Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/50—Constructional details
  • H04N23/54—Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/70—Circuitry for compensating brightness variation in the scene
  • H04N23/741—Circuitry for compensating brightness variation in the scene by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/45—Cameras or camera modules comprising electronic image sensors; Control thereof for generating image signals from two or more image sensors being of different type or operating in different modes, e.g. with a CMOS sensor for moving images in combination with a charge-coupled device [CCD] for still images
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/70—Circuitry for compensating brightness variation in the scene
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/95—Computational photography systems, e.g. light-field imaging systems
  • H04N23/951—Computational photography systems, e.g. light-field imaging systems by using two or more images to influence resolution, frame rate or aspect ratio
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/60—Control of cameras or camera modules
  • H04N23/63—Control of cameras or camera modules by using electronic viewfinders

Definitions

• the invention relates to electronic cameras, and particularly to methods and electronic camera apparatus for capturing multiple exposures.
• the invention has application in capturing high dynamic range images.
• High dynamic range (“HDR”) image formats permit recording contrast ratios that are significantly greater than those of conventional 8-bit image formats.
• some HDR formats use 16 or 32 bits per colour to represent different levels of brightness.
• One way to obtain image data for high dynamic range images is to acquire multiple images with conventional imaging equipment at different exposure levels. This technique is described, for example, in Debevec et al. Recovering High Dynamic Range Radiance Maps from Photographs, Proceedings of SIGGRAPH 97, Computer Graphics Proceedings, Annual Conference Series, pp. 369-378 (March 1997, Los Angeles, California), Addison Wesley, Edited by Turner Whitted. ISBN 0-89791-896-7, which is hereby incorporated herein by reference. [0005] A problem is that the multiple images need to be aligned with one another. This makes it necessary to use a tripod in most cases. Further, setting a camera to take multiple images appropriate for combination into an HDR image requires significant knowledge regarding the appropriate combination of exposures to use for each of the images.
• HDR images are becoming mainstream. There is a need for methods and apparatus for easily acquiring HDR images.
• This invention provides methods and apparatus for acquiring multiple exposures in electronic cameras.
• the methods and apparatus may be applied to acquiring images that can be combined to yield an HDR image.
• Apparatus according to some embodiments of the invention may comprise an electronic camera having multiple image sensors.
• One aspect of the invention provides an electronic camera comprising two or more image sensor arrays. At least one of the image sensor arrays has a high dynamic range.
• the camera also comprises a shutter for selectively allowing light to reach the two or more image sensor arrays, readout circuitry for selectively reading out pixel data from the image sensor arrays, and, a controller configured to control the shutter and the readout circuitry.
• the controller comprises a processor and a memory having computer-readable code embodied therein which, when executed by the processor, causes the controller to open the shutter for an image capture period to allow the two or more image sensor arrays to capture pixel data, and, read out pixel data from the two or more image sensor arrays.
• Another aspect of the invention provides a method for producing high dynamic range image data in an electronic camera comprising two or more image sensor arrays, at least one of the image sensor arrays having a high dynamic range.
• the method comprises allowing light to reach the two or more image sensor arrays for an image capture period, reading out pixel data captured by the two or more image sensor arrays during the image capture period, and, combining the pixel data read out from the two or more image sensor arrays to produce high dynamic range image data.
• Figure 1 shows a sensor layout for an interline transfer CCD
• Figure 2 is a block diagram of an electronic camera according to one embodiment of the invention
• Figure 3 is a flowchart illustrating the steps in a method according to another embodiment of the invention.
• One aspect of the invention provides an electronic camera configured to capture multiple exposures of a single image.
• the multiple exposures may be used to create a high dynamic range (HDR) image.
• HDR high dynamic range
• Methods for combining data from multiple exposures to yield a HDR image are known in the art. For example, some such methods are described in Mann, S. et al. Being 'undigitaV with digital cameras: Extending dynamic range by combining differently exposed pictures , In Proc. IS&T 46th Annual Conference (May, 1995) pp. 422-428 which is hereby incorporated herein by reference and in the Debevec et al. article referred to above.
• Electronic cameras typically have a shutter which can be opened to selectively allow light to reach a light sensitive chip or closed to block light from reaching the chip.
• a lens projects an image onto the chip.
• the shutter may comprise a mechanical shutter, for example.
• the chip measures light intensity at a number of pixel locations. Values representing the intensity at each of the pixels can be read out and stored in a memory.
• Light sensitive chips also typically include means for selecting the amount of time the light sensitive elements collect light before the data stored therein is read out. Such means can act as an "electronic shutter".
• CCD chips include a control that triggers reading out of pixel data from light-sensitive pixels into vertical data registers that are shielded from light. The inventors have determined that providing an electronic camera with multiple CCD chips allows the camera to capture multiple exposures of a single image simultaneously.
• FIG. 1 shows a sensor layout for an interline transfer charge coupled device (“CCD") 10 of the type used in many electronic cameras.
• CCD 10 comprises a plurality of imaging regions 12 which comprise light sensitive elements, and storage regions which comprise vertical registers 14.
• imaging regions 12 alternate with vertical registers 14 in a horizontal direction.
• Imaging regions 12 each comprise a plurality of pixels 16.
• Each pixel 16 comprises a sensor that stores charge. The amount of stored charge depends upon the number of photons detected by the sensor. As indicated by the arrows in Figure 1, after an image is exposed, pixel data characterizing the charges stored in pixels 16 are shifted to vertical registers 14.
• Vertical registers 14 (which are sometimes referred to as “column registers”) may be covered with an opaque mask layer (e.g. with strips of aluminum) to prevent incoming light from striking vertical registers 14.
