JP4407475B2 - Camera image processing device - Google Patents

Description

  The present invention relates to a camera image processing apparatus that corrects the luminance of a camera image taken in a low or high illuminance environment.

As a conventional example for improving the image quality of an image captured in a low-light environment such as at night, for example, the following Patent Document 1 proposes a technique for synthesizing one still image from a plurality of continuous still images. Has been
JP 2000-163560 A (Abstract)

  However, the conventional example described above has a problem that a memory for storing a plurality of images is necessary and the circuit cost is high. In addition, since the calculation is performed with data one frame or more before, an appropriate calculation result is not obtained when a scene change occurs in a moving image.

  Therefore, the present invention uses an existing configuration in which a plurality of pixel values in a frame are multiplied by a coefficient to convert the number of pixels, and the brightness of a camera image in a low or high illuminance environment is set to a plurality of images. It is an object of the present invention to provide a camera image processing apparatus that can correct a scene change at a low cost without using the camera and also when a scene change occurs in a moving image.

In order to achieve the above object, the camera image processing apparatus of the present invention provides:
An imaging unit;
An image processing unit that sets a plurality of pixels of an image photographed by the imaging unit as a set, generates an interpolation pixel by multiplying each set of pixels by a predetermined coefficient, and adds them, thereby converting the number of pixels; ,
A first coefficient set in which the sum of the coefficients to be multiplied by each of the set of pixels is 1, a second coefficient set in which the sum of the coefficients is a number less than 1, and a number in which the sum of the coefficients is greater than 1 Bei example and setting means for setting as the predetermined coefficient to the image processing section selectively switched and a third coefficient set to be,
The setting unit receives brightness information of the image from the imaging unit or the image processing unit,
The setting means determines whether the image is brighter than the predetermined luminance or darker than the predetermined luminance based on the luminance information, and selects the third coefficient set when determining that the image is darker than the predetermined luminance. The image processing unit is configured to set the predetermined coefficient .

  According to the present invention, the coefficient of pixel number conversion is changed and corrected using a configuration in which a plurality of pixel values in a frame are multiplied by a coefficient to convert the number of pixels. The brightness of the camera image taken in can be corrected at low cost without using a plurality of images and even when a scene change occurs in a moving image.

  Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of a camera image processing apparatus according to the present invention, FIG. 2 is an explanatory diagram showing pixel number conversion of the camera image processing apparatus in FIG. 1, and FIG. 3 is a camera image processing apparatus in FIG. It is explanatory drawing which shows the coefficient table.

  In FIG. 1, a CCD input unit (including a filter, a timing signal generation circuit, a CPU / I / F circuit, and an I / F circuit with an image processing unit 3) 2 that receives pixel data from the CCD 1 standardizes the pixel signal. The digital video signal is converted into a digital video signal format (Y / C data), and the Y / C data is output to the image processing unit 3. FIG. 1 shows a case in which Cb and Cr multiplexed (MUX) C signal and Y signal are exchanged by two systems. At this time, the Y signal and the C signal may be output separately, may be a Y / C multiplexed signal, or Y, Cb, and Cr may be transferred as separate signals.

  In the image processing unit 3, the Y / C data is first separated into a Y signal and a C signal by a separation unit (DeMUX) 30, and the number of pixels is converted in the H (horizontal) direction by the pixel number conversion units 31 and 32 in the H direction. (Enlargement and reduction), once writing to the work memory 4, and further reading each of them, performing the pixel number conversion in the V (vertical) direction by the pixel number conversion units 33 and 34 in the V direction, and then again in the work memory 4 Convert writing screen size. The converted pixel data is read from the work memory 4, converted into a digital video signal in the digital video signal output unit 5, and then converted into a TV signal such as NTSC / PAL by the video D / A converter 6, and then monitored. 7 is displayed. Alternatively, after reading from the work memory 4, the coding block 8 performs MPEG, JPEG, H.264, etc. H.264, DV, etc. are recorded on a recording medium 9 such as a hard disk, semiconductor memory, DVD, or DVC cassette.

  The above signal flow may be otherwise. For example, the input data from the CCD 1 may be separated by the separation unit (DeMUX) 30 and immediately recorded in the work memory 4 and read again by the pixel number conversion units 31 and 32 in the H direction. Further, first, the pixel number conversion units 33 and 34 in the V direction read out from the work memory 4 to perform processing, and after writing into the work memory 4, the pixel number conversion units 31 and 32 in the H direction read out, and after processing, The data may be output to the next-stage circuit.

