Method of controlling an Action, Such as a Sharpness Modification, Using a Colour Digital Image

• US 20080158377A1
• Filed: 03/06/2006
• Published: 07/03/2008
• Est. Priority Date: 03/07/2005
• Status: Active Grant

• Current Assignee: Lens Correction Technologies Corporation
• Original Assignee: DXO Labs
• Inventors: Chanas, Laurent, Guichard, Frederic, Liege, Bruno, Tarchouna, Imene, Meniere, Jerome
• Granted Patent: US 7,920,172 B2
• Time in Patent Office: Days
• US Class Current: 348/222.1
• CPC Class Codes: H04N 23/64 Computer-aided capture of images, e.g. transfer from script file into camera, check of taken image quality, advice or proposal for image composition or decision on when to take image
• CPC Class Codes: H04N 23/959 by adjusting depth of field during image capture, e.g. maximising or setting range based on scene characteristics
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 25/615 involving a transfer function modelling the optical system, e.g. optical transfer function [OTF], phase transfer function [PhTF] or modulation transfer function [MTF]
• CPC Class Codes: H04N 25/6153 for colour signals

Abstract

The invention concerns a method for activating a function by using a measurement taken from at least one digital image (10) having at least two colours (195, 196) and originating from an image-capturing apparatus.

According to such method:

• • the relative sharpness is measured (190) between at least two colours in at least one region R of the image, and
  • at least one action is controlled (191) depending on the measured relative sharpness.

Claims

1. A method for activating a function by using a measurement taken from at least one digital image having at least two colours and originating from an image-capturing apparatus, wherein:

the relative sharpness is measured between at least two colours on at least one region R of the image, and

at least one function is activated depending on the measured relative sharpness.

2. A method according to claim 1 wherein the function activated is included in the group comprising:

a determination of the distance between the capturing apparatus and at least one object imaged by the digital image, and/or the determination of the relative distance between two imaged objects,

an action depending on the said distance and/or the said relative distance,

a process on at least one zone Z′

of the digital image and/or of another digital image,

a servo-control of the capturing apparatus and/or a servo-control of another apparatus,

the provision of an indication and/or alarm and/or alert signal to a user,

the detection of a part of the image,

an alteration of a colour sharpness,

a determination of the position and/or of the movement of the capturing apparatus,

the determination of a subject'"'"'s position within the image,

an alteration of at least one image specification,

an alteration of all or part of the image,

the determination of a zone of interest inside the image, notably in order to provide a servo-control signal,

the alteration of the resolution for all or part of the image,

the provision of data relating to the image,

the provision of data to a sound-capturing device,

the parametering of a compression,

at least one adjustment for the capturing apparatus.

3. A method according to claims 1 or 2 wherein the function activated includes a process on at least one zone Z′

of the digital image and/or of another digital image, and wherein the zone Z′

constitutes all or part of the digital image region, and/or the whole digital image, and/or a separate zone from the digital image region, and/or another digital image, and/or another whole digital image.

4. A method according to claim 3 wherein the zone Z′

, for which a process is activated, comprises at least one pixel of an image and wherein the region R comprises a pre-determined vicinity of the corresponding pixel in the digital image.

5. A method according to claim 4, wherein the process is applied to all the pixels of an image.

6. A method according to one of the claims 3 to 5 wherein the process on at least the zone Z′

includes alteration of at least one specification contained in the group comprising;

sharpness, contrast, luminosity, detail, colour, the type of compression, the rate of compression, the image contents, the resolution.

7. A method according to one of the claims 3 to 6 wherein the process includes an alteration of the sharpness of each pixel in the zone Z′

by way of a filter mixing the values attached to the pixel or pixels within a pre-determined vicinity for each pixel, the parameters of the filter depending upon the measured relative sharpness.

8. A method according to one of the claims 3 to 7 wherein the zone Z′

is determined by using the measured relative sharpness.

9. A method according to one of the claims 3 to 8 wherein the zone Z′

constitutes a background for an image, notably destined for remote transmission, especially through a system of visio or video-conferencing.

10. A method according to claims 3 to 9 wherein the process includes the provision of data depending on the distance between the imaged object and the capturing apparatus for all or part of the pixels of the zone Z′

, and wherein is activated the storage and/or the transmission and/or the use of such data depending on the distance, the stored data notably being saved in a data-processing file, namely in an image file.

