WO2004030378A2 - Image quality indicator - Google Patents

Image quality indicator Download PDF

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Publication number
WO2004030378A2
WO2004030378A2 PCT/DK2003/000615 DK0300615W WO2004030378A2 WO 2004030378 A2 WO2004030378 A2 WO 2004030378A2 DK 0300615 W DK0300615 W DK 0300615W WO 2004030378 A2 WO2004030378 A2 WO 2004030378A2
Authority
WO
WIPO (PCT)
Prior art keywords
image
image processor
quality parameter
processor according
camera
Prior art date
Application number
PCT/DK2003/000615
Other languages
French (fr)
Other versions
WO2004030378A3 (en
Inventor
Anders Poulsen
Original Assignee
Hasselblad A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hasselblad A/S filed Critical Hasselblad A/S
Priority to AU2003266207A priority Critical patent/AU2003266207A1/en
Publication of WO2004030378A2 publication Critical patent/WO2004030378A2/en
Publication of WO2004030378A3 publication Critical patent/WO2004030378A3/en
Priority to US11/087,722 priority patent/US20050219400A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N17/00—Diagnosis, testing or measuring for television systems or their details
    • H04N17/002—Diagnosis, testing or measuring for television systems or their details for television cameras

Definitions

  • the present invention relates to electronic cameras comprising solid state imaging devices, such as CCDs. More particularly, the present invention relates to circuits and techniques for indication of quality of recorded images.
  • US 5,040,072 discloses an electronic still camera employing a CCD, wherein an automatic exposure control and an automatic focusing control are performed by utilizing an image signal derived from the CCD. Exposure control parameters and focusing parameters are automatically determined based on luminance in the image recorded by the CCD.
  • the CCD is an array of a large number of light sensitive detectors connected to each other as an analogue shift register.
  • a charge is formed that is proportional to the light energy incident on the detector during an integration period.
  • the analogue charge of each detector is shifted serially out of the CCD and is typically converted to a digital value whereby a digital representation of the recorded image is formed.
  • Each pixel value of the digital image is equal to the digitised charge of the corresponding CCD detector.
  • the image is divided into a large number of segments, denoted pixels, with allocated digital values denoted pixel values.
  • a grey tone image may be represented digitally by pixels with one respective pixel value representing the grey tone of the corresponding pixel.
  • a colour image may be represented by pixels having three respective pixel values, one for each of the colours red, green, and blue.
  • exposure is to be understood in a broad sense as the time period during which an energy sensor is actually sensing the energy. For example, a photographic film is exposed to light whenever light is incident upon it, while a CCD is exposed to light when the pixel elements of the CCD are allowed to integrate light incident upon them.
  • a colour filter mask may be overlaid the CCD array whereby each light sensitive pixel element in the CCD-array is covered with a colour filter for passing radiation within a specific spectral range corresponding to a specific primary colour, typically red, green and blue.
  • the colour filter mask allows a colour image to be recorded in a single exposure at the expense of resolution.
  • a solid state imaging device such as a video camera, a still camera, etc
  • an image processor for use with an electronic camera comprising an object lens for focusing an image of an object onto an image plane, and a solid state imaging device positioned at the image plane for conversion of the image into electrical signals.
  • the image processor is adapted for processing the electrical signals into a quality parameter and for controlling signalling of the quality parameter to an operator of the electronic camera.
  • the image processor may be adapted for calculation of one or more quality parameters, such as luminance, brightness, contrast, colour balance, white balance, focus, etc.
