JP2005167831A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus by which operation amount during image processing can be reduced. <P>SOLUTION: The imaging apparatus is composed of an image pick-up section 2 which receives incident light from an imaging object and subjects it to photoelectric conversion and an image processor 3 which processes a photographed image outputted from the imaging section 2. The image processor 3 digitizes the photographed image into a digital image which is composed of vertically and horizontally arranged pixels and subjects the digital image to spatial filtering processing by using a spatial filter 40 provided with interleaved lines 42 where no filter coefficient exists. In this manner, by using the spatial filter 40 provided with the interleaved lines 42, the operation amount during image processing can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus that outputs a captured image after performing spatial filtering.

2. Description of the Related Art Conventionally, as an imaging apparatus, as described in, for example, Japanese Patent Laid-Open No. 5-56341, an apparatus that photoelectrically converts light incident through an imaging optical system and outputs it is known. This image pickup apparatus controls the amount of light transmitted to the image pickup optical system and the light accumulation time of the image pickup element, and also variably controls the gain of the image pickup element output, and shortens the setting of the light accumulation time in a predetermined shooting mode. The control is performed so as to increase the gain in order to make time, and an optimum exposure control is realized regardless of the photographing situation.
Japanese Patent Laid-Open No. 5-56341

  However, even with such an imaging apparatus, halation may occur in the captured image depending on the shooting environment. For example, when the imaging device is used in a visual assistance system that provides visual assistance to the driver when the vehicle travels at night, the imaging output is set high in order to visually recognize a pedestrian in front of the vehicle under dark conditions. However, in such a setting state, the influence of halation is great, such as when receiving the headlight of an oncoming vehicle, and appropriate photographing cannot be performed.

  On the other hand, in order to prevent halation, it is conceivable to handle the captured image by image processing. For example, halation can be reduced by applying an appropriate filter process to the photographed image.

  However, when filtering a photographed image, there is a problem that the calculation load becomes large and smooth video output becomes difficult.

  Therefore, the present invention has been made to solve such problems, and an object thereof is to provide an imaging apparatus capable of reducing the amount of calculation in image processing.

  That is, an imaging apparatus according to the present invention includes an imaging unit that receives incident light from an imaging target and performs photoelectric conversion, and an image processing unit that performs image processing on a captured image output from the imaging unit. The processing means is characterized in that the captured image is digitized to form a digital image in which pixels are arranged vertically and horizontally, and the digital image is subjected to spatial filter processing using a spatial filter provided with thinning lines having no filter coefficients.

  The imaging apparatus according to the present invention is characterized in that the thinning line is provided in the horizontal direction of the spatial filter. Moreover, the imaging apparatus according to the present invention is characterized in that the thinning line is provided in the vertical direction of the spatial filter.

  According to these inventions, by providing the thinning line in the spatial filter, it is possible to reduce the amount of calculation when performing the spatial filter processing. Therefore, the spatial filter process can be performed quickly.

  In the imaging apparatus according to the present invention, the above-described imaging unit sequentially reads out the field image by the interlace method, and the above-described image processing unit uses the spatial filter in which the thinned line corresponds to the blank line in the field image. Filtering is performed.

  The image pickup apparatus according to the present invention is characterized in that the above-described spatial filter is provided with thinning lines extending in the horizontal direction every other line in the vertical direction.

  According to these inventions, by performing the spatial filter processing using the spatial filter in which the thinned lines correspond to the blank lines of the field image, it is possible to omit the arithmetic processing on the blank lines of the field image, and The amount of calculation can be reduced.

  In the imaging apparatus according to the present invention, it is preferable that the spatial filter removes a predetermined low-frequency component in the captured image. Moreover, it is preferable that the imaging device which concerns on this invention is mounted in a vehicle and image | photographs a vehicle advancing direction.

  Moreover, it is preferable that the imaging device according to the present invention is used in a visual assistance system that provides visual assistance to the driver when the vehicle travels at night.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device which can reduce the computational amount of image processing can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic configuration diagram of an imaging apparatus according to the first embodiment.

