office: Days
• US Class Current: 345/207
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01J 2003/283 computer-interfaced
• CPC Class Codes: G01J 2003/2866 Markers; Calibrating of scan
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0224 using polarising or depolarising elements
• CPC Class Codes: G01J 3/0262 Constructional arrangements for removing stray light
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/1838 Holographic gratings
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01J 3/46 Measurement of colour; Colour measuring devices, e.g. colorimeters measuring colour temperature G01J5/60
• CPC Class Codes: G01J 3/462 Computing operations in or between colour spaces; Colour management systems
• CPC Class Codes: G01J 3/463 Colour matching
• CPC Class Codes: G01J 3/465 taking into account the colour perception of the eye; using tristimulus detection
• CPC Class Codes: G01J 3/505 measuring the colour produced by lighting fixtures other than screens, monitors, displays or CRTs
• CPC Class Codes: G01J 3/51 using colour filters
• CPC Class Codes: G01J 3/524 Calibration of colorimeters
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 5/77 : Retouching; Inpainting; Scratch removal
• CPC Class Codes: G06T 7/90 : Determination of colour characteristics
• CPC Class Codes: G09G 2320/0276 : for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/043 : Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/0606 : Manual adjustment
• CPC Class Codes: G09G 2320/0626 : for control of overall brightness
• CPC Class Codes: G09G 2320/066 : for control of contrast
• CPC Class Codes: G09G 2320/0666 : for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0693 : Calibration of display systems
• CPC Class Codes: G09G 2320/08 : Arrangements within a display terminal for setting, manually or automatically, display parameters of the display terminal
• CPC Class Codes: G09G 5/02 : characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 1/6055 : using test pattern analysis
• CPC Class Codes: H04N 1/6058 : Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut
• CPC Class Codes: H04N 17/02 : for colour television signals
• CPC Class Codes: H04N 9/643 : Hue control means, e.g. flesh tone control
• CPC Class Codes: H04N 9/646 : for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters
• CPC Class Codes: H04N 9/69 : for modifying the colour signals by gamma correction controlling camera response for colour signals H04N23/83

Abstract

In the color imaging system, multiple rendering devices are provided at different nodes along a network. Each rendering device has a color measurement instrument for calibrating the color presented by the rendering device. A rendering device may represent a color display in which a member surrounds the outer periphery of the screen of the display and a color measuring instrument is coupled to the first member. The color measuring instrument includes a sensor spaced from the screen at an angle with respect to the screen for receiving light from an area of the screen. A rendering device may be a printer in which the measuring of color samples on a sheet rendered by the printer is provided by a sensor coupled to a transport mechanism which moves the sensor and sheet relative to each other, where the sensor provides light from the sample to a spectrograph. The color measuring instruments provide for non-contact measurements of color samples either displayed on a color display, or printed on a sheet, and are self-calibrating by the use of calibration references in the instrument.

Claims

1-33. -33. (canceled)

34. An apparatus for measuring color rendered by a printer comprising:

means for transporting a sheet rendered from the printer having color samples;

at least one optical sensor coupled to said transporting means which is directed to said sheet to measure the color of the color sample; and

said sensor comprising at least one fiber optic probe and a spectrograph coupled to said fiber optic probe, and said spectrograph comprises means for automatically obtaining references for calibration of the spectrograph.

35. The apparatus according to claim 34 wherein said transporting means enables said sensor and the sample to move relative to each other to scan the sample.

36. The apparatus according to claim 34 further comprising an illuminator for supplying light to said sample.

37. The apparatus according to claim 36 where said illuminator and said sensor are disposed adjacent to the surface of said sample without contacting said sample at about 45 degrees to each other.

38. The apparatus according to claim 36 wherein said illuminator has a first polarizer for polarizing light from said illuminator, and said sensor has a second polarizer which cross polarizes the light received from said sample.

39. A system for controlling color reproduction comprising:

a network having one or more nodes;

one of said nodes having a computer system having a database;

means for communicating between others of said nodes and said one of said nodes; and

said other of said nodes each having at least one rendering device, wherein said database stores data for calibrating the rendering device at each of said nodes.

40. The system according to claim 39 wherein said data represents one or more color profiles.

41. The system according to claim 39 further comprising means for virtual proofing at the rendering device of said other of said nodes.