11. A method according to one of the preceding claims wherein the function activated includes a servo-control of the capturing apparatus, such as a servo-control for focussing and/or of exposure, and/or of flash, and/or for image-framing, and/or for white-balancing, and/or for image-stabilising, and/or a servo-control of another apparatus or device linked to the capturing apparatus, such as the guiding of a robot.

12. A method according to one of the preceding claims wherein the function activated includes a provision of a signal, such as an indication signal of the main focal point of the digital image and/or of a focussing zone and/or of the distance of at least one part of the imaged scene, to the capturing apparatus.

13. A method according to one of the preceding claims wherein the function activated depends upon at least one specification of the capturing apparatus during picture-taking, namely the focal length, the aperture, the distance for focussing, the exposure parameters, the white-balance parameters, the resolution, the compression, or an adjustment made by the user.

14. A method according to one of the preceding claims wherein the digital image constitutes a raw image stemming from the sensor of the capturing apparatus.

15. A method according to one of the preceding claims wherein the measurement is made inside the capturing apparatus and/or the function activated is made inside the capturing apparatus.

16. A method according to one of the preceding claims wherein the measurement is taken beyond the capturing apparatus, for example on a computer after transfer of the image, and/or wherein a function is activated beyond the capturing apparatus.

17. A method according to one of the preceding claims wherein the function activated comprises a detection and/or recognition activation of a part of the image, such as detection and/or recognition of the face.

18. A method according to one of the preceding claims wherein the measurement comprises a measurement of relative sharpness between a first colour and at least a second colour, referred to as the other colour, and wherein the activation comprises alteration of the sharpness of the other colour depending on the sharpness of the first colour.

19. A method according to claim 18 wherein the sharpness alteration of the other colour is embodied using a calculation of the type CA=CN+F(CO−

CN), where CA represents the other improved colour, CO represents the other colour prior to processing, CN represents the first colour and F represents a filter, namely a no-go filter.

20. A method according to one of the claims 18 to 22 wherein alteration of the sharpness of the other colour is an improvement of the sharpness, the first colour being referred to as the “

sharp colour”

.

21. A method according to claim 20 further comprising the step of decomposing the digital image into regions (11.1, 11.2), the sharp colour being selected one for each region.

22. A method according to claims 20 or 21, the said capturing apparatus comprising a macro mode, a method wherein the sharp colour is selected depending on activation of the macro mode.

23. A method according to claims 18 or 19 wherein the sharpness of at least one colour within at least one image zone is reduced.

24. A method according to one of the preceding claims, for which the said digital image stems from a capturing apparatus comprising a lens, the said method further including the step to select a lens from among a series of pre-determined lenses, the said lens representing specifications such that the images of an object with at least two distinct pre-determined distances represent distinct colours of sharpness, thus improving the depth of field and reducing the cost of the lens.

25. A method according to one of the preceding claims wherein the function activated comprises a measurement of the position and/or movement of the capturing apparatus.

26. A method according to one of the preceding claims wherein the function activated involves determination of the position of the main subject or subjects in the image.

27. A method according to claim 26 wherein the function activated further involves the automatic framing, namely the centering, zooming or reframing of the digital image, and/or of another image, in relation to the main subject of the digital image.

28. A method according to one of the preceding claims wherein the function activated comprises the application of a process depending on the relative sharpness and on the user'"'"'s choice.

29. A method according to one of the preceding claims wherein the function activated comprises alteration of the contrast and/or of the brightness and/or of the colour and/or of the sharpness of an image, depending on the variation of the relative sharpness within the image.

30. A method according to one of the preceding claims wherein the function activated comprises provision of the position of at least one zone of interest for consideration to a servo-control of exposure and/or of white balance and/or of focussing, such zone of interest being determined by comparing at least two relative sharpness measurements.

31. A method according to one of the preceding claims wherein the function activated comprises provision of a signal to the user, indicating that the image is taken too close-up to be sharp.

32. A method according to one of the preceding claims wherein the function activated comprises alteration of an image resolution depending on the relative sharpness.

33. A method according to one of the preceding claims wherein the function activated comprises the provision of a signal used for an automatic indexing of the digital image.

34. A method according to one of the preceding claims wherein the function activated comprises provision of remote or directional data, in relation to the capturing apparatus, of a subject or an object of the digital image, to a sound-capturing device.

35. A method according to one of the preceding claims wherein the function activated includes the parametering of increased compression for the background, and of reduced compression for the main subject or subjects, such main subject or subjects being determined as an image zone complying with the criteria based upon the measured relative sharpness.