  As shown in the figure, the imaging apparatus 1 according to the present embodiment includes an imaging unit 2 and an image processing unit 3. The imaging unit 2 functions as an imaging unit that receives incident light from an imaging target and performs photoelectric conversion. For example, a CCD (Charge-Coupled Device) camera is used. The imaging unit 2 incorporates a CCD 2a as an imaging element, and a photographing optical system 2b is installed in front of the CCD 2a.

  As the imaging unit 2, for example, a unit that outputs a captured image signal by an interlace method is used. More specifically, one piece of image information (frame image information) is read by being divided into an odd field image and a divisor field image, and an odd field image and an even field image of each frame image are sequentially output. The odd field image is an image obtained by reading only the odd lines of the frame image, and the even field image is an image obtained by reading only the even lines of the frame image.

  The image processing unit 3 functions as an image processing unit that performs image processing on a captured image output from the imaging unit 2, and includes, for example, an A / D conversion unit 31, a spatial filter unit 32, and a D / A conversion unit 33. Configured. The A / D conversion unit 31 is an A / D conversion unit that converts an imaging signal that is an analog signal into a digital signal. For example, the A / D conversion unit 31 individually performs A / D (Analog to Digital) conversion on each image in the odd field and the even field in the interlaced captured image signal.

  The spatial filter unit 32 performs a spatial filter process on the digitally converted captured image. The spatial filter unit 32 sequentially performs spatial filter processing on the odd field and even field images digitally converted by the A / D converter 31. The D / A converter 33 is a D / A (Digital to Analog) converter that converts the output signal of the spatial filter unit 32 from a digital signal to an analog signal.

  The D / A converter 33 analog-converts the image subjected to the spatial filter processing by the spatial filter unit 32 and outputs it as a video signal. For example, an odd field image and an even field image output from the spatial filter unit 32 are combined to form a frame image, and the frame image is converted into an analog signal and output as a video signal. At that time, every time an odd field image or an even field image is output from the spatial filter unit 32, the output field image is replaced with a part of the frame image formed before output to form a new frame image. Is preferred. By forming a frame image in this way, it is possible to output a frame image every time a field image is output, and it is possible to quickly output an image with little image quality degradation from the imaging apparatus 1.

  FIG. 2 is an explanatory diagram of a spatial filter used in the spatial filter unit. FIG. 3 is an explanatory diagram of a digitized field image.

  As shown in FIG. 2, the spatial filter unit 32 performs a spatial filter process using a spatial filter 40 provided with a thinning line 42 where no filter coefficient 41 exists. When the spatial filter 40 is, for example, a 5 × 5 filter, a thinning line 42 is provided in the second and fourth stages in the horizontal direction. The filter coefficient 41 is not assigned to the thinning line 42, and the filter coefficient 41 does not exist. For this reason, even if the filter has a size of 5 × 5, the filter coefficient 41 is 15 instead of 25. A to O in FIG. 2 are filter coefficients.

  As shown in FIG. 3, the field image 50 digitally converted by the A / D converter 31 has blank lines 51 every other pixel in the vertical direction. For example, the luminance value of the pixel of the blank line 51 is set to zero, and the image data of the captured image is not assigned. This is because the captured image output from the imaging unit 2 is an interlaced video.

  Next, the operation of the imaging apparatus according to this embodiment will be described.

  In FIG. 1, a captured image captured by the image capturing unit 2 is read out in an interlaced manner, and an odd field image and an even field image are sequentially input to the A / D conversion unit 31. The A / D converter 31 individually converts the odd field image and the even field image into digital images. Then, the digital image is input to the spatial filter unit 32.

  The spatial filter unit 32 individually performs spatial filter processing on the digitized odd field image and even field image. That is, as shown in FIG. 3, the spatial filter 40 sequentially performs convolution operations on pixels other than the blank line 52 of the field image 50, and repeats the product-sum operation to perform spatial filter processing.

  At this time, no arithmetic processing is required for the blank line 52 of the field image 50. Then, by providing the thinning line 42 in the spatial filter 40 corresponding to the blank line 52, it is possible to greatly reduce the amount of calculation in the spatial filter processing.

