WO2018039985A1 - Multi camera system for zoom - Google Patents

Multi camera system for zoom Download PDF

Info

Publication number
WO2018039985A1
WO2018039985A1 PCT/CN2016/097567 CN2016097567W WO2018039985A1 WO 2018039985 A1 WO2018039985 A1 WO 2018039985A1 CN 2016097567 W CN2016097567 W CN 2016097567W WO 2018039985 A1 WO2018039985 A1 WO 2018039985A1
Authority
WO
WIPO (PCT)
Prior art keywords
image sensor
color image
signals
color
pixels
Prior art date
Application number
PCT/CN2016/097567
Other languages
French (fr)
Inventor
Hajime Numata
Wei Luo
Original Assignee
Huawei Technologies Co., Ltd.
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 Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Priority to EP16914551.3A priority Critical patent/EP3497928B1/en
Priority to PCT/CN2016/097567 priority patent/WO2018039985A1/en
Priority to CN201680088745.5A priority patent/CN109644258B/en
Priority to US16/329,224 priority patent/US10616493B2/en
Publication of WO2018039985A1 publication Critical patent/WO2018039985A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/10—Circuitry of solid-state image sensors [SSIS]; Control thereof for transforming different wavelengths into image signals
    • H04N25/11—Arrangement of colour filter arrays [CFA]; Filter mosaics
    • H04N25/13—Arrangement of colour filter arrays [CFA]; Filter mosaics characterised by the spectral characteristics of the filter elements
    • H04N25/134—Arrangement of colour filter arrays [CFA]; Filter mosaics characterised by the spectral characteristics of the filter elements based on three different wavelength filter elements
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T11/00—2D [Two Dimensional] image generation
    • G06T11/001—Texturing; Colouring; Generation of texture or colour
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T3/00—Geometric image transformations in the plane of the image
    • G06T3/40—Scaling of whole images or parts thereof, e.g. expanding or contracting
    • G06T3/4015—Image demosaicing, e.g. colour filter arrays [CFA] or Bayer patterns
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00—Image enhancement or restoration
    • G06T5/50—Image enhancement or restoration using two or more images, e.g. averaging or subtraction
    • 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
    • H04N23/60—Control of cameras or camera modules
    • H04N23/69—Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/80—Camera processing pipelines; Components thereof
    • H04N23/84—Camera processing pipelines; Components thereof for processing colour signals
    • H04N23/843—Demosaicing, e.g. interpolating colour pixel values
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/90—Arrangement of cameras or camera modules, e.g. multiple cameras in TV studios or sports stadiums
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/10—Circuitry of solid-state image sensors [SSIS]; Control thereof for transforming different wavelengths into image signals
    • H04N25/11—Arrangement of colour filter arrays [CFA]; Filter mosaics
    • H04N25/13—Arrangement of colour filter arrays [CFA]; Filter mosaics characterised by the spectral characteristics of the filter elements
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/20—Special algorithmic details
    • G06T2207/20212—Image combination
    • G06T2207/20221—Image fusion; Image merging
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/20—Special algorithmic details
    • G06T2207/20212—Image combination
    • G06T2207/20224—Image subtraction
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2210/00—Indexing scheme for image generation or computer graphics
    • G06T2210/22—Cropping

