JP2007067714A - Image processing circuit, and camera device and vehicle-mounted camera device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To digitally correct the image distortion and then encode to improve the image quality. <P>SOLUTION: The image processor circuit has a means for digitally processing brightness signals of an input image, a means for digitally processing color signals of the input image, a means 130 for correcting the distortion of the image as being fed with the brightness signals and color signals processed by the brightness signal processing means and the color signal processing means, and an encoder 143 for generating analog composite picture signals from brightness signals and color signals outputted from the distortion correcting means. This corrects the image distortion before encoding, thus improving the image quality. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image processing circuit using a solid-state imaging device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), a camera device using the image processing circuit, and an in-vehicle camera device. Processed in the module (device) to obtain high resolution, low cost and high reliability image quality.

In a vehicle-mounted camera (device) equipped with a camera module, two cameras are required to capture both left and right images for a blind corner. In order to improve this, recently, a method for displaying both left and right images on a vehicle-mounted camera device via a prism has been disclosed in Japanese Patent Laid-Open No. 2001-219783. However, the number of pixels of the solid-state imaging device constituting the camera module may be as small as 250,000 pixels, and there is a problem with the resolution of the image, or the application is limited because the camera device captures an image through a prism. There have been problems such as an increase in the external size.
Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-297405) discloses an imaging device (imaging system) that enables imaging of the front and left and right sides of a vehicle with a single camera device. A wide-angle lens and a prism are combined, and the image sensor is moved by a linear motor device so that a suitable image can be displayed according to the traveling state of the vehicle.
However, the use of a motor complicates the control, and since it has a mechanical drive unit, high reliability is required and high cost and an increase in shape (size) are inevitable.
Japanese Patent Application Laid-Open No. 2001-219783 JP 2004-297405 A JP 2004-80545 A

Conventionally, the problem that the distortion correction processing unit could not be built in the camera signal processing LSI is that the circuit scale becomes too large in the existing distortion correction method.
On the other hand, Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-80545) discloses that an image can be reduced to an appropriate circuit scale while maintaining the image quality by devising an algorithm and an architecture.
In addition, the reason why the conventional technique is difficult to solve is that the video transmission of the in-vehicle camera uses the NTSC (National Television System Committee) method, and the video output (NTSC signal) from the conventional in-vehicle camera device is a subsequent processing block. After AD (Analog / Digital) conversion, digital signal processing is used to correct distortion, and DA (Digital / Analog) conversion is converted to NTSC analog signal and displayed on LCD (Liquid Crystal Display) monitor. It was that.
In the processing as described above, since the distortion correction is performed after the analog signal is once converted into the NTSC system, the image quality deteriorates due to the band limitation of the NTSC signal. Further, there is a problem that image quality deteriorates by repeating AD conversion and DA conversion.

  The present invention has been made in view of the above problems, and its purpose is to correct the distortion of an image (or video) in a camera device in order to output a high-quality, high-resolution video, An image processing circuit that does not cause image degradation due to the band limitation of the NTSC signal described above by converting the distortion-corrected image (video) into a NTSC system after digital processing by a processing device outside the camera (device). Another object of the present invention is to provide a camera device and an in-vehicle camera device using the same.

The image processing circuit of the present invention includes a luminance signal processing means for digitally processing a luminance signal of an input image, a color signal processing means for digitally processing a color signal of the input image, and the luminance signal processing means and the color signal processing means. The image processing apparatus includes a distortion correction unit that receives signal-processed luminance signals and color signals and corrects image distortion, and an encoder that generates an analog composite video signal from the luminance signals and color signals output from the distortion correction unit.
The image processing circuit of the present invention includes a luminance signal processing means for digitally processing a luminance signal of an input image, a color signal processing means for digitally processing a color signal of the input image, and the luminance signal processing means and the color signal processing means. Signal processing luminance signals and color signals are supplied, image distortion correction is performed, and distortion-corrected digital luminance signals and color signals are output to subsequent signal processing means.
The camera device of the present invention includes a wide-angle lens, a sensor to which an image light signal is input via the wide-angle lens, and a distortion of the converted input image after converting the image signal output from the sensor into a digital signal. An image processing circuit for correction and an encoder for encoding a distortion-corrected digital image signal into a video transmission signal are included.
An in-vehicle camera device of the present invention has a wide-angle lens, converts an optical signal input through the wide-angle lens into an electrical signal by a light receiving element, generates an image signal, and performs image processing on the input image of the image signal After the distortion is corrected by a circuit and encoded into a video transmission signal, the video transmission signal is output.

An image processing circuit according to the present invention, and a camera device and an in-vehicle camera device using the same realize high image quality and are provided outside the camera device and are ECUs (Electrical) that are processing blocks connected to the output of the camera device. The load on the control unit (electronic control unit) can be reduced. By performing image distortion correction using a DSP (Digital Signal Processor) in the camera apparatus, the viewpoint of the image can be converted, and the distortion-corrected image from the camera apparatus is synthesized to provide a bird's eye view. Etc. can be output.
Conventionally, the output from the camera device is transmitted as an analog signal of the NTSC system, etc., and after AD conversion is performed by a processing unit (ECU) in the subsequent stage, the distortion of the camera device is corrected as a digital signal, and further DA conversion is performed to analog signal It was converted to NTSC system. The image quality deteriorated due to the band limitation of the NTSC signal and repeated AD conversion and DA conversion for the image data, but the image quality was improved by digitally correcting the image distortion inside the camera device. .
Since distortion correction data can be stored in advance in the memory inside the camera device, it is not necessary to perform command communication, and the mode can be changed to a desired mode by selecting an external terminal of the DSP. For example, modes such as selection of an image cutout location, zoom range, viewpoint conversion, and PAN / TILT operation can be selected by an external terminal. Of course, the mode can be changed by communication.
Further, since the output of the camera device is added to the analog signal output and also adapted to the digital signal output, it can be adapted to various digital processing.