  More specifically, when the field image 50 is an image having a size of m × n and the spatial filter 40 is a filter having a size of 5 × 5, the calculation amount in the spatial filter processing is ((m / 2 ) × n) × (5 × 3) = 7.5 (m × n).

  On the other hand, when a spatial filter process is performed on a non-interlaced image of m × n size using a normal 5 × 5 spatial filter without the thinning line 42, the amount of computation is (m × n ) × (5 × 5) = 25 (m × n).

  As described above, in the imaging apparatus according to the present embodiment, the amount of calculation is reduced to about one third as compared with a case where a spatial filter process is performed on a non-interlaced captured image using a normal spatial filter. Can do. Also, considering the case where one frame image is formed with two field images, the amount of calculation can be reduced to about two thirds.

  Next, an imaging system using the imaging apparatus according to the present embodiment will be described.

  FIG. 4 is a schematic configuration diagram of an imaging system using the imaging apparatus according to the present embodiment. As shown in this figure, the imaging system 60 is a system that is installed in a vehicle interior and images the outside of the vehicle through the glass 61, and is applied to, for example, a visual assistance system that provides visual assistance to the driver when the vehicle travels at night. .

  In the imaging system 60, the imaging device 1 is used as an imaging unit for imaging outside the vehicle. The imaging device 1 is installed in the passenger compartment and images the outside of the vehicle through the glass 61. As this imaging device 1, for example, a device having sensitivity to near infrared light is used. By arranging a visible light cut filter in the imaging optical system of the imaging unit 2 of the imaging device 1, it is possible to capture an image centered on the near infrared component. In addition, near infrared light here means light with a wavelength of 780-1500 nm.

  The output side of the imaging device 1 is connected to the system control unit 62. A video signal obtained by photographing with the imaging device 1 is input to the system control unit 62. The system control unit 62 controls the entire system, and includes, for example, a CPU, a ROM, a RAM, an input signal circuit, an output signal circuit, a power supply circuit, and the like.

  The imaging system 60 is provided with a near-infrared projector 63. The near-infrared projector 63 is a light-projecting unit that projects near-infrared light toward the front of the vehicle. The near-infrared projector 63 receives a signal from the system control unit 62 and is controlled to project light. The near-infrared projector 63 is configured to project near-infrared light in an irradiation range corresponding to a high (Hi) beam of a headlight, for example.

  The imaging system 60 is provided with a display unit 64. The display unit 64 is a display unit that displays a captured video of the imaging apparatus 1 and is provided so that the driver can visually recognize the captured video. The imaging system 60 is provided with a switch group 65 for operating on / off of the system.

  Such an imaging system 60 projects near-infrared light in front of the vehicle by the near-infrared projector 63 when the vehicle is traveling at night. Thereby, near-infrared light is irradiated in front of the vehicle, and the vehicle front illuminated with the near-infrared light is photographed by the imaging device 1 having sensitivity in the near-infrared region.

  Then, a video signal is input from the imaging device 1 to the system control unit 62. The system control unit 62 outputs the video signal to the display unit 64, and a captured image based on the video signal is displayed on the display unit 64. The captured image is displayed in a state of being irradiated with near infrared light, so that it becomes easier to detect pedestrians and the like than when the driver of the vehicle visually recognizes the front of the vehicle with the naked eye. Can help. Further, since the light to be projected is near-infrared light, there is little influence on driving the oncoming vehicle.

  Moreover, in this imaging device 1, it is preferable to perform the spatial filter process which removes a predetermined | prescribed low frequency component about a picked-up image. In this case, it is possible to output an image in which the halation around the high luminance portion in the captured image is reduced. Thereby, it is displayed on the display unit 14 in a state in which the halation of the headlight of the oncoming vehicle is reduced, and a pedestrian or the like can be easily visually recognized.

  As described above, according to the imaging apparatus according to the present embodiment, the amount of calculation when performing the spatial filter process by performing the spatial filter process using the spatial filter 40 provided with the thinning line 42 in which the filter coefficient 41 does not exist. Can be reduced. Therefore, the spatial filter process can be performed quickly.