FIG. 2 is an explanatory diagram for creating an interpolation pixel as an example when performing pixel number conversion (enlargement or reduction) in the present invention. FIG. 2 shows a case in which the number of pixels is converted in order to enlarge the V direction. In FIG. A case is shown in which a sum-of-products operation is performed on data to newly obtain a pixel at a certain location (between lines n and n + 1 in FIG. 2). In FIG. 2, pixel data is newly created from 6 pixels, but this process may be any number of pixels. In this example, H and V are divided into two times. However, it is possible to create an arbitrary pixel from pixel data in an oblique direction, and in that case, H and V are divided into two times. Alternatively, there may be a method that can be completed once. In FIG. 2, it is shown that the pixel data to be obtained is obtained by the following equation.
Y = 0.05Y (n-2) + 0.10Y (n-1) + 0.35Y (n)
+ 0.35Y (n + 1) + 0.10Y (n + 2) + 0.05Y (n + 3)

  Normally, when creating arbitrary pixel data from multiple pixels, the sum of the coefficients for each pixel component is calculated based on the idea that the luminance component of the completed pixel data should be the same as the original picture. It is set to 1. Note that the coefficient value can be set from the microcomputer (HOST) 10 in the circuit of the present invention. For the setting, the coefficient itself may be set, or it may be set which of a plurality of coefficient combinations is selected as shown in FIG. The coefficient may be determined using a function having the average value of the luminance component as a variable. FIG. 3 shows a coefficient table in the V direction when a combination of a plurality of coefficients is previously stored in the table. “Type 1” indicates a case where the luminance correction is not performed and the total value of the coefficients is 1. “2” indicates a case where the total value of the coefficients is 0.6 for darkening, and “type 3” indicates a case where the total value of the coefficients is 3.0 for brightening.

  The microcomputer 10 in FIG. 1 can set “always increase sensitivity”, “sensitivity decrease”, “sensitivity increase”, and “sensitivity increase function off” in accordance with a low or high illumination imaging environment by the user. When “sensitivity down” is set, “type 2” shown in FIG. 3, “sensitivity up” is set, “type 3”, and “sensitivity up function off” are set The “type 1” coefficient is set in the pixel number conversion units 31 to 34, respectively. Further, the microcomputer 10 receives information on the luminance from the CCD input unit 2, and determines whether the image is bright or dark when “always increase sensitivity” is set. For example, when the average value of luminance in the screen is lower than a certain value, it is determined that the image is darker than a predetermined value, and the “sensitivity increase” process is performed. The luminance information may be obtained from the image processing unit 3. The processing for increasing the sensitivity is only to select “type 3” in the coefficient table shown in FIG. 3, and the luminance component is changed to a large value without adding a special processing time or adding a significant circuit. It is possible. For example, after changing the screen size, changing the luminance component of the screen requires a multiplier and an adder that perform a product-sum operation, which greatly changes the circuit scale. Since the product-sum operation circuit of the pixel number conversion units 31 to 34 is used, the circuit scale does not increase.

  The sensitivity up / down processing may be performed by selecting a coefficient from the table shown in FIG. 3 or by calculating the coefficient itself from the average value of the luminance signal as described above. For example, the coefficient may be obtained by calculation so that the average value of luminance is a certain amount.

According to the present invention,
Since the existing pixel number conversion units 31 to 34 are used, the sensitivity can be increased without increasing the number of logic circuits and memories.
In the case of a moving image, even if a scene change occurs, it can be calculated by the same processing as usual because it is obtained by filter calculation from one frame image.

FIG. 1 is a block diagram showing an embodiment of a camera image processing apparatus according to the present invention. It is explanatory drawing which shows pixel number conversion of the camera image processing apparatus of FIG. It is explanatory drawing which shows the coefficient table of the camera image processing apparatus of FIG.

Explanation of symbols

1 CCD
2 CCD input unit 3 Image processing unit 4 Work memory 5 Digital video signal output unit 6 Video D / A converter 7 Monitor 8 Coding block 9 Recording medium 10 Microcomputer 30 Separation unit (DeMUX)
31-34 Pixel number converter

Claims (1)

An imaging unit;
An image processing unit that sets a plurality of pixels of an image photographed by the imaging unit as a set, generates an interpolation pixel by multiplying each set of pixels by a predetermined coefficient, and adds them, thereby converting the number of pixels; ,
A first coefficient set in which the sum of the coefficients to be multiplied by each of the set of pixels is 1, a second coefficient set in which the sum of the coefficients is a number less than 1, and a number in which the sum of the coefficients is greater than 1 Bei example and setting means for setting as the predetermined coefficient to the image processing section selectively switched and a third coefficient set to be,
The setting unit receives brightness information of the image from the imaging unit or the image processing unit,
The setting means determines whether the image is brighter than the predetermined luminance or darker than the predetermined luminance based on the luminance information, and selects the third coefficient set when determining that the image is darker than the predetermined luminance. A camera image processing apparatus configured to set the image processing unit as the predetermined coefficient .

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