  • the camera may further comprise automatic adjustment means for adjustment of the camera in response to the calculated quality parameters so that a new image recording may be performed with optimum settings of the camera.
  • the camera objective may be focused based on the calculated focus parameter, or a diaphragm may be adjusted in response to the calculated brightness.
  • one or more of the calculated parameters may be displayed to the operator of the camera, e.g. in the viewer of the camera. Preferably, however, a warning is displayed when at least one of the quality parameters is outside a predetermined desirable range.
  • the camera comprises a sound reproducing element that is controlled by the image processor for emission of an audible sound when at least one of the quality parameters is outside a predetermined desirable range.
  • the audible sound may, e.g., be a single distinct sound ("bip") of a specific frequency, a modulated sound, a swept sound, a series of distinct sounds of a specific frequency or of different frequencies, such as a tune, etc, as is well-known in the art of mobile telephones.
  • a plurality of distinguishable sounds may be related to specific respective qualities of the image. For example, a sound swept from a low frequency to a high frequency may signal that the recorded image is over-exposed while a sound swept from a high frequency to a low frequency may signal that the recorded image is under-exposed.
  • the image processor may be adapted for calculation of at least one histogram of parameters of a selected colour space so that the quality parameter may be calculated based on the at least one histogram.
  • the camera may further comprise a selector for user selection of a part of the image, and wherein the quality parameter is calculated based solely on electrical signals from pixels within the selected part of the image.
  • the operator of the camera may select a part of the viewing field to form basis for the quality parameter determination, e.g. a central part of the viewing field.
  • Fig. 1 is a blocked schematic of an electronic camera according to the present invention
  • Fig. 2 is a grey-scale image
  • Fig. 3 is a histogram of the grey-scale image of Fig. 2.
  • Fig. 1 is a blocked schematic of an electronic camera 10 according to the present invention.
  • a movable object lens 12 focuses an image of an object (not shown) in co-operation with second lens 14 onto an image plane 16 which coincides with the light sensitive surfaces of the array of light sensitive sensors of the CCD 18.
  • the image recording of the CCD 18 is controlled by a CCD driver 20 that enables and disables integration of light by the CCD light sensors, and also controls shifting of the accumulated charges out of the CCD 18 thereby forming the electrical signals.
  • the electrical signals are received by the image processor 22 that composes a digital image based on the electrical signals and also calculates quality parameters of the image.
  • a lens drive motor 24 is controlled to move the objective lens 12 to focus the image.
  • a diaphragm drive motor 26 is controlled to adjust the aperture of the diaphragm, and the integration time period of the CCD is controlled for optimum exposure of the next image.
  • a warning signal is displayed in a field 28 of the viewer when one of the calculated quality parameters are outside predetermined respective desired ranges.
  • the camera further has a sound reproducing element 30 that is controlled by the image processor 22 for emission of an audible sound when at least one of the quality parameters is outside a predetermined desirable range.
  • the quality factors may be calculated from a histogram of a recorded image as illustrate in Figs. 2 and 3. For example, in an over-exposed image, the histogram-distribution will move to the right and pixels will be missing at the low end of the histogram, and in an under-exposed image, the histogram- distribution will move to the left and pixels will be missing at the high end of the histogram.