Definitions

  • the present application relates to a camera built into a smartphone or any other apparatus, and particularly to a camera having a zoom function.
  • the camera built into a smartphone uses a fixed focal lens instead of a zoom lens due to restriction on the size and thickness.
  • the zoom function is achieved as follows:
  • Part of an entire captured image is cropped and electronically enlarged and further caused to undergo sharpness control, super-resolution processing, and other types of detail/resolution enhancement.
  • Two cameras a wide-angle camera and a telephoto camera, are used. Two images from the two cameras are combined with each other in accordance with the zoom position.
  • a problem with the method described in the above item 1 is a decrease in resolution because an image is cropped.
  • an image sensor having a total pixel number of 8M is used to capture an image of 2x zoom magnification
  • the number of pixels of the enlarged image undesirably decreases to 2M.
  • the decrease in the number of pixels lowers the resolution and therefore loses information on details and texture.
  • the method described in the above item 2 has a problem of design (exterior appearance) of the smartphone because a telephoto lens has a long focal length.
  • a telephoto lens is built into a thin smartphone, the portion where the telephoto lens is built in is thicker than the other portion, resulting in deterioration in exterior appearance.
  • An obj ect of the present invention is to provide a zoom camera that not only produces an image the image quality of which is not lost or lost only by a small amount even when the image is zoomed up but also has a thin exterior appearance maintained.
  • a first aspect of the present invention provides a zoom camera.
  • the zoom camera comprises two cameras: a first camera and a second camera.
  • the first camera includes a first lens and a color image sensor covered with color filters located in front of square pixels.
  • the second camera includes a second lens and a mono color image sensor having square pixels, with a pixel arrangement of the mono color image sensor rotated by 45 degrees with respect to a pixel arrangement of the color image sensor.
  • the zoom camera further comprises a first interpolation means for interpolating signals outputted from the color image sensor, converting the interpolated signals into color difference signals, and outputting the color difference signals; a second interpolation means for interpolating signals outputted from the mono color image sensor and outputting interpolated luminance signals; a first cropping means for cropping the color difference signals;
  • a second cropping means for cropping the interpolated luminance signals; and a color image signal processing means for fusing the cropped color difference signals and the cropped luminance signals.
  • both interpolation of signals outputted from the pixels each covered with a green filter in the color image sensor performed by the first interpolation means and interpolation of signals performed by the second interpolation means may use the same algorithm.
  • a focal length of the second lens may be longer than a focal length of the first lens.
  • a total number of pixels provided in the mono color image sensor may be substantially equal to a total number of pixels provided in the color image sensor.
  • a total number of pixels provided in the mono color image sensor may be greater than a total number of pixels provided in the color image sensor.
  • a second aspect of the present invention provides a zoom camera.
  • the zoom camera comprises two cameras: a first camera and a second camera.
  • the first camera includes a first lens and a color image sensor covered with color filters located in front of square pixels.
  • the second camera includes a second lens and a mono color image sensor having square pixels, with a pixel arrangement of the mono color image sensor rotated by 45 degrees with respect to a pixel arrangement of the color image sensor.
  • the zoom camera further comprises a first interpolation means for interpolating signals outputted from the color image sensor, converting the interpolated signals into color difference signals and low-frequency luminance signals, and outputting the color difference signals and the low-frequency luminance signals;
  • a second interpolation means for interpolating signals outputted from the mono color image sensor and outputting high-frequency luminance signals
  • a luminance signal fusing means for fusing the low-frequency luminance signals and the high-frequency luminance signals and outputting fused luminance signals
  • a color image signal processing means for fusing the cropped color difference signals and the cropped luminance signals.
  • FIG. 1 shows a color image sensor covered with Bayer-patterned color filters and a black/white (B/W) image sensor covered with no color filter.
  • FIG. 2 shows pixel arrangement in the diagonal direction.
  • FIG. 3 shows a color image sensor and a black/white image sensor in an embodiment of the present invention.
  • FIG. 4 shows a first example of the configuration of the zoom camera according to the embodiment of the present invention.
  • FIG. 5 shows a second example of the configuration of the zoom camera according to the embodiment of the present invention.
  • FIG. 6 shows a first embodiment of the present invention.
  • FIG. 7 shows a second embodiment of the present invention.
  • the camera in a smartphone and any other similar apparatus typically uses a single-plate image sensor for cost and other reasons.
  • Each pixel of the image sensor only provides information on the luminance of light.
  • the pixels are covered with color filters of three colors (red, green, and blue) .
  • the pattern in accordance with which the color filters are arranged is typically the Bayer pattern.
  • FIG. 1 shows a color image sensor covered with Bayer-patterned color filters and a black/white (B/W) image sensor covered with no color filter.
  • the black/white image sensor used herein is a sensor that detects the grey level of light, and comprises a mono color image sensor.
  • Each pixel typically has a square shape. Assuming that each side of each pixel has a length of 1, the inter-pixel pitch is also 1.
  • the green pixels are arranged in the checkered pattern. That is, as shown in FIG. 1, the green (G) pixel and the red (R) or blue (B) pixel are arranged alternately.
  • a set of three color signals at the position of G 22 pixel shown in FIG. 1 is as follows:
  • Red signal (R 12 +R 32 ) /2
  • the composite color signal at the position of G 22 pixel is composited by the above-mentioned green, red, and blue signals.
  • a luminance signal Y at the position of G 22 pixel is obtained by transforming a set of green, red, and blue signals to a set of the luminance signal Y and color difference signals Cb and Cr.
  • a green row and a red/blue row are alternately arranged in the diagonal direction of the color image sensor.
  • the luminance signals from a color image sensor are typically determined by the signal s from the green pixels, although enhanced by the signals from the red and blue pixels in some cases.
  • the pitch between the green pixels is twice the pitch between the pixels of the black/white image sensor. Therefore, as far as the luminance signals are concerned, the resolution of the color image sensor is half the resolution of the black/white image sensor.
  • FIG. 3 shows a color image sensor and a black/white image sensor in an embodiment of the present invention.