• Vertical registers 14 preserve the charges' characteristics as the pixel data is shifted down vertical registers 14 into a horizontal register 18.
• the terms “vertical”, “horizontal” and “down” used in this description refer to the orientation of the elements shown in Figure 1 , rather than to any particular physical orientation.)
• the pixel data is generally read out from horizontal register 18 to an analog-to-digital converter through one or more amplifiers and/or other signal conditioning circuits (not shown).
• FIG. 2 shows an electronic camera 20 equipped with first and second CCDs 1OA and 1OB.
• CCDs 1OA and 1OB may be similar in structure to CCD 10 of Figure 1, but may have different characteristics.
• first CCD 1OA may comprise a high resolution sensor having a normal dynamic range.
• Second CCD 1OB may comprise a low resolution sensor having a high dynamic range.
• the resolution of first CCD 1OA may be, for example, 1920x1080 or higher.
• the resolution of second CCD 1OB may be as low as, for example, 1/4 the resolution of first CCD 1OA in each dimension.
• first CCD 1OA may comprise a color sensor
• second CCD 1OB may comprise a monochrome sensor.
• Camera 20 comprises a mechanical shutter 22 for selectively allowing light from an image to reach CCDs 1OA and 1OB.
• a controller 24 controls the opening and closing of shutter 22 by means of a shutter control line 26.
• Controller 24 also controls the clocking of vertical registers 14 and horizontal register 18 of CCDs 1OA and 1OB by means of CCD control lines 28A and 28B.
• Controller 24 may comprise, for example, a microprocessor running software (e.g. firmware 25). Controller 24 receives pixel data from CCDs 1OA and 1OB by means of data lines 3OA and 3OB.
• Controller 24 may store the pixel data in a memory 32. Controller 24 may store the pixel data in memory 32, for example, in a data structure comprising a first portion containing HDR information, and a second portion containing tone map data, as described in International Application No. PCT/CA2004/002199 filed 24 December 2004, which is hereby incorporated by reference herein. [0021] Controller 24 may also display an image based on the pixel data on a view screen 34. View screen 34 may comprise, for example, a high luminance display to overcome ambient illumination which could make it difficult for a viewer to see the image. Alternatively, view screen 34 may comprise, for example, a high dynamic range display device such as those disclosed in International Application No.
• camera 20 may comprise a hood to shield the high dynamic range display device from ambient illumination.
• Camera 20 also comprises an interface 35 for allowing a user to interact with controller 24.
• Interface 35 includes a shutter release 36.
• Shutter release 36 may be triggered by a timer, an electronic signal, a shutter release button or the like.
• Figure 3 shows a method 100 for producing a high dynamic range (HDR) image using a camera having a plurality of CCDs, such as for example, camera 20 of Figure 2.
• HDR high dynamic range
• method 100 sets the camera's lens to an appropriate aperture.
• the aperture may be set by the camera's exposure control circuit.
• a wide variety of suitable systems for setting the shutter aperture in digital cameras are known in the art. Such systems may set the aperture to a user-determined value or may set the aperture according to an algorithm based upon detected light levels.
• any charge stored in the pixels of first and second CCDs 1OA and 1OB is cleared, and an image capture period begins.
• the camera's timer counts down a predetermined time period for the image capture.
• First and second CCDs 1OA and 1OB may each be exposed for the same duration, but this is not necessary in all embodiments. Additionally or alternatively, either or both of first and second CCDs 1OA and 1OB may be operated to capture multiple exposures during the image capture period, for example, by employing techniques such as those described in United States Patent Applications No.
• time-domain interpolation techniques may be used when combining data from first and second CCDs 1OA and 1OB.
• data representative of the charge stored in the pixels of first and second CCDs 1OA and 1OB is read out at block 108.
• first and second CCDs 1OA and 1OB are each exposed only once, the data may be read out after the image capture period.
• some of the data may be read out during the image capture period and some of the date may be read out after the image capture period.
• data from first and second CCDs 1OA and 1OB is combined to produce a HDR image.
• Combining data from first and second CCDs 1OA and 1OB may comprise, for example, the use of techniques such as those described in International Application No. PCT/CA2004/002199.
• the combined data from first and second CCDs 1OA and 1OB may be stored in a memory.
• the combined data may be stored in a data structure comprising a first portion containing HDR information, and a second portion containing tone map data, as described in International Application No. PCT/CA2004/002199, such that both normal and dynamic range images may be produced from the combined data.
• cameras according to certain embodiments of the invention may comprise more than two CCDs.
• use of more than two CCDs may provide for additional dynamic range and/or colors in the resulting image.
• at least one of the two or more CCDs may be specifically adapted for capturing HDR pixels.
• a controller in a camera may be programmed to combine data from two or more CCDs to yield HDR image data and to store the HDR image data in any suitable HDR format. Where this is done, it can be appreciated that HDR images can be obtained in a way that is essentially transparent to a user.
• Certain implementations of the invention comprise computer processors which execute software instructions which cause the processors to perform a method of the invention.
• processors in a controller for an electronic camera may implement the method of Figure 3 by executing software instructions in a program memory accessible to the processors.
• the invention may also be provided in the form of a program product.
• the program product may comprise any medium which carries a set of computer-readable signals comprising instructions which, when executed by a data processor, cause the data processor to execute a method of the invention.
• Program products according to the invention may be in any of a wide variety of forms.
• the program product may comprise, for example, physical media such as magnetic data storage media including floppy diskettes, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAM, or the like or transmission- type media such as digital or analog communication links.
• the computer- readable signals on the program product may optionally be compressed or encrypted.
• a component e.g. a software module, processor, assembly, device, circuit, etc.
• reference to that component should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.