Abstract

The present invention relates to an electronic camera (10) comprising a solid state imaging device, such as a CCD (18). More particularly, the present invention provides an image processor (22) that is adapted to calculate a quality parameter and for controlling signalling of the quality parameter to an operator of the electronic camera. The quality of the recorded image may be based on a histogram of image pixel values.

Description

IMAGE QUALITY INDICATOR
FIELD OF THE INVENTION
The present invention relates to electronic cameras comprising solid state imaging devices, such as CCDs. More particularly, the present invention relates to circuits and techniques for indication of quality of recorded images.
BACKGROUND OF THE INVENTION
US 5,040,072 discloses an electronic still camera employing a CCD, wherein an automatic exposure control and an automatic focusing control are performed by utilizing an image signal derived from the CCD. Exposure control parameters and focusing parameters are automatically determined based on luminance in the image recorded by the CCD.
The CCD is an array of a large number of light sensitive detectors connected to each other as an analogue shift register. In each detector of the CCD, a charge is formed that is proportional to the light energy incident on the detector during an integration period. The analogue charge of each detector is shifted serially out of the CCD and is typically converted to a digital value whereby a digital representation of the recorded image is formed. Each pixel value of the digital image is equal to the digitised charge of the corresponding CCD detector.
Thus, the image is divided into a large number of segments, denoted pixels, with allocated digital values denoted pixel values. For example, a grey tone image may be represented digitally by pixels with one respective pixel value representing the grey tone of the corresponding pixel. Similarly, a colour image may be represented by pixels having three respective pixel values, one for each of the colours red, green, and blue. In the present context, the term exposure is to be understood in a broad sense as the time period during which an energy sensor is actually sensing the energy. For example, a photographic film is exposed to light whenever light is incident upon it, while a CCD is exposed to light when the pixel elements of the CCD are allowed to integrate light incident upon them. A colour filter mask may be overlaid the CCD array whereby each light sensitive pixel element in the CCD-array is covered with a colour filter for passing radiation within a specific spectral range corresponding to a specific primary colour, typically red, green and blue. The colour filter mask allows a colour image to be recorded in a single exposure at the expense of resolution.
It is well-known in the art to automatically adjust focus and exposure of an electronic camera in order to record an image with optimum settings. However, the photographer is left without an indication of the quality of the image having been recorded.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image processor for use with an electronic camera with a solid state imaging device, such as a video camera, a still camera, etc, providing an indication of the quality of a recorded image to the photographer.
According to the present invention, the above-mentioned and other objects are fulfilled by an image processor for use with an electronic camera comprising an object lens for focusing an image of an object onto an image plane, and a solid state imaging device positioned at the image plane for conversion of the image into electrical signals. The image processor is adapted for processing the electrical signals into a quality parameter and for controlling signalling of the quality parameter to an operator of the electronic camera.
The image processor may be adapted for calculation of one or more quality parameters, such as luminance, brightness, contrast, colour balance, white balance, focus, etc.
The camera may further comprise automatic adjustment means for adjustment of the camera in response to the calculated quality parameters so that a new image recording may be performed with optimum settings of the camera. For example, the camera objective may be focused based on the calculated focus parameter, or a diaphragm may be adjusted in response to the calculated brightness.
Further, one or more of the calculated parameters may be displayed to the operator of the camera, e.g. in the viewer of the camera. Preferably, however, a warning is displayed when at least one of the quality parameters is outside a predetermined desirable range.
In a preferred embodiment of the present invention, the camera comprises a sound reproducing element that is controlled by the image processor for emission of an audible sound when at least one of the quality parameters is outside a predetermined desirable range. The audible sound may, e.g., be a single distinct sound ("bip") of a specific frequency, a modulated sound, a swept sound, a series of distinct sounds of a specific frequency or of different frequencies, such as a tune, etc, as is well-known in the art of mobile telephones.
A plurality of distinguishable sounds may be related to specific respective qualities of the image. For example, a sound swept from a low frequency to a high frequency may signal that the recorded image is over-exposed while a sound swept from a high frequency to a low frequency may signal that the recorded image is under-exposed. The image processor may be adapted for calculation of at least one histogram of parameters of a selected colour space so that the quality parameter may be calculated based on the at least one histogram.
The camera may further comprise a selector for user selection of a part of the image, and wherein the quality parameter is calculated based solely on electrical signals from pixels within the selected part of the image. Hereby, the operator of the camera may select a part of the viewing field to form basis for the quality parameter determination, e.g. a central part of the viewing field.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be described in greater detail in the following, by way of example only and with reference to the attached drawings in which:
Fig. 1 is a blocked schematic of an electronic camera according to the present invention,
Fig. 2 is a grey-scale image, and
Fig. 3 is a histogram of the grey-scale image of Fig. 2. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The operational principles of the invention will now be explained with reference to Fig. 1. Fig. 1 is a blocked schematic of an electronic camera 10 according to the present invention. A movable object lens 12 focuses an image of an object (not shown) in co-operation with second lens 14 onto an image plane 16 which coincides with the light sensitive surfaces of the array of light sensitive sensors of the CCD 18. The image recording of the CCD 18 is controlled by a CCD driver 20 that enables and disables integration of light by the CCD light sensors, and also controls shifting of the accumulated charges out of the CCD 18 thereby forming the electrical signals. The electrical signals are received by the image processor 22 that composes a digital image based on the electrical signals and also calculates quality parameters of the image. Based on a focus parameter value, a lens drive motor 24 is controlled to move the objective lens 12 to focus the image. Based on a brightness parameter value, a diaphragm drive motor 26 is controlled to adjust the aperture of the diaphragm, and the integration time period of the CCD is controlled for optimum exposure of the next image. A warning signal is displayed in a field 28 of the viewer when one of the calculated quality parameters are outside predetermined respective desired ranges. The camera further has a sound reproducing element 30 that is controlled by the image processor 22 for emission of an audible sound when at least one of the quality parameters is outside a predetermined desirable range.
As already mentioned, the quality factors may be calculated from a histogram of a recorded image as illustrate in Figs. 2 and 3. For example, in an over-exposed image, the histogram-distribution will move to the right and pixels will be missing at the low end of the histogram, and in an under-exposed image, the histogram- distribution will move to the left and pixels will be missing at the high end of the histogram.