  • a zoom camera according to an embodiment of the present invention includes two cameras.
  • a first camera has a built-in color image sensor covered with Bayer-patterned color filters, and a second camera has a built-in black/white image sensor.
  • the color image sensor and the black/white image sensor may have the same pixel size or different pixel sizes, and the following description will be made with reference to the case where they have the same pixel size for ease of description.
  • the color image sensor and the black/white image sensor have the same square shape pixels. Assuming that each side of each pixel has a length of 1, the inter-pixel pitch is also 1.
  • the pixel arrangement in the black/white image sensor is rotated by 45 degrees with respect to the pixel arrangement in the color image sensor, as shown in FIG. 3 (a) .
  • the green pixels in the color image sensor and the pixels in the black/white image sensor are arranged in the same shape, as shown in FIG. 3 (b) .
  • the inter-pixel pitch in the diagonal direction is, however, 1.4 in the color image sensor and 1.0 in the black/white image sensor.
  • imaginary pixels created by the interpolation are shown between the real pixels in the black/white image sensor.
  • the composite color signal at the position of each pixel includes the interpolation of signals produced by the surrounding pixels.
  • the pitch between pixels after the interpolation is 1 in the color image sensor and 0.71 in the black/white image sensor, as shown in FIG. 3 (d) . It is assumed that the phrase "pixels after the interpolation" include imaginary pixels created by the interpolation.
  • the post-interpolation resolution obtained from the black/white image sensor is 1.4 times the post-interpolation resolution obtained from the color image sensor.
  • the resolution of the enlarged image is equal to the resolution of an interpolated image obtained from the color image sensor. Since the sensitivity of the black/white image sensor is higher than the sensitivity of the color image sensor by the amount reduced by the color filters, the signal to noise ratio (SNR) of the black/white image sensor is also higher than that of the color image sensor.
  • SNR signal to noise ratio
  • FIG. 4 shows a first example of the configuration of the zoom camera according to the embodiment of the present invention.
  • the zoom camera includes a first camera 1 and a second camera 2.
  • the first camera 1 has a first lens 3 and a color image sensor 4 built therein
  • the second camera 2 has a second lens 5 and a black/white image sensor 6 built therein.
  • the pixel arrangement of the black/white image sensor 6 is rotated by 45 degrees with respect to the pixel arrangement of the color image sensor 4.
  • the red, green, and blue signals outputted from the color image sensor 4 are interpolated by a first interpolation means 7 to produce a composite color signal (a set of red, green, and blue signals) at the position of each pixel, and a set of red, green, and blue signals is transformed to a set of a luminance signal Y and color difference signals Cb and Cr.
  • the first interpolation means 7 outputs the color difference signals Cb and Cr.
  • the luminance signals outputted from the black/white image sensor 6 are interpolated by a second interpolation means 8, and interpolated luminance signals Y are outputted.
  • the color difference signals Cb and Cr are inputted to first cropping means 9, which cuts out a necessary range from the entire image.
  • the interpolated luminance signals Y are inputted to a second cropping means 10, which also cuts out a necessary range from the entire image.
  • the color difference signals and the luminance signals after the cropping are fused by a color image signal processing means 11.
  • the resolution of the color difference signals is lower than the resolution of the luminance signals, but the difference in the resolution will not cause a viewer to feel that the image is unnatural because the color resolution of the human eye is lower than the luminance resolution thereof.
  • FIG. 5 shows a second example of the configuration of the zoom camera according to the embodiment of the present invention.
  • low-frequency luminance signals Ylow outputted from the first interpolation means 7 are also used.
  • the first interpolation means 7 produces the color difference signals Cb and Cr and the low-frequency luminance signals Ylow from the color signals, and the low-frequency luminance signals Ylow are inputted to a luminance signal fusing means 13.
  • the interpolated luminance signals outputted from the second interpolation means 8 (high-frequency luminance signals Yhigh) pass through a highpass/bandpass filter 12 and are then inputted to the luminance signal fusing means 13.
  • the low-frequency luminance signals Ylow and the high-frequency luminance signals Yhigh are fused by the luminance signal fusing means 13, and fused luminance signals Y'are inputted to the second cropping means 10.
  • the other configurations are the same as those in the first example.
  • FIG. 6 shows a first embodiment of the present invention.
  • the first camera uses a wide-angle lens and the second camera uses a telephoto lens, and the field of view (FOV) of the first camera is set to be about twice the field of view of the second camera.
  • the focal length of the second lens is twice the focal length of the first lens.
  • An image obtained from the first camera and an image obtained from the second camera are fused to achieve "zooming" .
  • the total number of pixels of the color image sensor is substantially equal to the total number of pixels of the black/white image sensor.
  • a 2x optical "zoom" lens two lenses having different focal lengths in practice
  • the pixel arrangement of the black/white image sensor is rotated by 45 degrees with respect to the pixel arrangement of the color image sensor. Therefore, as far as the luminance single is concerned, the pitch between the interpolated pixels obtained from the black/white image sensor is about 0.71 (1/ (the square root of 2) ) times the pitch between the interpolated pixels obtained from the color image sensor.
  • the post-interpolation resolution obtained from the black/white image sensor is therefore about 1.4 (the square root of 2) times the post-interpolation resolution obtained from the color image sensor. This means that an image obtained from the black/white image sensor can be cropped and enlarged by a factor of about 1.4 times at the maximum with no decrease in the resolution, as compared with an image obtained from the color image sensor.
  • the total zoom ratio is the product of the optical zoom ratio and the cropping-related zoom ratio, about 3x zooming can be achieved.
  • the optical zoom ratio since the optical zoom ratio only needs to be 2x, the focal length of the lens can be shortened as compared with a case where 3x optical zooming is provided. As a result, the overall length of the camera can be shortened.
  • FIG. 7 shows a second embodiment of the present invention.
  • Setting the total number of pixels of the black/white image sensor to be greater than the total number of pixels of the color image sensor allows a higher zoom ratio to be achieved.
  • setting the total number of pixels of the black/white image sensor at 17M pixels with respect to the total number of pixels of 12M pixels in the color image sensor allows an increase in the resolution by a factor of about 1.7 because the number of pixels increases.
  • Use of 2x optical zooming tilt-longer-focal-length lens in practice