FIG. 1 shows a block configuration of a camera device (module) 10 according to an embodiment.
The camera device (module) 10 includes, for example, a wide angle lens 11, a sensor (light receiving element) 12, and a camera signal processing unit 20.
The camera signal processing unit 20 includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a camera signal processing circuit 23, a distortion correction circuit 24, an NTSC encoder 25, and the like.
For example, as a vehicle-mounted camera device, a plurality of camera devices (modules) 10 shown in FIG. 1 are mounted, and can be arbitrarily provided at the front, left, right, or rear of the vehicle as required.
The (camera) signal processing circuit 23 of the camera signal processing unit 20 includes a pre-processing unit having a CDS (correlated double sampling) and a preamplifier, an A / D (analog / digital) converter, a correction processing unit (circuit), a luminance It consists of a signal processing unit and a color signal processing unit.

The wide-angle lens 11 projects an image (light signal) of a subject (not shown) on the imaging surface of the sensor 12. At this time, when the viewing angle is 180 degrees, for example, distortion occurs in the peripheral portion of the image. Therefore, it is necessary to correct.
The sensor 12 is composed of, for example, a CCD, a CMOS, etc., and is composed of multiple pixels such as 1.3 million pixels with respect to the conventional 250,000 pixels. The sensor 12 converts the image light signal transmitted through the wide-angle lens 11 into an electrical signal, and outputs the image signal. Is supplied to a camera signal processing circuit 23 having a CDS (correlated double sampling), a preamplifier and the like.
By increasing the number of pixels in the sensor 12, the image quality is not deteriorated even if a partial area of the image is enlarged, and a high resolution is obtained when the enlarged display after distortion correction of the peripheral portion of the image is obtained. Can be maintained.
The distortion correction circuit 24 is a digital signal processed by the camera signal processing circuit 23 and output. The Y (luminance) signal digital data (hereinafter referred to as luminance (Y) data) and chroma (C; color) signal digital. Data (hereinafter referred to as color (C) data) is supplied, and signal processing for real-time image distortion correction is performed. The description regarding this operation will be described later.
The Y data and C (color) data output from the distortion correction circuit 24 are input to, for example, the NTSC encoder 25, and an analog composite signal or component signal combined with the synchronization signal is output.
In addition, the Y data and C data of the digital signal are directly output from the distortion correction circuit 24 so that the digital signal can be processed in the subsequent stage.
Further, since distortion correction data can be stored in advance in the memory inside the camera device (10), it is not necessary to perform command communication, and a desired mode can be set by selecting an external terminal of the digital signal processing device (DSP). Transition is possible. Since the camera device (10) includes a CPU, it is of course possible to perform command communication using this CPU.

FIG. 2 shows a block configuration of an ECU (Electrical Control Unit) 50. The ECU 50 is provided outside the camera device (module) 10 and is connected to an output terminal of the camera device 10. For example, in the case of an in-vehicle camera device (system), the camera device 10 is provided at the front of the vehicle, connected to an ECU 50 provided in the vehicle via a cable or the like, and an image processed by the ECU 50 is displayed via a monitor. ing.
The ECU 50 includes a camera interface 51, an image ASIC 52, a CPU 54, an image memory 55, a data memory 56, a monitor interface 53, and the like.
The camera interface 51 is connected to the output of the camera device 10 described above, and can also be connected to the outputs of a plurality of camera devices (camera 1 to camera N) (not shown), and a plurality of image signals can be taken in arbitrarily. .
In the case of a digital signal, digital data is supplied to the input terminal of the camera interface 51 from the digital I / F 145 of the camera post-processing unit 140 shown in FIG. 2, and in the case of an analog signal, the analog signal is output from the D / A converter 144. The analog composite signal converted into is supplied.
Then, the images from the cameras (devices) 1,..., Camera N are switched, or a plurality of images are arbitrarily selected and output to the subsequent image ASIC 52.
When image processing is performed by the image ASIC 52, image data is stored in the image memory 55 under the control of the CPU 54, the stored image data or other data is read, and data is written to or read from the data memory 56. The image ASIC 52 uses these data under the control of the CPU 54 to perform image processing such as image segmentation, composition, and superimposition of character information.
For example, when image data from the camera 1 selected from the cameras (devices) 1,..., Camera N is input to the image ASIC 52 via the camera interface 51, the CPU 54 converts the input image data. The image data is stored in the image memory 55, and the character data or graphic data is read from the image memory and the data memory 56 and synthesized. As a specific example, an image captured by a camera device provided at the rear of the vehicle is subjected to distortion correction by the camera signal processing unit 20 and stored in the image memory 55. ) The locus data and the character information are synthesized by the image ASIC 52 and displayed on the monitor in front of the vehicle via the monitor interface 53. Therefore, the backward direction of the vehicle can be confirmed by a display image of a monitor provided in the vehicle, which can contribute to safe driving of the vehicle.