Claims

1. An image processor for use with an electronic camera comprising an object lens for focusing an image of an object onto an image plane, and a solid state imaging device positioned at the image plane for conversion of the image into electrical signals, the image processor being adapted for processing the electrical signals into a quality parameter and for controlling signalling of the quality parameter to an operator of the electronic camera.
2. An image processor according to claim 1, wherein the quality parameter is based on luminance values from the pixels.
3. An image processor according to claim 1 or 2, wherein the image processor is adapted for calculation of at least one histogram of parameters of a selected colour space and wherein the quality parameter is calculated based on the at least one histogram.
4. An image processor according to any of the preceding claims, further comprising a selector for user selection of a part of the image, and wherein the quality parameter is calculated based solely on electrical signals from pixels within the selected part of the image.
5. An image processor according to any of the preceding claims, further being adapted to control a sound reproducing element for emission of a warning sound when the quality parameter is below a predetermined threshold.
6. An image processor according to any of the preceding claims, further being adapted to control a visual display element for displaying a warning when the quality parameter is below a predetermined threshold.
7. An image processor according to claim 6, wherein the visual display element resides in the viewer of the camera.
PCT/DK2003/000615 2002-09-24 2003-09-22 Image quality indicator WO2004030378A2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU2003266207A AU2003266207A1 (en) 2002-09-24 2003-09-22 Image quality indicator
US11/087,722 US20050219400A1 (en) 2002-09-24 2005-03-24 Image quality indicator

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA200201409 2002-09-24
DKPA200201419 2002-09-24

Related Child Applications (1)

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WO2004030378A2 true WO2004030378A2 (en) 2004-04-08
WO2004030378A3 WO2004030378A3 (en) 2004-04-29

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006030068A1 (en) * 2004-09-14 2006-03-23 Nokia Corporation Method, device and software for improving the quality of a video recording
WO2006038092A1 (en) * 2004-10-05 2006-04-13 Nokia Corporation System and method for checking framing and sharpness of a digital image
EP1739982A1 (en) * 2005-06-30 2007-01-03 Hasselblad A/S An electronic camera with classification of images according to image quality
US7860332B2 (en) * 2005-01-07 2010-12-28 Hewlett-Packard Development Company, L.P. Method and system for determining an indication of focus of an image
US9338348B2 (en) 2012-10-23 2016-05-10 Snapaid Ltd. Real time assessment of picture quality

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JP2003046918A (en) * 2001-07-27 2003-02-14 Canon Inc Imaging apparatus and method therefor, computer- readable record medium, and computer program
EP1322109A2 (en) * 2001-12-19 2003-06-25 Nokia Corporation Digital camera
US20030151674A1 (en) * 2002-02-12 2003-08-14 Qian Lin Method and system for assessing the photo quality of a captured image in a digital still camera

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JP3551264B2 (en) * 1993-10-22 2004-08-04 東急建設株式会社 Method of creating evaluation image of plant vitality fluctuation
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JP2003046918A (en) * 2001-07-27 2003-02-14 Canon Inc Imaging apparatus and method therefor, computer- readable record medium, and computer program
EP1322109A2 (en) * 2001-12-19 2003-06-25 Nokia Corporation Digital camera
US20030151674A1 (en) * 2002-02-12 2003-08-14 Qian Lin Method and system for assessing the photo quality of a captured image in a digital still camera

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006030068A1 (en) * 2004-09-14 2006-03-23 Nokia Corporation Method, device and software for improving the quality of a video recording
WO2006038092A1 (en) * 2004-10-05 2006-04-13 Nokia Corporation System and method for checking framing and sharpness of a digital image
US7860332B2 (en) * 2005-01-07 2010-12-28 Hewlett-Packard Development Company, L.P. Method and system for determining an indication of focus of an image
EP1739982A1 (en) * 2005-06-30 2007-01-03 Hasselblad A/S An electronic camera with classification of images according to image quality
US9338348B2 (en) 2012-10-23 2016-05-10 Snapaid Ltd. Real time assessment of picture quality
US9661226B2 (en) 2012-10-23 2017-05-23 Snapaid Ltd. Real time assessment of picture quality
US10009537B2 (en) 2012-10-23 2018-06-26 Snapaid Ltd. Real time assessment of picture quality
US10659682B2 (en) 2012-10-23 2020-05-19 Snapaid Ltd. Real time assessment of picture quality
US10944901B2 (en) 2012-10-23 2021-03-09 Snapaid Ltd. Real time assessment of picture quality
US11252325B2 (en) 2012-10-23 2022-02-15 Snapaid Ltd. Real time assessment of picture quality
US11671702B2 (en) 2012-10-23 2023-06-06 Snapaid Ltd. Real time assessment of picture quality

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Publication number Publication date
WO2004030378A3 (en) 2004-04-29
AU2003266207A1 (en) 2004-04-19

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