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Human Computer Interaction (AREA)
  • Studio Devices (AREA)
  • Color Television Image Signal Generators (AREA)

Abstract

An aspect of the present invention provides a zoom camera comprising: a first camera including a first lens and a color image sensor covered with color filters located in front of square pixels;a second camera including a second lens and a mono color image sensor having square pixels, with a pixel arrangement of the mono color image sensor rotated by 45 degrees with respect to a pixel arrangement of the color image sensor;a first interpolation means for interpolating signals outputted from the color image sensor, converting the interpolated signals into color difference signals, and outputting the color difference signals;a second interpolation means for interpolating signals outputted from the mono color image sensor and outputting interpolated luminance signals;a first cropping means for cropping the color difference signals;a second cropping means for cropping the interpolated luminance signals;and a color image signal processing means for fusing the cropped color difference signals and the cropped luminance signals.

Description

MULTI CAMERA SYSTEM FOR ZOOM Technical Field
The present application relates to a camera built into a smartphone or any other apparatus, and particularly to a camera having a zoom function.
Background
At present, most smartphones each have a camera built therein. The performance of the camera built into a smartphone has been improved and is now comparable to the performance of a digital still camera (DSC) and a digital single lens reflex camera (DSLR camera) . To further expand the range of the application of the camera built into a smartphone, a high-quality zoom function has been increasingly required.
In general, the camera built into a smartphone uses a fixed focal lens instead of a zoom lens due to restriction on the size and thickness. The zoom function is achieved as follows:
1. Electronic signal processing
Part of an entire captured image is cropped and electronically enlarged and further caused to undergo sharpness control, super-resolution processing, and other types of detail/resolution enhancement.
2. Use of two cameras
Two cameras, a wide-angle camera and a telephoto camera, are used. Two images from the two cameras are combined with each other in accordance with the zoom position.
A problem with the method described in the above item 1 is a decrease in resolution because an image is cropped. For example, when an image sensor having a total pixel number of 8M is used to capture an image of 2x zoom magnification, the number of pixels of the enlarged image undesirably decreases to 2M. The decrease in the number of pixels lowers the resolution and therefore loses information on details and texture. Even when sharpness control and super-resolution processing are performed, it cannot be said that a lossless zoom function is achieved, and image quality of details is inferior to that achieved by optical zooming.
The method described in the above item 2 has a problem of design (exterior appearance) of the smartphone because a telephoto lens has a long focal length. When a telephoto lens is built into a thin smartphone, the portion where the telephoto lens is built in is thicker than the other portion, resulting in deterioration in exterior appearance.
Summary
An obj ect of the present invention is to provide a zoom camera that not only produces an image the image quality of which is not lost or lost only by a small amount even when the image is zoomed up but also has a thin exterior appearance maintained.
A first aspect of the present invention provides a zoom camera. The zoom camera comprises two cameras: a first camera and a second camera. The first camera includes a first lens and a color image sensor covered with color filters located in front of square pixels. The second camera includes a second lens and a mono color image sensor having square pixels, with a pixel arrangement of the mono color image sensor rotated by 45 degrees with respect to a pixel arrangement of the color image sensor. The zoom camera further comprises a first interpolation means for interpolating signals outputted from the color image sensor, converting the interpolated signals into color difference signals, and outputting the color difference signals； a second interpolation means for interpolating signals outputted from the mono color image sensor and outputting interpolated luminance signals； a first cropping means for cropping the color difference signals；
a second cropping means for cropping the interpolated luminance signals； and a color image  signal processing means for fusing the cropped color difference signals and the cropped luminance signals.
When Bayer patterned color filters are used, both interpolation of signals outputted from the pixels each covered with a green filter in the color image sensor performed by the first interpolation means and interpolation of signals performed by the second interpolation means may use the same algorithm.
A focal length of the second lens may be longer than a focal length of the first lens.
A total number of pixels provided in the mono color image sensor may be substantially equal to a total number of pixels provided in the color image sensor.
A total number of pixels provided in the mono color image sensor may be greater than a total number of pixels provided in the color image sensor.
A second aspect of the present invention provides a zoom camera. The zoom camera comprises two cameras: a first camera and a second camera.
The first camera includes a first lens and a color image sensor covered with color filters located in front of square pixels.
The second camera includes a second lens and a mono color image sensor having square pixels, with a pixel arrangement of the mono color image sensor rotated by 45 degrees with respect to a pixel arrangement of the color image sensor.