36. A method according to one of the preceding claims wherein the apparatus comprises a sensor having pixels equipped with coloured filters of at least two types, the said filters being selected so that their spectral responses entail little overlapping.

37. A method according to one of the preceding claims wherein the apparatus comprises a sensor having pixels mainly serving to generate the image, and other pixels mainly serving to measure the relative sharpness.

38. A method according to claim 37 wherein the pixels of the sensor, mainly serving to measure the relative sharpness, have a spectral response within a spectral band which entails little overlapping with the spectral band of the sensor'"'"'s pixels, mainly serving to generate the image.

39. A method according to claims 37 or 38 wherein the pixels of the sensor, mainly serving to generate an image, have a spectral response that is mainly within the field visible to the human eye, and wherein the other pixels have a spectral response, mainly beyond the field visible to the human eye.

40. A method according to one of the preceding claims in which the capturing apparatus includes a sensor comprising spectral-response pixels, mainly within the field visible to the human eye, and additional pixels having a spectral response, mainly beyond the spectre visible to the human eye, and where the sharpness of the part of the image stemming from these additional pixels exceeds, within at least one range of distances between the capturing apparatus and the imaged scene, the sharpness of the part of the image supplied by the response pixels, mainly within the field visible to the human eye.

41. A method according to one of the preceding claims wherein the apparatus is equipped with a lens lacking a mobile or flexible element for focussing.

42. A method according to one of the preceding claims wherein the apparatus is equipped with a lens having a variable focal length with no mobile or flexible element for focussing.

43. A method according to one of the preceding claims wherein the apparatus is equipped with a lens having a variable focal length with a single mobile or flexible optics group.

44. A method according to one of the preceding claims wherein the digital image stems from at least two sensors.

45. A method according to one of the preceding claims wherein the function activated comprises the addition of an object inside an image and/or the replacement of a part of an image depending on the measured relative sharpness on the digital image.

46. A method according to one of the preceding claims wherein the capturing apparatus capturing a sequence of images, the digital image being a part of the sequence, the action is performed on at least one other image of the sequence.

47. A method according to one of the preceding claims wherein the function activated alters at least one adjustment of the capturing apparatus, namely the focal length, the aperture, the distance for focussing.

48. A method according to one of the preceding claims wherein the function activated comprises the production of an altered raw image.

49. A method according to one of the preceding claims wherein the apparatus comprising a lens having longitudinal chromatic aberrations, such as for a given focus, aperture and focal distance, there exists at least one colour for which the distance involving the best sharpness is lower than

50. A method according to one of the preceding claims wherein the measurement of relative sharpness between two colours is made by comparing the results of a first measurement applied to the first colour and the results of a second measurement applied to a second colour, each measurement being such that it depends upon, on the one hand, the colour, and upon the contents of the digital image on the other, the comparison being such that it is removed from the digital image contents.

51. A method according to one of the preceding claims, the said digital image stemming from a capturing apparatus comprising a lens, the said method further comprising the step to design a lens representing specifications such that the images of an object with at least two pre-determined distances represent distinct sharpness colours:

in order that the depth of field and/or the aperture and/or every other optical specification is improved, and/or that the cost of the optics is reduced.

52. An embodiment for an image-capturing and/or reproducing apparatus (20) comprising an optical system (22, 22′

) for capturing and/or reproducing images, an image sensor (24) and/or generator (24′

) and/or a servo-control system (26), the image being processed, in view of its improvement, by digital image-processing means (28, 28′

),

the method being such that the user determines or selects the optical system and/or the sensor and/or the image generator and/or the servo-control system parameters, using the capacity to process images via digital means, and further determines or selects improvement of a colour sharpness depending on another colour in accordance with a method complying with one of the preceding claims,

in order to minimise the embodiment costs and/or to optimise the performances of the image-capturing and/or reproducing apparatus.

53. Using the method according to one of the claims 1 to 52 inside an image-capturing apparatus.

54. Using the method according to one of the claims 1 to 51 inside a digital image-processing device.

55. A method for improving the sharpness of at least one colour of a digital image, notably stemming from an image-capturing device, comprising the steps of

selecting from among the colours at least one colour referred to as “

sharp colour”

,

reflecting the sharpness of the sharp colour onto at least one other improved colour,

so that the improved colour represents increased sharpness.

56. A method according to claim 55, the method further comprising the step of decomposing the digital image into regions (11.1, 11.2), the said sharp colour being selected for each region.