42. A system for capturing spectral images of an object comprising:

means for capturing spectral data characterizing the object;

means for capturing one or more images of the object, wherein at least one of said images represents approximately photopic sensitivity and is capable of having spatial resolution higher than the spatial resolution of said spectral data; and

storage for multi-resolution image data representing said spectral data and said images.

43. A method for capturing spectral images of an object comprising the steps of:

capturing spectral data characterizing an object;

capturing one or more images of said object, wherein at least one of said images represents approximately photopic sensitivity and is capable of having spatial resolution higher than the spatial resolution of said spectral data; and

storing multi-resolution image data representing said spectral data and said images.

44. An imaging device comprising:

optics for capturing spectral data characterizing an object;

a camera for capturing one or more images of said object, wherein at least one of said images represents approximately photopic sensitivity and is capable of having spatial resolution higher than the spatial resolution of said spectral data; and

storage for multi-resolution image data representing said spectral data and said images.

45. The device according to claim 44 wherein said optics comprise a spectrograph.

46. The device according to claim 44 wherein said multi-resolution image data are stored hierarchically in said storage.

47. The device according to claim 44 further comprising a module to translate said camera spatially with respect to said object.

48. The device according to claim 44 wherein said device is associated with a micro-processor capable of interpreting the colors of said object independently of the source illuminating said object to enable said object to be viewed as it would appear under one or more different illumination conditions.

49. A method for autocalibration and verification operable in a digital processor coupled to a video display to insure that calibration parameters required by a color translator are consistent with the state of said display, said method comprising the steps of:

estimating dark current in a sensor positioned to receive light emitted or reflected from the screen of said video display in order to enable correct readings of said sensor;

making a measurement of said emitted or reflected light when the input to each color channel of said video display is set to zero; and

checking whether said measurement is within tolerance.

50. The method according to claim 49 further comprising the steps of:

alerting a user of said display when said measurement is outside said tolerance;

modifying said color translator in accord with said measurement when said measurement is outside said tolerance and repeating said making and checking steps until said measurement is within tolerance;

inputting a series of digital levels to each color channel of said video display and measuring input-output relationship given by light output in response to input levels;

comparing said input-output relationship in accordance with a target relationship by said color translator;

adjusting said color channels until said input-output relationship is at or near to that required by said color translator;

measuring the relative activity in said color channels at highlight and shadow;

comparing said relative activity in accordance with a target relative activity for said color translator;

modifying the balance among said color channels when said measured relative activity in not at or near said target relative activity; and

repeating said measuring, modifying, and comparing steps until said measured relative activity in at or near said target relative activity.

51. An apparatus for maintaining colorimetric calibration and regional homogeneity of color rendering, said apparatus comprising:

a sensor capable of readings from any region of a display surface without requiring placement of said sensor by an operator at each said region, wherein said sensor and associated optics are non-contact with said surface;

a control unit comprising circuitry capable of processing said readings to produce digital data representative of the colors of the regions of said display surface;

a rendering device capable of rendering known digital image data upon said display surface; and

a computer capable of sending said known digital image data to said rendering device, receiving said digital data from said control unit, and transforming said digital data to device-independent color units to enable correction of color rendering to within a tolerance expressible in standard units, said correction comprising at least making said rendering regionally homogeneous on said display surface.

52. An instrument capable of measuring emitted, transmitted or reflected light from an object comprising:

an assembly having an aperture for admitting light from said object, said assembly comprising at least one of an enclosure and at least one fiber optic;

an optical module comprising one of a spectrograph, a set of calorimetric filters or a luminance filter capable of rejecting infrared light wherein said optical module modifies said light from said object;

a first sensor configuration, associated with said optical module, for converting said modified light into electrical signals, said optical module and said first sensor configuration being connectable with said assembly at least one of optically and mechanically;

a control unit comprising a processor capable of operating said instrument responsive to application software;

an interface through which said processor is capable of receiving commands of said application software from a computer and of transmitting data produced by said instrument by measuring said light from said object to said computer, said interface being one of a network connection, or a direct, serial link to said computer; and

a second sensor configuration capable of indicating the effects of temperature on signals generated in darkness.

53. A light measuring instrument comprising:

a measurement module for receiving light and converting said light into electrical signals;

a control unit comprising a processor capable of operating said measurement module and processing said electrical signals;

at least one device enabling a user to interface with said control unit;

an interface through which said control unit communicates with a computer capable of communication over a network; and

memory accessible by said control unit for storing files comprising at least measurement data, transforming procedures, and user preferences for operation of said control unit, wherein at least part of said files are shareable in a network.