The zoom camera further comprises a first interpolation means for interpolating signals outputted from the color image sensor, converting the interpolated signals into color difference signals and low-frequency luminance signals, and outputting the color difference signals and the low-frequency luminance signals；
a second interpolation means for interpolating signals outputted from the mono color image sensor and outputting high-frequency luminance signals；
a luminance signal fusing means for fusing the low-frequency luminance signals and the high-frequency luminance signals and outputting fused luminance signals；
a first cropping means for cropping the color difference signals；
a second cropping means for cropping the fused luminance signals； and
a color image signal processing means for fusing the cropped color difference signals and the cropped luminance signals.
Brief Description of Drawings
FIG. 1 shows a color image sensor covered with Bayer-patterned color filters and a black/white (B/W) image sensor covered with no color filter.
FIG. 2 shows pixel arrangement in the diagonal direction.
FIG. 3 shows a color image sensor and a black/white image sensor in an embodiment of the present invention.
FIG. 4 shows a first example of the configuration of the zoom camera according to the embodiment of the present invention.
FIG. 5 shows a second example of the configuration of the zoom camera according to the embodiment of the present invention.
FIG. 6 shows a first embodiment of the present invention.
FIG. 7 shows a second embodiment of the present invention.
Description of Embodiments
The camera in a smartphone and any other similar apparatus typically uses a single-plate image sensor for cost and other reasons. Each pixel of the image sensor only provides information on the luminance of light. To produce a color image, the pixels are covered with color filters of three colors (red, green, and blue) . The pattern in accordance with which the color filters are arranged is typically the Bayer pattern.
FIG. 1 shows a color image sensor covered with Bayer-patterned color filters and a black/white (B/W) image sensor covered with no color filter. The black/white image sensor used herein is a sensor that detects the grey level of light, and comprises a mono color image sensor. Each pixel typically has a square shape. Assuming that each side of each pixel has a length of 1, the inter-pixel pitch is also 1.
In the Bayer-patterned color filter configuration, color filters of the three colors are arranged on 2 × 2 ＝4 pixels. Since the human eye is most sensitive to green, the green signal most greatly contributes to the luminance signal (Y signal) . Therefore, green is assigned to two pixels, and red and blue are assigned to the other two pixels respectively. The green pixels are arranged in the checkered pattern. That is, as shown in FIG. 1, the green (G) pixel and the red (R) or blue (B) pixel are arranged alternately.
Since one pixel produces only one color signal, the other two color signals are produced by using an image signal processor (ISP) to perform interpolation (de-mosaic) of signals produced by the surrounding pixels. For example, a set of three color signals at the position of G22 pixel shown in FIG. 1 is as follows:
Green signal＝G22
Red signal＝ (R12+R32) /2
Blue signal＝ (B21+B23) /2
The composite color signal at the position of G22 pixel is composited by the above-mentioned green, red, and blue signals. A luminance signal Y at the position of G22 pixel is obtained by transforming a set of green, red, and blue signals to a set of the luminance signal Y and color difference signals Cb and Cr.
Referring to FIG. 2 showing pixel arrangement in the diagonal direction, a green row and a red/blue row are alternately arranged in the diagonal direction of the color image sensor.
The luminance signals from a color image sensor are typically determined by the signal s from the green pixels, although enhanced by the signals from the red and blue pixels in some cases. The pitch between the green pixels is twice the pitch between the pixels of the black/white image sensor. Therefore, as far as the luminance signals are concerned, the resolution of the color image sensor is half the resolution of the black/white image sensor.
FIG. 3 shows a color image sensor and a black/white image sensor in an embodiment of the present invention. A zoom camera according to an embodiment of the present invention includes two cameras. A first camera has a built-in color image sensor covered with Bayer-patterned  color filters, and a second camera has a built-in black/white image sensor. The color image sensor and the black/white image sensor may have the same pixel size or different pixel sizes, and the following description will be made with reference to the case where they have the same pixel size for ease of description. The color image sensor and the black/white image sensor have the same square shape pixels. Assuming that each side of each pixel has a length of 1, the inter-pixel pitch is also 1.
The pixel arrangement in the black/white image sensor is rotated by 45 degrees with respect to the pixel arrangement in the color image sensor, as shown in FIG. 3 (a) .
The green pixels in the color image sensor and the pixels in the black/white image sensor are arranged in the same shape, as shown in FIG. 3 (b) . The inter-pixel pitch in the diagonal direction is, however, 1.4 in the color image sensor and 1.0 in the black/white image sensor.
In the lower figure of FIG. 3 (c) , imaginary pixels created by the interpolation are shown between the real pixels in the black/white image sensor. On the other hand, in the color image sensor, the composite color signal at the position of each pixel includes the interpolation of signals produced by the surrounding  pixels. The pitch between pixels after the interpolation is 1 in the color image sensor and 0.71 in the black/white image sensor, as shown in FIG. 3 (d) . It is assumed that the phrase "pixels after the interpolation" include imaginary pixels created by the interpolation. The post-interpolation resolution obtained from the black/white image sensor is 1.4 times the post-interpolation resolution obtained from the color image sensor. Therefore, even when an interpolated image obtained from the black/white image sensor is cropped and then enlarged by a factor of 1.4, the resolution of the enlarged image is equal to the resolution of an interpolated image obtained from the color image sensor. Since the sensitivity of the black/white image sensor is higher than the sensitivity of the color image sensor by the amount reduced by the color filters, the signal to noise ratio (SNR) of the black/white image sensor is also higher than that of the color image sensor.