FIG. 3 shows a detailed block diagram regarding the camera signal processing unit 20 (100).
The camera signal processing unit 100 includes a camera preprocessing unit 110, a distortion correction unit (circuit) 130, a camera postprocessing unit 140, a synchronization separation unit 150, a clock generation circuit 161, a CPU 162, and the like.
Here, the distortion correction unit 130 is configured in front of the frequency conversion circuit 141 of the camera post-processing unit 140, but it may be in the rear, and the connection position is not limited to the configuration in FIG.

The pixel signal output from the sensor 12 is sampled and held to extract a necessary pixel signal. The pixel signal is subjected to gain control (AGC) to be adjusted to an appropriate level and supplied to the A / D converter. .
An A / D converter (not shown) has a 10 to 12-bit accuracy to handle pixel signals, converts an analog signal to a digital signal, and outputs the digital signal to the camera preprocessing unit 110 at the subsequent stage.

  The camera preprocessing unit 110 includes a preprocessing unit including a digital AGC (Automatic Gain Control) 111, a shading correction 112, a pixel defect correction 113, an optical black level detection 114, and a Y-LPF (luminance signal). Luminance signal processing unit comprising a low-pass filter / clamp 115, contour correction 116, and gamma (γ) correction 117, C-LPF (chroma low-pass filter) / clamp (processing unit) 118, RGB Matrix (RGB matrix) 119 , A white balance (WB) / gamma (γ) correction 120, a hue / gain adjustment 121, and a color signal processing unit 122 constituted by a Cr / Cb (color difference signal) generation (circuit) 122, and digital Signal processing is performed. Hereinafter, a digital signal handled by each processing unit is simply referred to as data.

In the preprocessing unit, optical black level detection, digital gain control (digital gain control), shading correction generated in the wide-angle lens 11 and pixel defect correction are performed using a delay line.
Luminance signal processing unit performs Y (luminance) signal vertical / horizontal (direction) contour correction (VH aperture control), Y luminance signal and vertical / horizontal contour correction signal Mix (mixing; addition) processing, γ (gamma) correction, etc. Various image processing is performed.
The color signal processing unit includes color separation and clamping processing, removal of color signal noise and color false signals, RGB matrix (Matrix) processing, white balance (WB) adjustment for varying coefficients of R, G, and B colors, γ (Gamma) correction, RG / BG conversion, color false signal suppression processing, Hue / Gain adjustment, color difference signal (Cr / Cb) generation, and the like are performed.
Further, the CPU 162 controls the white balance adjustment, Hue / Gain adjustment, gamma correction setting of the camera preprocessing unit 110, the image clipping region of the distortion correction circuit 130, the memory control and the analog composite signal output of the camera postprocessing unit 140. Switching of digital RGB signal (etc.) output, frequency setting for frequency conversion, and the like are controlled via buses (B1 to B7).
The CPU 162 supplies a control signal to the distortion correction circuit 130 to cut out an arbitrary area of the image whose distortion is corrected in addition to controlling the distortion correction of the normal image, and zooms the arbitrary area to process the enlarged image. Generate distortion so that distortion can be corrected. Further, after being taken in by a wide-angle lens, the PAN / TILT processing can be processed electronically based on the distortion-corrected image. The CPU 162 performs UART communication and exchanges data with a memory (EEPROM) and a sensor I / F through input / output terminals.

FIG. 3 shows a block configuration of a camera preprocessing unit 110, a distortion correction circuit 130, and a camera postprocessing unit 140, which are embodiments of the present invention. In the camera pre-processing unit 110, an optical black level (OB) detector 114 uses the data (ADout) output from the A / D converter to calculate the black level of the input data (signal) and clamps it. Outputs data for level calculation.
An adder (not shown) subtracts the black level from the input data (ADout) to generate new pixel data based on the black level (clamped to the black level).
The digital gain adjustment (AGC) 111 adjusts the brightness by digitally changing the level of the data clamped at the black level output from the adder.
In the shading correction 112, there is a luminance difference (unevenness) in the peripheral portion with respect to the central portion of the image due to the aperture of the wide-angle lens 11, and this unevenness in luminance is corrected.
The defect correction 113 uses a delay line and a calculator (adder / subtracter), for example, delays input data, obtains an average value before and after the defective pixel using the delayed pixel value, and replaces it with the defective pixel. Thus, pixel defect correction is performed.

  The data corrected by the defect correction 113 and further separated into the luminance signal and the color signal are supplied to the luminance signal processing unit (Y-block) and the color signal processing unit (C-block), respectively.

In the luminance signal processing unit (Y-block), the Y-LPF / clamp 115 performs addition arithmetic processing on the luminance data to equivalently remove noise. Further, the black level of the luminance data is clamped to a predetermined level.
A contour correction (vertical / horizontal contour correction; VH aperture control) 116 uses a delay element and an arithmetic unit for addition / subtraction processing to generate a pulse for emphasizing a horizontal contour portion of the image, and also in the vertical direction of the image. A pulse for emphasizing the contour portion of is also generated.
A contour correction adder (not shown) supplies the horizontal contour correction pulse and the vertical contour correction pulse output from the vertical / horizontal contour correction (116) and the luminance data supplied from the Y-LPF (115). Then, the luminance data with the contour enhanced is output by the addition process.
For example, when the display device is a CRT (Cathode Ray Tube), the gamma (γ) correction 117 is 2.2 on the imaging side in advance since the γ characteristic of the CRT is 2.2. The curve of the output characteristic is corrected so that the gradation of the image is correctly reproduced on the CRT side so that a correct reproduced image can be obtained. The gamma-corrected luminance data (Y) is output to the subsequent distortion correction circuit 130.