  Further, when the spatial filter 40 performs the spatial filter process on the field image 50 read by the interlace method, the field image 50 is provided by providing the thinning line 52 of the spatial filter 40 corresponding to the blank line 52 of the field image 50. The calculation process in the blank line 52 can be omitted, the calculation amount of the spatial filter process can be reduced, and a quick and smooth image process can be performed.

  Moreover, it is useful as an imaging device that is installed in a vehicle and photographs the outside of the vehicle. In this case, although the shooting environment changes greatly, appropriate shooting can be performed in response to the change in the shooting environment. In particular, when used as a photographing means of a visual assistance system, an appropriate photographed image can be displayed even when the photographing environment changes greatly, which is optimal.

  In the imaging apparatus according to the present embodiment, the image processing is described using the spatial filter 40 in which the thinning line 42 is provided only in the horizontal direction. However, the imaging apparatus according to the present invention is limited to such an imaging apparatus. Instead, as shown in FIG. 5, image processing may be performed using a spatial filter 40 a provided with thinning lines 42 a and 42 b in both the horizontal direction and the vertical direction.

  In this case, if the spatial filter 40a has a size of 5 × 5, the computation amount of the spatial filter processing for the m × n field image is ((m / 2) × (n / 2)) × (3 × 3 ) = 2.3 (m × n). For this reason, the amount of calculation is reduced to about 1/10 compared with the case where non-interlaced mxn size images are subjected to spatial filter processing using a normal 5 × 5 spatial filter without the thinning line 42. can do. Also, considering the case of forming one frame image with two field images, the amount of calculation can be reduced to about one fifth.

  Further, in the present embodiment, the case of applying to the visual assistance system that assists the visual recognition of the driver in the night driving of the vehicle has been described in detail, but the imaging device according to the present invention is not limited to such, The present invention may be applied to other systems such as a road white line recognition system. Moreover, you may apply to what is installed in places other than a vehicle.

1 is a schematic configuration diagram of an imaging apparatus according to an embodiment of the present invention. It is explanatory drawing of the spatial filter used for the image process of the imaging device of FIG. It is explanatory drawing of the field image image-processed in the imaging device of FIG. It is explanatory drawing of the imaging system using the imaging device of FIG. It is explanatory drawing of the spatial filter used for the image process of the imaging device of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Imaging device, 2 ... Imaging part, 3 ... Image processing part, 31 ... A / D conversion part, 32 ... Spatial filter part, 33 ... D / A conversion part, 40 ... Spatial filter, 42 ... Thinning line, 50 ... Field image, 52 ... Blank line.

Claims (8)

Imaging means for receiving and photoelectrically converting incident light from an imaging target;
Image processing means for performing image processing on a captured image output from the imaging means;
Configured with
The image processing means digitizes the captured image to form a digital image in which pixels are arranged vertically and horizontally, and spatially filters the digital image using a spatial filter provided with thinning lines having no filter coefficients;
An imaging apparatus characterized by the above.   The imaging apparatus according to claim 1, wherein the thinning line is provided in a horizontal direction of the spatial filter.   The imaging apparatus according to claim 1, wherein the thinning line is provided in a direction perpendicular to the spatial filter. The imaging means sequentially reads field images in an interlaced manner,
The image processing means performs the spatial filter processing using the spatial filter in which the thinned lines correspond to blank lines in the field image;
The imaging apparatus according to claim 1.   The imaging apparatus according to claim 4, wherein the spatial filter includes the thinning lines extending in the horizontal direction every other line in the vertical direction.   The imaging apparatus according to claim 1, wherein the spatial filter removes a predetermined low-frequency component in the captured image.   The imaging apparatus according to claim 1, wherein the imaging apparatus is mounted on a vehicle and photographs a traveling direction of the vehicle.   The imaging device according to claim 1, wherein the imaging device is used in a visual assistance system that provides visual assistance to a driver when the vehicle travels at night.

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