FIG. 4 shows a first example of the configuration of the zoom camera according to the embodiment of the present invention. The zoom camera includes a first camera 1 and a second camera 2. The first camera 1 has a first lens 3 and a color image sensor 4 built therein, and the second camera 2 has a second lens 5 and a black/white image sensor 6 built therein. The pixel arrangement of the black/white image sensor 6 is rotated  by 45 degrees with respect to the pixel arrangement of the color image sensor 4.
The red, green, and blue signals outputted from the color image sensor 4 are interpolated by a first interpolation means 7 to produce a composite color signal (a set of red, green, and blue signals) at the position of each pixel, and a set of red, green, and blue signals is transformed to a set of a luminance signal Y and color difference signals Cb and Cr. The first interpolation means 7 outputs the color difference signals Cb and Cr.
The luminance signals outputted from the black/white image sensor 6 are interpolated by a second interpolation means 8, and interpolated luminance signals Y are outputted.
The color difference signals Cb and Cr are inputted to first cropping means 9, which cuts out a necessary range from the entire image. The interpolated luminance signals Y are inputted to a second cropping means 10, which also cuts out a necessary range from the entire image. The color difference signals and the luminance signals after the cropping are fused by a color image signal processing means 11. The resolution of the color difference signals is lower than the resolution of the luminance signals, but the difference in the resolution will not cause a viewer to feel that the image is  unnatural because the color resolution of the human eye is lower than the luminance resolution thereof.
FIG. 5 shows a second example of the configuration of the zoom camera according to the embodiment of the present invention. In this example, low-frequency luminance signals Ylow outputted from the first interpolation means 7 are also used.
The first interpolation means 7 produces the color difference signals Cb and Cr and the low-frequency luminance signals Ylow from the color signals, and the low-frequency luminance signals Ylow are inputted to a luminance signal fusing means 13. The interpolated luminance signals outputted from the second interpolation means 8 (high-frequency luminance signals Yhigh) pass through a highpass/bandpass filter 12 and are then inputted to the luminance signal fusing means 13. The low-frequency luminance signals Ylow and the high-frequency luminance signals Yhigh are fused by the luminance signal fusing means 13, and fused luminance signals Y'are inputted to the second cropping means 10. The other configurations are the same as those in the first example.
FIG. 6 shows a first embodiment of the present invention. In this embodiment, the first camera uses a wide-angle lens and the second camera uses a telephoto  lens, and the field of view (FOV) of the first camera is set to be about twice the field of view of the second camera. The focal length of the second lens is twice the focal length of the first lens. An image obtained from the first camera and an image obtained from the second camera are fused to achieve "zooming" . The total number of pixels of the color image sensor is substantially equal to the total number of pixels of the black/white image sensor. According to this embodiment, a 2x optical "zoom" lens (two lenses having different focal lengths in practice) can be used to achieve about 3x "zooming" .
Specifically, the total number of pixels of the color image sensor is 3000 × 4000 ＝ 12M pixels, and the total number of pixels of the black/white image sensor is substantially the same.
The pixel arrangement of the black/white image sensor is rotated by 45 degrees with respect to the pixel arrangement of the color image sensor. Therefore, as far as the luminance single is concerned, the pitch between the interpolated pixels obtained from the black/white image sensor is about 0.71 (1/ (the square root of 2) ) times the pitch between the interpolated pixels obtained from the color image sensor. The post-interpolation resolution obtained from the black/white image sensor is therefore about 1.4 (the square root of 2) times the post-interpolation resolution obtained from the color  image sensor. This means that an image obtained from the black/white image sensor can be cropped and enlarged by a factor of about 1.4 times at the maximum with no decrease in the resolution, as compared with an image obtained from the color image sensor.
Since the total zoom ratio is the product of the optical zoom ratio and the cropping-related zoom ratio, about 3x zooming can be achieved. In this case, since the optical zoom ratio only needs to be 2x, the focal length of the lens can be shortened as compared with a case where 3x optical zooming is provided. As a result, the overall length of the camera can be shortened.
FIG. 7 shows a second embodiment of the present invention. Setting the total number of pixels of the black/white image sensor to be greater than the total number of pixels of the color image sensor allows a higher zoom ratio to be achieved. For example, setting the total number of pixels of the black/white image sensor at 17M pixels with respect to the total number of pixels of 12M pixels in the color image sensor allows an increase in the resolution by a factor of about 1.7 because the number of pixels increases. Use of 2x optical zooming (twice-longer-focal-length lens in practice) allows about 3.4x zooming to be achieved.