Next, the color signal processing unit (C-block) will be described.
The color signal processing unit includes a color (chroma) signal low-pass filter (C-LPF) / clamp 118, RGB Matrix (RGB matrix) 119, white balance (WB) adjustment / gamma (γ) correction 120, Hue (hue control) / A gain (gain) adjustment 121, a Cr / Cb generation (circuit) 122, and the like are included.
The image signal (data) output from the defect correction 113 is supplied to the C-LPF / clamp 118 of the color signal processing unit.
The chroma signal low-pass filter (C-LPF) of the C-LPF / clamp 118 is constituted by a digital low-pass filter, for example, and removes false color signals and noise from the color-separated signals. The color data is clamped to a predetermined value by a clamp (118).
The RGB Matrix (RGB matrix) 119 calculates the output data from the C-LPF / clamp 118 to obtain R, G, and B primary color data, and outputs them to the white balance (WB) adjustment / γ correction 120.
In the white balance (WB) adjustment (120), the R (red), G (green), and B (blue) color signals (data) are multiplied by a predetermined coefficient to set the white color for the target color temperature. ing. The color data with white balance is output to gamma correction (120), where it is converted into input / output characteristics according to the display device.
The hue / gain adjustment 121 adjusts color data by changing the hue and the gain.
The Cr / Cb generation 122 generates RY and BY color difference signals from the color data whose hue and gain are adjusted by the Hue / Gain 121. Here, Cr = R−Y, Cb = B−Y (Y is a luminance signal). This color difference signal (C) is output to the distortion correction circuit 130 at the next stage.

When the color data is input to the color signal processing unit, the C-LPF / clamp 118 removes frequency components in a higher frequency range than the color data, and removes noise and color false signals.
Color data from which noise and color false signals have been removed is obtained as R, G, B three primary color signals by the RGB matrix 119, white balance is adjusted by white balance (WB) adjustment / γ correction 120, and gamma correction (120). To correct the gamma (γ) for the color signal. The data output from the white balance (WB) adjustment (120) is output to a color signal optical detector (not shown), where the level of the color data is detected. The detected color data is supplied to AE (automatic exposure) / AWB (automatic white balance adjustment) (not shown), and the color temperature for the color signal (data) is obtained by software processing using a computer or a computing device. The correction coefficient of each color with respect to the (white) color temperature is calculated, and the data is fed back to the white balance (WB) adjustment (120) to automatically adjust the white balance.

The white balance adjusted color data is gamma-corrected and further subjected to Hue / Gain adjustment. Next, an RG / BG conversion circuit (not shown) converts RG / BG from the R, G, B color data, and suppresses the color false signal. Then, using the RG and BG data generated by the RG / BG conversion in the Cr / Cb generation 122, the color data of the color difference signal of Cr = RY and Cb = BY is generated. To do.
Luminance Y data is
Y = 0.30R + 0.59G + 0.11B (1)
It is expressed as
Cr = R−Y = 0.70 (RG) −0.11 (B−G) (2)
Cb = B−Y = 0.89 (B−G) −0.30 (R−G) (3)
And can be transformed. That is, the Cr and Cb color difference signals can be obtained from the equations (2) and (3) using the RG and BG color data. The color difference signal is output to the distortion correction circuit 130 together with the luminance signal Y.

Next, FIG. 4 shows a block configuration of the distortion correction circuit 130 of FIG.
The distortion correction circuit 200 includes a horizontal direction conversion circuit 201, a vertical direction conversion circuit 202, an image memory (field memory) 203 for horizontal processing, a distortion correction parameter decoder 205, a distortion correction parameter encoder 206, and an image memory (FIFO) for vertical processing. ; Phifo memory) 204, vertical distortion correction parameter decoder 207, vertical distortion correction parameter encoder 208, and the like.
The horizontal direction conversion circuit 201 is connected in series to a data writing unit (not shown), a data acquisition unit, a complementary phase / input data coordinate calculation unit, a correction coefficient generation unit, a data interpolation calculation unit, a line memory, and an output node of the line memory. And a multiplication circuit that multiplies the data output from each register by a corresponding interpolation coefficient, and an addition circuit that adds the data obtained by the multiplication circuit.
The image data input to the horizontal direction conversion circuit 201 is written into an image memory (field memory) 203 together with a write control signal.
By supplying the read control signal to the image memory 203 for horizontal processing, the image data arranged in the horizontal direction is converted into the interpolation data according to the correction parameter (Xm) for the x direction supplied from the distortion correction parameter decoder 205. Acquired as (image data before correction).
Then, a horizontal one-dimensional interpolation calculation is executed using the interpolation coefficient supplied from the interpolation coefficient generation unit, and the calculation result is stored in the image memory 204.
An image memory (field memory) 203 is supplied with input pixels composed of luminance data and color data via a horizontal direction conversion circuit 201, and is used to correct horizontal distortion.
An image memory (FIFO memory) 204 is supplied with image data that has been subjected to distortion correction in the horizontal direction, and is used by the vertical direction conversion circuit 202 to perform distortion correction calculation. The image memory 204 needs to have a capacity capable of storing data over the minimum number of lines necessary for correcting vertical distortion, and also according to the frequency of the output synchronization signal supplied to the buffer capacity provided in the subsequent stage. Determined.