Landscapes

• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Computing Systems (AREA)
• Theoretical Computer Science (AREA)
• Human Computer Interaction (AREA)
• Studio Devices (AREA)
• Transforming Light Signals Into Electric Signals (AREA)
• Exposure Control For Cameras (AREA)
• Color Television Image Signal Generators (AREA)
• Cameras In General (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (2)

Family

ID=39512472

Family Applications (1)

Country Status (8)

Cited By (1)

Families Citing this family (99)

Citations (2)

Family Cites Families (37)

• 2006
  • 2006-12-12 US US11/609,837 patent/US8242426B2/en active Active
• 2007
  • 2007-12-12 JP JP2009541566A patent/JP5551937B2/ja active Active
  • 2007-12-12 EP EP07865604A patent/EP2123026A4/en not_active Ceased
  • 2007-12-12 CN CN2007800499624A patent/CN101622862B/zh active Active
  • 2007-12-12 WO PCT/US2007/087301 patent/WO2008073991A2/en not_active Ceased
  • 2007-12-12 KR KR1020097014034A patent/KR101449973B1/ko active Active
  • 2007-12-12 MX MX2009006185A patent/MX2009006185A/es active IP Right Grant
  • 2007-12-12 CA CA2672143A patent/CA2672143C/en active Active
• 2012
  • 2012-08-13 US US13/584,597 patent/US8513588B2/en active Active
• 2013
  • 2013-07-15 US US13/942,006 patent/US10033940B2/en active Active
• 2014
  • 2014-04-04 JP JP2014077656A patent/JP2014161055A/ja active Pending
• 2017
  • 2017-01-20 JP JP2017008539A patent/JP6360211B2/ja active Active

Patent Citations (2)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events