Claims (10)

  1. A zoom camera comprising:
    a first camera including a first lens and a color image sensor covered with color filters located in front of square pixels；
    a second camera including a second lens and a mono color image sensor having square pixels, with a pixel arrangement of the mono color image sensor rotated by 45 degrees with respect to a pixel arrangement of the color image sensor；
    a first interpolation means for interpolating signals outputted from the color image sensor, converting the interpolated signals into color difference signals, and outputting the color difference signals；
    a second interpolation means for interpolating signals outputted from the mono color image sensor and outputting interpolated luminance signals；
    a first cropping means for cropping the color difference signals；
    a second cropping means for cropping the interpolated luminance signals； and
    a color image signal processing means for fusing the cropped color difference signals and the cropped luminance signals.
  2. The zoom camera according to claim 1, wherein the color filters are Bayer patterned color filters, and both interpolation of signals outputted from the pixels each  covered with a green filter in the color image sensor performed by the first interpolation means and interpolation of signals performed by the second interpolation means use the same algorithm.
  3. The zoom camera according to claim 1 or 2, wherein a focal length of the second lens is longer than a focal length of the first lens.
  4. The zoom camera according to any one of claims 1 to 3, wherein a total number of pixels provided in the mono color image sensor is substantially equal to a total number of pixels provided in the color image sensor.
  5. The zoom camera according to any one of claims 1 to 3, wherein a total number of pixels provided in the mono color image sensor is greater than a total number of pixels provided in the color image sensor.
  6. A zoom camera comprising:
    a first camera including a first lens and a color image sensor covered with color filters located in front of square pixels；
    a second camera including a second lens and a mono color image sensor having square pixels, with a pixel arrangement of the mono color image sensor rotated by 45 degrees with respect to a pixel arrangement of the color image sensor；
    a first interpolation means for interpolating signals outputted from the color image sensor, converting the interpolated signals into color difference signals and low-frequency luminance signals, and outputting the color difference signals and the low-frequency luminance signals；
    a second interpolation means for interpolating signals outputted from the mono color image sensor and outputting high-frequency luminance signals；
    a luminance signal fusing means for fusing the low-frequency luminance signals and the high-frequency luminance signals and outputting fused luminance signals；
    a first cropping means for cropping the color difference signals；
    a second cropping means for cropping the fused luminance signals； and
    a color image signal processing means for fusing the cropped color difference signals and the cropped luminance signals.
  7. The zoom camera according to claim 6, wherein the color filters are Bayer patterned color filters, and both interpolation of signals outputted from the pixels each covered with a green filter in the color image sensor performed by the first interpolation means and interpolation of signals performed by the second interpolation means use the same algorithm.
  8. The zoom camera according to claim 6 or 7, wherein a focal length of the second lens is longer than a focal length of the first lens.
  9. The zoom camera according to any one of claims 6 to 8, wherein a total number of pixels provided in the mono color image sensor is substantially equal to a total number of pixels provided in the color image sensor.
  10. The zoom camera according to any one of claims 6 to 8, wherein a total number of pixels provided in the mono color image sensor is greater than a total number of pixels provided in the color image sensor.
PCT/CN2016/097567 2016-08-31 2016-08-31 Multi camera system for zoom WO2018039985A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP16914551.3A EP3497928B1 (en) 2016-08-31 2016-08-31 Multi camera system for zoom
PCT/CN2016/097567 WO2018039985A1 (en) 2016-08-31 2016-08-31 Multi camera system for zoom
CN201680088745.5A CN109644258B (en) 2016-08-31 2016-08-31 Multi-camera system for zoom photography
US16/329,224 US10616493B2 (en) 2016-08-31 2016-08-31 Multi camera system for zoom

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2016/097567 WO2018039985A1 (en) 2016-08-31 2016-08-31 Multi camera system for zoom

Publications (1)

Publication Number Publication Date
WO2018039985A1 true WO2018039985A1 (en) 2018-03-08

Family

ID=61299817

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2016/097567 WO2018039985A1 (en) 2016-08-31 2016-08-31 Multi camera system for zoom

Country Status (4)

Country Link
US (1) US10616493B2 (en)
EP (1) EP3497928B1 (en)
CN (1) CN109644258B (en)
WO (1) WO2018039985A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108377325A (en) * 2018-05-21 2018-08-07 Oppo广东移动通信有限公司 Filming apparatus, electronic equipment and image acquiring method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021196208A1 (en) * 2020-04-03 2021-10-07 深圳市大疆创新科技有限公司 Image processing method, zoom camera, camera load device, and unmanned aerial vehicle

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080030592A1 (en) * 2006-08-01 2008-02-07 Eastman Kodak Company Producing digital image with different resolution portions
CN101309360A (en) * 2007-05-17 2008-11-19 索尼株式会社 Video input processor, imaging signal-processing circuit, and method for reducing noises in imaging signals
US20080316329A1 (en) * 2007-06-20 2008-12-25 Samsung Electro-Mechanics Co., Ltd. Camera module
CN102177585A (en) * 2008-10-16 2011-09-07 全视科技有限公司 Image sensor having multiple sensing layers and its method of operation and fabrication
US20120044328A1 (en) * 2010-08-17 2012-02-23 Apple Inc. Image capture using luminance and chrominance sensors
CN104519327A (en) * 2013-10-07 2015-04-15 联咏科技股份有限公司 Image sensor and image acquisition system