The distortion correction parameter decoder 205 (207) determines a grid necessary for reading the correction parameters to the horizontal direction conversion circuit 201, and normalizes the coordinates supplied from the horizontal direction conversion circuit 201 according to the grid. Using this lattice, the correction vector supplied from the distortion correction parameter encoder 206 is supplied to the horizontal direction conversion circuit 201 (vertical direction conversion circuit 202).
The distortion correction parameter encoder 206 (208) calculates in advance a correction vector corresponding to each position of all pixels from data relating to the distortion aberration of the wide-angle lens 11.
In addition, lattice lines for dividing the correction vectors of all pixel points for each section are determined. The grid division method includes an equal division method that divides a predetermined region equally in the x direction and the y direction, a power division method that divides each grid so that the width of each grid is a power of 2, and division at an optimal division position. There is an optimal division method. In addition, a grid division method is designated from the user interface and a grid division number is designated, and the display image is divided into a designated division number according to the designated division method.
The vertical direction conversion circuit 202, the distortion correction parameter decoder 207, and the distortion correction parameter encoder 208 have the same functions as those in the horizontal direction.

The operation of the distortion correction circuit 200 will be described.
The image data input to the horizontal direction conversion circuit 201 is supplied to the image memory (field memory) 203 together with the write control signal by the data write control unit of the horizontal direction conversion circuit 201, and is supplied to the image memory 203 in accordance with the write control signal. Written.
At this time, the data acquisition unit of the horizontal direction conversion circuit 201 supplies the read control signal to the image memory 203 for horizontal processing, whereby the correction amount parameter (Xm) for x direction supplied from the distortion correction parameter decoder 205 is obtained. In response, image data arranged in the horizontal direction is acquired from the image memory 203 as interpolation data (image data before correction).
Then, the data interpolation calculation unit of the horizontal direction conversion circuit 201 executes horizontal one-dimensional interpolation calculation using the interpolation coefficient supplied from the interpolation coefficient generation unit, and the vertical processing image is input via the vertical direction conversion circuit 202. The calculation result is stored in the memory 204.
For example, in the corrected image, the correction amount parameter Xm of the data located at the point where the x coordinate is 2.0 is set to 1.25. As a result, the x coordinate of the corresponding point of the point in the image before correction is obtained as 3.25 by adding the correction amount parameter Xm to 2.0. At this time, the integer component (3) of the x coordinate (3.25) indicates the address of the data in the image before correction, and 0.25 indicates the interpolation phase. Therefore, the luminance signal at the point where the x coordinate is 2.0 in the image after correction is for a plurality of continuous data having x addresses near 3 in the image before correction, and the phase of the horizontal interpolation filter is 0.25. It is obtained by the one-dimensional interpolation operation.

Next, in the vertical direction conversion unit 202, the data acquisition unit in the vertical direction from the image memory (FIFO memory) 204 for vertical processing according to the correction amount parameter Ym for y direction supplied from the distortion correction parameter decoder 207. The aligned image data is acquired as interpolation data (image data before correction). Then, the vertical one-dimensional interpolation calculation is executed using the interpolation coefficient supplied from the interpolation coefficient generation unit, and the calculation result is output according to the output synchronization signal via the output data buffer.
As described above, the interpolation calculation executed by the horizontal direction conversion circuit 201 and the vertical direction conversion circuit 202 is realized by a simple circuit for one-dimensional interpolation calculation. Since the calculation by can be easily realized, a higher quality image can be obtained.

That is, a distortion correction circuit that corrects an original image having distortion uses a horizontal correction parameter that indicates a horizontal correction amount at a pixel point constituting the original image in the horizontal distortion correction, and performs one-dimensional processing on the original image. By performing an interpolation operation, the distortion in the horizontal direction of the original image is corrected.
In addition, the vertical distortion correction uses an image obtained by horizontal distortion correction, and performs a one-dimensional interpolation operation using a vertical correction parameter indicating a vertical correction amount at a pixel point constituting the original image. The distortion in the vertical direction of the original image was corrected.
Therefore, since the distortion correction circuit performs one-dimensional interpolation calculation in the horizontal direction of the original image in horizontal distortion correction, and the vertical correction means performs one-dimensional interpolation calculation in the vertical direction of the original image, it is possible to reduce the cost in real time. The distortion of the original image can be corrected.

  In the above description, the embodiment in which the one-dimensional interpolation calculation in the vertical direction is executed after the one-dimensional interpolation calculation in the horizontal direction has been described. Conversely, the one-dimensional interpolation calculation in the vertical direction is executed first, Thereafter, one-dimensional interpolation calculation in the horizontal direction may be executed.