57. A method according to claim 56, the said digital image stemming from a capturing apparatus, the said method further comprising the step of determining the distance between the capturing apparatus and at least one object of the captured scene by using the sharpness of at least two colours in an image region of the said object.

58. A method according to claim 57, the said method further comprising the step to reduce the sharpness of at least one colour within at least one image region.

59. A method according to claims 57 or 58, the said method further comprising the step of determining a servo-control instruction for the said capturing apparatus by using the sharpness of at least two colours in order that focussing is achieved in fewer steps and is accelerated.

60. A method according to one of the claims 55 to 59, the said sharp colour selection being that of choosing the sharpest colour according to a pre-determined rule.

61. A method according to one of the claims 55 to 59, the said “

sharp colour”

selection being pre-determined.

62. A method according to one of the claims 55 to 61, the said digital image stemming from a capturing apparatus, the said sharp colour selection depending on the distance between the capturing apparatus and at least one object of the captured scene in order to obtain the said digital image.

63. A method according to claims 55 or 62, the said image apparatus comprising a macro mode, the said sharp colour selection depending upon activation of the macro mode.

64. A method according to one of the claims 55 to 63, the said digital image stemming from a capturing apparatus comprising a lens, the said method further comprising the step to select a lens from among a series of pre-determined lenses, the said lens representing specifications such that the images of an object having at least two pre-determined distances represent distinct sharp colours, thus improving the depth of field and/or reducing the cost of the lens.

65. A method according to one of the claims 55 to 64, wherein repercussion of the sharpness of the sharp colour on at least one other improved colour is embodied by using a calculation of the type CA=CN+F(CO−

CN), where CA represents the improved colour, CO represents the improved colour prior to processing, CN represents the sharp colour and F represents a filter, namely a low-pass filter.

66. A method according to one of the claims 55 to 65, the said digital image stemming from a capturing apparatus comprising a lens, the said method further comprising the step to design a lens by taking account of the method according to the invention, the said lens representing specifications such that the images of an object with at least two pre-determined distances represent distinct sharp colours:

in order that the depth of field and/or the aperture and/or every other optical specification is improved and/or the cost of the optics is reduced.

in order that the mechanical focussing can be achieved by using fewer positions.

67. An embodiment for an image-capturing and/or reproducing apparatus (20) comprising an optical system (22, 22′

) for capturing and/or reproducing images, an image sensor (24) and/or generator (24′

) and/or a servo-control system (26), the image being processed, in view of its improvement, by digital image-processing means (28, 28′

),

the method being such that the user determines or selects the optical system and/or the sensor and/or the image generator and/or the servo-control system parameters, using the capacity to process images via digital means, and especially for improving the sharpness of a colour depending on the sharpness of another colour in accordance with a method complying with one of the claims 55 to 66,

in order to minimise the embodiment costs and/or to optimise the performances of the image-capturing and/or reproducing apparatus.

68. An image-capturing and/or reproducing apparatus using a colour-improvement method according to one of the claims 55 to 66 and/or obtained via an embodiment according to claim 67.

69. A digital image-processing device implementing a method according to claims 55 to 66.

70. A digital image obtained according to a method complying with one of the claims 55 to 66 or using an apparatus complying with claim 68.

71. A sensor for a digital image-capturing apparatus comprising pixels, mainly serving to generate the digital image, and other pixels, mainly serving to measure the relative sharpness between at least two colours on at least one region R of the image.

72. A sensor according to claim 71 wherein the pixels, mainly serving to measure the relative sharpness, have a spectral response within a spectral band which entails little overlapping with the spectral band of the pixels, mainly serving to generate the image.

73. A sensor according to claims 71 or 72 wherein the pixels, mainly serving to generate the image, have a spectral response, mainly within the field visible to the human eye, and the other pixels have a spectral response, mainly beyond the field visible to the human eye.

74. A capturing apparatus comprising a sensor according to one of the claims 71 to 73.

75. A digital image-capturing apparatus comprising a sensor representing, on the one hand, spectral response pixels, mainly within the field visible to the human eye, and additional pixels having a spectral response, mainly beyond the spectre visible to the human eye, on the other, the sharpness of the part of the image stemming from these additional pixels exceeding, within at least one range of distances between the capturing apparatus and the imaged scene, the sharpness of the part of the image provided by the pixels whose spectral response is mainly within the field visible to the human eye.

76. An apparatus according to claim 75 wherein the additional pixels have a spectral response mainly within the ultraviolet and/or infrared field.