JPH07177407A - Image pickup device - Google Patents

Abstract

PURPOSE:To effectively edge-correct images whose resolution feeling is degraded in the case of obtaining high magnification images by emphasizing the edge part of the images by a variable difference circuit, varying a difference width corresponding to a magnification rate and varying the characteristics of an emphasizing processing. CONSTITUTION:Video images optically inputted from a lens 1 are turned to electric signals by a CCD2, a signal processing is performed in an image pickup signal processing circuit 3 and analog signals are outputted. The output of the circuit 3 is AD converted in an ADC4 and written in the address of a frame memory 5 specified by a write address controller 10. Then, a read address controller 11 is controlled by a tele/wide changeover switch 12 and a magnification generator 13 and read from the address specified by the read address controller 11 is performed. For read data, inter-pixel data are interpolated in an interpolation circuit 6, the emphasizing processing of an edge is performed in an edge emphasizing processing circuit 7, DA conversion is performed in a DAC8 and recording is performed by a recording circuit 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device such as a camcorder having an electronic zoom function.

[0002]

2. Description of the Related Art A conventional electronic zoom has been developed in which an image pickup signal is once written in a frame memory, the timing of reading from the frame memory is changed, and the read image pickup signal is supplemented with interpolation data to electronically enlarge a taken image. Has been done.

[0003]

However, when the image is magnified by using the electronic zoom in the image pickup apparatus, the sampling frequency becomes low, so that the horizontal and vertical resolutions are deteriorated, and the image has a low resolution. In order to enhance the resolution, there is a method of mounting a high-definition CCD and a high-magnification lens, but this is not practical because the cost is high and the volume is large.

[0004]

A video signal is written to an address of a frame memory designated by a write address controller, data is read from a frame memory address designated by a read address controller at a timing different from a write timing, and a variable difference is read. An edge enhancement processing circuit including a circuit enhances the edge portion of the image by the video signal, and changes the difference width according to the enlargement ratio to change the characteristics of the enhancement processing.

Further, the difference value is determined from the input data of the difference circuit and the weighted sum of the two kinds of delay data according to the enlargement ratio, and the characteristic of the emphasis process is changed.

Further, it is characterized in that the degree of emphasis processing is changed according to the enlargement ratio.

[0007]

FIG. 1 shows an embodiment of the present invention.

Reference numeral 1 is a lens having an image pickup lens, diaphragm and filter, 2 is a CCD as an image pickup device, 3 is an image pickup signal processing circuit having a gamma correction / low pass filter / clip circuit, 4 is an AD converter (ADC), and 5 is A frame memory, 6 is an interpolation circuit for interpolating data between pixels of an image, 7 is an edge enhancement processing circuit for performing edge enhancement of an image,
Reference numeral 8 is a DA converter (DAC), and 9 is a recording circuit for recording an image pickup signal of a VTR or the like. Reference numeral 10 is a write address controller for designating a write address of the frame memory 5, reference numeral 11 is a read address controller for designating a read address of the frame memory, 12 is a tele / wide changeover switch, and 13 is a magnification generator.

The image optically input from the lens 1 is
It becomes an electric signal by the CCD 2. Imaging signal processing circuit 3
The signal is processed by and an analog signal is output. The output of the image pickup signal processing circuit 3 is AD-converted by the ADC 4 and written to the address of the frame memory 5 designated by the write address controller 10. Next, the read / address switch 11 and the magnification generator 13 control the read address controller 11 to read from the address specified by the read address controller 11. Interpolated data is interpolated by the interpolating circuit 6 in the read data, edges are emphasized by the edge emphasizing processing circuit 7, DA converted by the DAC 8, and recorded by the recording circuit 9.

FIG. 2 is a detailed diagram of the edge enhancement processing circuit 7.

Reference numeral 101 is a variable difference circuit 1, 102 is a variable difference circuit 2, 103 is a correction amount calculation circuit, 104 is an adder,
Reference numeral 105 is a delay circuit.

When a video signal is input in FIG. 2, the variable difference circuit 1 (10) is supplied in accordance with the magnification signal at that time.
1), the variable difference circuit 2 (102) detects the edge by calculating the second difference of the input signal, the correction amount calculation circuit (103) determines the correction amount, and the adder (104) determines the delay circuit ( In step 105), edge processing is performed by adding the output signal to the video signal with the adjusted output timing.

FIG. 3 shows the first part of the variable difference circuit 1 (101).
It is an example of.

Reference numerals 201 to 4 are registers, 205 is a comparator, 206 is a decoder, 207 is a selector, and 208 is a subtractor.

In FIG. 3, the comparator (205),
The magnification signal is converted into an integer in the decoder (206), and the delay time of the video signal is determined by the selector (207). Then, the difference from the input video signal is calculated.
Note that FIG. 3 shows an example in which a 4 × electronic zoom is used, and the number of stages in the register is determined according to the zoom magnification. If the electronic zoom has a high magnification, the number of register stages can be increased, and if the magnification is low, the number of register stages can be decreased.