3 includes a frequency conversion circuit 141, a filter (Filter) 142, a digital encoder 143, a D / A (digital / analog) converter 144, a digital I / F (interface) 145, and the like. It is configured.
The frequency conversion circuit 141 converts the operation clock used for signal processing in the distortion correction circuit 130 or the like into an operation clock for a video signal in the subsequent stage. For example, in the case of an NTSC signal, the operation clock used for the arithmetic processing operation in the distortion correction circuit 130 is converted to 4 fsc (clock frequency that is four times the chroma frequency), and the same clock frequency as the image processing in the subsequent stage is set to a system such as an ECU. To adapt to.
Since the filter 142 has changed (lowered) the frequency by the frequency conversion circuit 141, the filter 142 removes harmonic components generated at that time.
The digital encoder 143 uses, for example, luminance data and color data (color difference signal) and adds a synchronization signal or the like to generate an NTSC digital composite signal, for example. Of course, you may encode into the video signal of a PAL and SECAM system.
A D / A (digital / analog) converter 144 converts a digital composite signal into an analog composite signal, and is connected to an analog display device so as to display an image.
The digital I / F (interface) 145 outputs digital R, G, B data and the like, and performs an interface for performing digital signal processing and the like in the subsequent stage.
When luminance data and color data whose distortion has been corrected is supplied to the post-processing unit, post-processing for outputting to the ECU is performed using the clock frequency set by the CPU 162.

Next, the operation of the camera post-processing unit will be described. When a control signal (or data) is supplied from the CPU 162 to the frequency conversion circuit 141 via the buses B7, B1, B6, etc., input image data (Y, C data) is driven according to the control signal (or data). The (clock) frequency is set, and the input luminance data and color data are driven by the newly set clock. For example, harmonics other than the basic clock frequency generated by converting the frequency of the image data become interference waves to the system and adversely affect the system.
Digital luminance data and color data are arithmetically processed by the digital encoder 143 to generate a composite digital signal to which a synchronizing signal or the like is added, converted to an analog signal by the D / A converter 144, and output to, for example, a subsequent ECU . The digital luminance data and color data output from the filter 142 are digital R (red), G (green), B (blue) data and other digital signals Y / Cr / through the digital I / F (interface). Cb (ITU-RBT656 / 601 standard format) is output.

Next, an in-vehicle camera device (system) 300 as another embodiment is shown in FIG.
5A includes a camera (device) 1 on the front (front) of a vehicle 301, cameras 2 and 3 on the left and right, and a camera 4 on the rear (rear).
The output of the camera (device) 1 is connected to the input of the camera interface 501 of the ECU 302 (50) provided inside the vehicle 301, for example, in front of the driver's seat, and the other cameras 2 to 4 are similarly connected to the camera of the ECU 302. Connected to the interface 501.
The camera (device) 1 to the camera 4 have the configuration shown in FIG. 1, for example, and use a wide-angle lens 11 to capture a video (image) with a viewing angle of 180 degrees, for example, and correct image distortion caused by the wide-angle lens 11. And output to the ECU 302.
The image capturing angle of the camera (device) 1 provided at the front of the vehicle 301 is in a range indicated by a, and the peripheral portion of the image is distorted because of the wide angle. Similarly, the camera 2 captures images in the range b, the camera 3 captures images in the range c, and the camera 4 captures images in the range of angles d, and outputs these captured images to the ECU 302. As a result, 360 degrees (omnidirectional) images of the front, left, and rear of the vehicle 301 can be captured in the ECU 302. Since the wide-angle lens 11 is used, it is not necessary to mechanically drive a (narrow-angle) lens or a prism to move or rotate the lens.
Since each of the cameras (devices) 1 to 4 has a built-in distortion correction circuit as described above, it is possible to obtain an image when the peripheral area of the image is corrected and viewed normally. The distortion-corrected images are transferred to the ECU 302, and these images are selected as necessary or synthesized using all of these images. Then, the synthesized image is displayed on a monitor in the vehicle.

FIG. 5B shows an example in which images taken by the cameras (devices) 1 to 4 are displayed on a monitor in the vehicle. The corrected image 1 in FIG. 5B corresponds to the image photographed by the camera 1 shown in FIG. 5A, displays a corrected image in which image distortion by the wide-angle lens 11 is corrected, and so on. 2 corresponds to the corrected image 2, the camera 3 corresponds to the corrected image 3, and the camera 4 corresponds to the corrected image 4.
As described above, the omnidirectional image can be confirmed by generating a so-called bird's-eye view that displays the omnidirectional image at a time as if viewed from the front, with the vehicle 301 as a reference, and the peripheral portion of the conventional image. Can be distorted and difficult to see. Further, since the distortion correction circuit is built in each camera (device) 1 to camera 4 and is not configured in the ECU 302 outside the camera device, the ECU circuit configuration can be simplified, and the cost can be reduced accordingly. it can.

FIG. 6 shows another embodiment. Conventionally, the front (left front, right front) of the vehicle is displayed using two camera devices or using a prism in one camera device. On the other hand, FIG. 6 shows an example in which one camera device having a wide-angle lens and a distortion correction circuit is provided at the front of the vehicle as described above.
FIG. 6A schematically shows an image taken by the camera device before distortion correction. Since a wide-angle lens is used, the left and right peripheral areas e and f of the image surrounded by the broken line are distorted. An example in which the image distortion is corrected by the distortion correction circuit of the signal processing unit provided in the camera device for the areas e and f, the respective images are extracted, and synthesized or separately displayed by the ECU is shown in FIGS. ).
In this way, the left and right front of the vehicle can be displayed as if they were viewed straight from one camera device. Further, even if a partial area of a photographed image is enlarged and displayed by using a sensor 12 having a large number of pixels, for example, 1.3 million pixels, the image quality does not deteriorate if the number of pixels is large. As a result, it is possible to make it easier to see a region that has been difficult to see.