Family Cites Families (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7057647B1 (en) * 2000-06-14 2006-06-06 E-Watch, Inc. Dual-mode camera system for day/night or variable zoom operation
EP1812968B1 (en) 2004-08-25 2019-01-16 Callahan Cellular L.L.C. Apparatus for multiple camera devices and method of operating same
CN1747556A (en) * 2004-09-10 2006-03-15 上海杰得微电子有限公司 Method for realizing array image interpolation hard soft reposition of color sensor
US7206136B2 (en) 2005-02-18 2007-04-17 Eastman Kodak Company Digital camera using multiple lenses and image sensors to provide an extended zoom range
JP5151075B2 (en) 2005-06-21 2013-02-27 ソニー株式会社 Image processing apparatus, image processing method, imaging apparatus, and computer program
KR101733443B1 (en) 2008-05-20 2017-05-10 펠리칸 이매징 코포레이션 Capturing and processing of images using monolithic camera array with heterogeneous imagers
US8134589B2 (en) * 2008-07-17 2012-03-13 Eastman Kodak Company Zoom by multiple image capture
US8068153B2 (en) 2009-03-27 2011-11-29 Omnivision Technologies, Inc. Producing full-color image using CFA image
US20120113266A1 (en) * 2009-04-07 2012-05-10 Nextvision Stabilized Systems Ltd Methods of manufacturing a camera system having multiple image sensors
WO2012007791A1 (en) * 2010-07-13 2012-01-19 Nokia Corporation Color image sensing
JP6099009B2 (en) 2012-02-16 2017-03-22 パナソニックＩｐマネジメント株式会社 Imaging device and imaging apparatus
CN105556944B (en) * 2012-11-28 2019-03-08 核心光电有限公司 Multiple aperture imaging system and method
US9363425B2 (en) 2012-12-06 2016-06-07 Semiconductor Components Industries, Llc Color filter arrangements for fused array imaging systems
US9443335B2 (en) * 2013-09-18 2016-09-13 Blackberry Limited Using narrow field of view monochrome camera for producing a zoomed image
US9223118B2 (en) 2013-10-31 2015-12-29 Apple Inc. Small form factor telephoto camera
CN105323567B (en) * 2014-07-11 2017-07-28 恒景科技股份有限公司 Color management system and device
US9319585B1 (en) * 2014-12-18 2016-04-19 Omnivision Technologies, Inc. High resolution array camera

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080030592A1 (en) * 2006-08-01 2008-02-07 Eastman Kodak Company Producing digital image with different resolution portions
CN101309360A (en) * 2007-05-17 2008-11-19 索尼株式会社 Video input processor, imaging signal-processing circuit, and method for reducing noises in imaging signals
US20080316329A1 (en) * 2007-06-20 2008-12-25 Samsung Electro-Mechanics Co., Ltd. Camera module
CN102177585A (en) * 2008-10-16 2011-09-07 全视科技有限公司 Image sensor having multiple sensing layers and its method of operation and fabrication
US20120044328A1 (en) * 2010-08-17 2012-02-23 Apple Inc. Image capture using luminance and chrominance sensors
CN104519327A (en) * 2013-10-07 2015-04-15 联咏科技股份有限公司 Image sensor and image acquisition system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP3497928A4 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108377325A (en) * 2018-05-21 2018-08-07 Oppo广东移动通信有限公司 Filming apparatus, electronic equipment and image acquiring method

Also Published As

Publication number Publication date
EP3497928B1 (en) 2020-11-18
EP3497928A1 (en) 2019-06-19
CN109644258B (en) 2020-06-02
EP3497928A4 (en) 2019-07-31
US10616493B2 (en) 2020-04-07
US20190253634A1 (en) 2019-08-15
CN109644258A (en) 2019-04-16

Similar Documents

Publication Publication Date Title
US20180160040A1 (en) High resolution thin multi-aperture imaging systems
US7453510B2 (en) Imaging device
US9215389B2 (en) Image pickup device, digital photographing apparatus using the image pickup device, auto-focusing method, and computer-readable medium for performing the auto-focusing method
JP5066851B2 (en) Imaging device
IL263957A (en) Dual aperture zoom digital camera
JP6802372B2 (en) Shooting method and terminal for terminal
US20120262607A1 (en) Multocular image pickup apparatus and multocular image pickup method
JP2005303694A (en) Compound eye imaging device
US9369693B2 (en) Stereoscopic imaging device and shading correction method
JP5470458B2 (en) Imaging apparatus, image processing apparatus, and image processing method
US20110141321A1 (en) Method and apparatus for transforming a lens-distorted image to a perspective image in bayer space
CN108781250A (en) Video camera controller, camera shooting control method and photographic device
US9148552B2 (en) Image processing apparatus, image pickup apparatus, non-transitory storage medium storing image processing program and image processing method
TWI599809B (en) Lens module array, image sensing device and fusing method for digital zoomed images
CN112991245A (en) Double-shot blurring processing method and device, electronic equipment and readable storage medium
JP6045208B2 (en) Imaging device
JP5348258B2 (en) Imaging device
WO2013027507A1 (en) Imaging device
JP7052811B2 (en) Image processing device, image processing method and image processing system
EP3649772B1 (en) Imaging apparatus with second imaging element used for correcting vignetting in images captured by first imaging element
US10616493B2 (en) Multi camera system for zoom
JP2013085176A (en) Image-capturing device
KR102619738B1 (en) Signal processing devices and imaging devices
WO2015186510A1 (en) Imaging device and method, and program
JP5640383B2 (en) Imaging device

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 16914551

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2016914551

Country of ref document: EP

Effective date: 20190315