FIG. 4 is an explanatory diagram of the output of the difference circuit 1 (101).

The current image, doubled image, variable differential circuit 1 output thereof, quadruple image, difference variable circuit 1 output thereof, but the output value of the variable differential circuit 1 in the case of double and its part in the image The output values of the variable difference circuit 1 are four times the same. The same method is used in the difference circuit 2 (102). If the difference values are made equal in this way, the edge correction amount for each edge does not change even if the magnification changes.

FIG. 5 is a detailed diagram of an embodiment of the correction amount calculation circuit (103).

Reference numeral 301 is a base clip circuit, 302 is an output inverting circuit, 303 is a correction coefficient generator 1, and 304 is a multiplier.

The second-order difference signal of the video signal is input to the correction amount calculation circuit (103). In the multiplier (304), the input signal is base clipped by the base clip circuit (301), and the output inversion circuit (302) outputs a signal which is positive and negative inverted, and which is calculated by the correction coefficient generator (303). Multiply and output. In the adder (104), the edge is emphasized by adding the output of the correction amount calculation circuit (103) to the video signal.

FIG. 6 shows a second embodiment of the variable difference circuit (101).

As in the case of FIG. 3, a 4 × magnifying circuit is used for the description. In FIG. 6, reference numerals 401 to 4 denote registers, and 405 ...
406 is a selector, 407 and 408 are multipliers, 409 is an adder, 410 is a subtractor, and 411 is a coefficient / switching signal generator.

FIG. 7 shows a coefficient / switching signal generator (41
It is a detailed view of 1).

In FIG. 7, 501 is a comparator, 5
Reference numeral 02 is a decoder, and 503 and 504 are subtractors.

In FIG. 7, when a magnification signal is input, the comparator (501) and the decoder (502) use an integer signal as a switching signal, and a subtractor (503) outputs the magnification signal and the decoder (502) output. Coefficient k due to the difference
2 is output, and the difference between 1 and the output of the subtractor (503) is calculated from the subtractor (504), and the coefficient k1 is output.

FIG. 8 is an explanatory diagram of the coefficients k1 and k2 and the switching signal.

When the magnification signal changes within the range of 1 to 4, the switching signal according to the difference width is determined. When the magnification signal increases, the coefficient k2 increases in the range of 0 to 1, and when the switching signal changes, the coefficient k2 is set to 0. On the contrary, the coefficient k1 decreases in the range of 1 to 0 when the magnification signal increases, and the coefficient k1 is set to 1 when the switching signal changes.

FIG. 9 is a detailed diagram of the edge emphasizing circuit 7 according to the third embodiment of the present invention.

Reference numeral 601 denotes a variable difference circuit 1 similar to 101,
602 is a variable difference circuit 2 similar to 102, 603 is a base clip circuit, 604 is an output inverting circuit, 605 is a correction coefficient generating circuit 2 having a magnification signal as an input, 606 is a multiplier, and 607 is an adder. .

In FIG. 9, after calculating the second-order difference by the method of the first and second embodiments of the present invention, the base clip circuit (60
3) Base clip and output inversion circuit (604)
The output of the correction coefficient generator (605), which is variable according to the magnification signal, is added to the output inverted by the multiplier (60).
6) and the input video signal is multiplied by an adder (60
By adding in 7), an edge correction signal is output. For example, if the correction coefficient output from the correction coefficient generator 2 (605) is set to increase in response to an increase in the magnification signal, the resolution of a high-magnification image obtained by electronic zoom deteriorates. It is possible to perform cooperative edge correction on the image.

[0031]

As described above, according to the present invention, compared to an image magnified by electronic zoom in a conventional image pickup apparatus, a high-quality image with less deterioration of the image can be provided without mounting a high-definition CCD. Since a signal is obtained, a low-cost and high-performance imaging device can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a detailed diagram of an edge enhancement processing circuit 7 in the embodiment of the present invention.

FIG. 3 shows a variable difference circuit 1 (1
The figure which shows the 1st Example of (01).

FIG. 4 is an operation explanatory diagram of FIG. 3;

FIG. 5 shows a correction amount calculation circuit (1
Detailed view of 04).

FIG. 6 shows a variable difference circuit 1 (1
The figure which shows the 2nd Example of (01).

7 is a coefficient / switching signal generator (411) in FIG. 6;
Detailed view of.

FIG. 8 is an operation explanatory diagram of the coefficients k1 and k2 and the switching signal of FIG.

FIG. 9 is a detailed diagram of a third embodiment (edge emphasis circuit 7).

Claims (1)

[Claims] 1. An enlarging means for writing a video signal to an address of a frame memory designated by a write address controller, and reading data from an address of a frame memory designated by a read address controller at a timing different from the timing of writing, by the video signal. An edge emphasis processing circuit including a variable difference means for emphasizing an edge portion of an image, and a control means for changing the difference width of the variable difference means according to the image enlargement ratio by the enlargement means and changing the characteristic of the emphasis processing. Imaging device.