FIG. 7 shows an in-vehicle camera device as another embodiment.
In the in-vehicle camera device of FIG. 7, one camera device is installed on the left (right) side of the vehicle, and the camera (device) has a zoom mechanism and a distortion correction function.
FIG. 7A shows an image captured from a wide-angle lens without zooming. The left peripheral part (rear; left rear) and front (left front) images in FIG. 7A are distorted, and the shape of the vehicle as the object is displayed small. FIG. 7B is a diagram in which a wide-angle lens is used to zoom in the rear (left rear) direction to enlarge the position of the vehicle in the left peripheral portion and the image is corrected for distortion. Similarly, FIG. 7C is a diagram in which a part of an image captured by zooming in on the front left side (front) of the vehicle is corrected for distortion.
The image that is small in the rear direction and difficult to see in the left peripheral portion in FIG. 7A is displayed as an enlarged and further corrected image distortion shown in FIG. 7B. For this reason, the distance between the object and the distance can be grasped more accurately than the image before zooming.
Further, as shown in FIG. 7C, the front left part of the vehicle is large, and an image without distortion can be obtained, so that the object can be grasped more accurately, and the distance between the vehicle and the object is obtained. Can be grasped more accurately than in the past.
Thus, by providing the camera with a wide-angle lens and a zoom mechanism and with image distortion correction, for example, when mounted on a vehicle, the front and rear of the vehicle can be accurately imaged with a single camera.

FIG. 8 shows an example of an in-vehicle camera device that is another embodiment.
An example of an image when a wide-angle lens and a camera device having a distortion correction processing function are attached to the rear of the vehicle is shown. FIG. 8A shows an example of distortion correction (conversion) of a rear image of a vehicle photographed by a camera device. In contrast, FIG. 8B shows an image when the viewpoint is converted by distortion conversion of the rear image.
As shown in FIG. 8B, an image viewed from an arbitrary direction can be obtained by converting the viewpoint of the image during the image distortion correction processing. As a result, the driver's recognition for the back can be enhanced with one camera device.

FIG. 9 shows another embodiment. FIG. 9 shows an entire image obtained by correcting an image photographed with a wide-angle lens with a distortion correction circuit in a camera device (system) having a wide-angle lens and an image distortion correction circuit.
A part N1 of the image is displayed for a predetermined time, then the area N2 is displayed for a predetermined time, and finally the area Nn is displayed. PAN (rotation) operation can be smoothly performed electronically by adjusting the display units N1 and N2, N2 and N3,..., Nn-1 and Nn, and the display time of each display unit. it can. Similarly, the TILT (tilt) operation can be electronically performed in the vertical direction.

  Furthermore, in a field of a conventional surveillance camera device or the like as another embodiment, if a camera device having a wide-angle lens and a distortion correction function is used, distortion of an image photographed at a wide angle can be corrected and output. Further, even if a wide-angle lens is used, the image is corrected and displayed on the monitor, so that it is not necessary to mechanically drive the camera device such as rotating and moving, thereby reducing the cost.

As described above, the image processing circuit of the present invention, the camera device using the same, and the in-vehicle camera device can realize high image quality and reduce the load on the ECU that is a processing block at the rear stage of the camera device. Distortion correction is performed by a DSP (digital signal processing device) of the camera device to display an image obtained by converting the viewpoint of the image, and distortion correction images output from a plurality of camera devices are arbitrarily taken in by an ECU outside the camera device. A composite image such as a bird's-eye view can be displayed.
Conventionally, the output from the camera device is transmitted as an analog signal of the NTSC system, etc., AD conversion is performed by a processing unit (ECU section) in the subsequent stage, and then distortion of the image is corrected as a digital signal, and further DA conversion is performed to the NTSC system. Because of the conversion, the NTSC signal has a band limitation and the image is deteriorated by repeating AD conversion and DA conversion. However, the present invention provides high image quality by correcting the image distortion inside the camera device and digitally. Realized.
Since distortion correction data can be stored in advance in the memory inside the camera device, it is not necessary to perform command communication, and the mode can be changed to a desired mode by selecting an external terminal of the DSP.
In addition to the analog signal output, the camera (device) output is also compatible with a digital signal output, so that it can be applied to various digital processing areas.

It is the figure which showed the block structure of the camera apparatus. It is the figure which showed the block configuration of ECU (electronic control unit). It is the figure which showed the block configuration of the camera signal processing part. It is the figure which showed the block structure of the distortion correction circuit. It is a bird's-eye view of an imaging range when a camera device is mounted on a vehicle, and a correction image. It is the figure which corrected the image distortion of the vehicle-mounted camera apparatus. It is the figure which corrected the image distortion of the other vehicle-mounted camera apparatus. It is the figure which corrected the image distortion of the other vehicle-mounted camera apparatus. It is a figure for demonstrating the electronic pan operation | movement and tilt operation | movement of a camera apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Camera apparatus, 11 ... Wide angle lens, 12 ... Sensor (light receiving element), 20 ... Camera signal processing part, 23, 100 ... Camera signal processing circuit, 24, 130, 200 ... Distortion correction circuit, 25 ... NTSC encoder, 50 ... ECU (Electronic Control Unit), 51 ... Camera Interface, 52 ... Image ASIC, 53 ... Monitor Interface, 55, 203, 204 ... Image Memory, 56 ... Data Memory, 110 ... Camera Preprocessing Unit, 111 ... Digital AGC (Gain) Adjustment), 112 ... Shading correction, 113 ... Defect correction, 114 ... Black level detection, 115 ... Luminance signal low-pass filter (Y-LPF) / clamp, 116 ... Outline correction, 117 ... Gamma ([gamma]) correction, 118 ... C- LPF / clamp processing unit, 119 ... RGB matrix, 120 ... whis Balance (WB) adjustment / γ correction, 121 ... Hue / Gain adjustment, 122 ... Cr / Cb (color difference signal) generation (circuit), 201 ... horizontal direction conversion circuit, 202 ... vertical direction conversion circuit, 205,207 ... distortion Correction parameter decoder, 206, 208 ... distortion correction parameter encoder.

Claims (17)

Luminance signal processing means for digitally processing the luminance signal of the input image;
Color signal processing means for digitally processing the color signal of the input image;
Distortion correction means for supplying a luminance signal and a color signal subjected to signal processing by the luminance signal processing means and the color signal processing means, and correcting distortion of the image,
An image processing circuit comprising: an encoder that generates an analog composite video signal from a luminance signal and a color signal output from the distortion correction means.   The distortion correction means performs a one-dimensional interpolation operation on the input image using a horizontal correction parameter indicating a horizontal correction amount at pixel points constituting the input image, thereby correcting the distortion of the input image in the horizontal direction. The image obtained by the correction is subjected to a one-dimensional interpolation operation using a vertical correction parameter indicating a correction amount in a vertical direction at a pixel point constituting the input image. The image processing circuit according to claim 1, wherein distortion in a direction is corrected.   The image processing circuit according to claim 1, wherein the distortion correction unit performs distortion correction of the input image by changing a viewpoint during distortion correction processing. Luminance signal processing means for digitally processing the luminance signal of the input image;
Color signal processing means for digitally processing the color signal of the input image;
The luminance signal and the color signal subjected to the signal processing by the luminance signal processing means and the color signal processing means are supplied, the distortion of the image is corrected, and the distortion-corrected digital luminance signal and the color signal are output to the subsequent signal processing means. And an image processing circuit.   The distortion correction means performs a one-dimensional interpolation operation on the input image using a horizontal correction parameter indicating a horizontal correction amount at pixel points constituting the input image, thereby correcting the distortion of the input image in the horizontal direction. The image obtained by the correction is subjected to a one-dimensional interpolation operation using a vertical correction parameter indicating a correction amount in a vertical direction at a pixel point constituting the input image. The image processing circuit according to claim 4, wherein distortion in the direction is corrected.   The image processing circuit according to claim 4, wherein the distortion correction unit performs distortion correction of the input image by changing a viewpoint during distortion correction processing. A wide-angle lens,
A sensor to which an image light signal is input via the wide-angle lens;
An image processing circuit that corrects distortion of the converted input image after converting the image signal output from the sensor into a digital signal;
An encoder that encodes a distortion-corrected digital image signal into a video transmission signal.   The image processing circuit includes a distortion correction unit, and performs a one-dimensional interpolation operation on the input image by using a horizontal correction parameter indicating a horizontal correction amount at a pixel point constituting the input image. Correcting the distortion in the horizontal direction of the image, and subjecting the image obtained by the correction to a one-dimensional interpolation operation using a vertical correction parameter indicating the correction amount in the vertical direction at the pixel points constituting the input original image The camera apparatus according to claim 7, wherein distortion in the vertical direction of the input image is corrected.   The camera apparatus according to claim 8, wherein the distortion correction unit performs distortion correction of the input image by changing a viewpoint during distortion correction processing.   The camera device according to claim 7, wherein the camera device electronically moves an arbitrary area of the distortion-corrected image left and right or up and down to generate a left and right or up and down rotation image.   An image signal is generated by converting a light signal input through the wide-angle lens into an electric signal by a light receiving element, and generating an image signal, and correcting an input image of the image signal by an image processing circuit. An in-vehicle camera device in which a camera device that outputs the video transmission signal after being encoded in the vehicle is mounted on the vehicle.   The in-vehicle camera device according to claim 11, wherein the camera device is provided in at least one of front, rear, left and right parts of a vehicle, and an output of the camera device is supplied to an electronic control unit to perform image processing after distortion correction processing. .   The in-vehicle camera device according to claim 11, wherein the image processing circuit of the camera device includes a storage device that stores a plurality of distortion correction data, and the processing mode is changed by selecting a control terminal of the image enlargement processing circuit.   The image processing circuit includes a distortion correction unit, and performs a one-dimensional interpolation operation on the input image by using a horizontal correction parameter indicating a horizontal correction amount at a pixel point constituting the input image. By correcting distortion in the horizontal direction of the image, and performing a one-dimensional interpolation operation on the image obtained by the correction using a vertical correction parameter indicating a vertical correction amount at a pixel point constituting the input image The in-vehicle camera device according to claim 11, wherein distortion in the vertical direction of the input image is corrected.   The in-vehicle camera device according to claim 14, wherein the distortion correction unit performs distortion correction of the input image by changing a viewpoint during distortion correction processing.   The in-vehicle camera device according to claim 11, wherein the light receiving element includes a plurality of pixels, and prevents deterioration in resolution of a cut-out image or a zoomed image.   The in-vehicle camera device according to claim 12, wherein the electronic control unit synthesizes distortion-corrected images output from the plurality of camera devices.

Images