JP2000287200A - Video compressing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the compression ratio of an image by measuring an exposure level in a peripheral part and that in a center part, comparing the output levels of both circuits for measurement, selecting a front light time correcting circuit when the image of the peripheral part is darker than that of the center part or selecting a rear light time correcting circuit when the former is brighter than the latter. SOLUTION: When it is judged that the exposure level measuring signal S122 of the peripheral part is higher than the exposure level measuring signal of the center part, that is, the state is of rear light, the comparison judging signal S126 of a comparing circuit 124 becomes '1' level, the comparison judging signal S124 of the rear light time correcting circuit 125 is selected by a selection switch circuit 127 and outputted to the correction video signal S12 of a preprocessing circuit. Otherwise, when it is judged that the exposure level measuring signal S122 of the peripheral part is lower than that of the center part, that is, the state is of front light, the comparison judging signal S126 becomes '0' level, the correction video signal S125 of the front light time correcting circuit 126 is selected by the circuit 127 and outputted to the correction video signal S12 of the preprocessing circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video compression apparatus, and more particularly to a video compression apparatus which compresses and outputs visitors and background video signals captured by a fixed camera.

[0002]

2. Description of the Related Art Conventionally, there has been an apparatus as shown in FIG. In FIG. 7, the video compression device 3
Comprises a camera unit 31, a video compression circuit 32, and an output circuit 33.

In such a video compression apparatus 3, for example, a video signal S captured and output by a camera unit 31 is output.
Reference numeral 31 denotes a video compression circuit 32, for example, a JPE for each screen.
It is converted into a G format video signal S32, and is output from the output circuit 33 as a video output signal S33 via a terminal T3.

[0004]

Since the conventional video compression transmission apparatus is configured as described above, in a system in which a screen is compressed for each imaging screen, such as a JPEG compression system, a picture is taken by a camera unit. Since the video signal of both the visitor and background information is compressed and output each time, the background information that is unnecessary for identifying the visitor is also compressed and output together. There was a problem of receiving it.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. Before compressing a video signal output from a camera unit, background information on the periphery of a visitor is converted to a white level or a black level in advance. It is an object of the present invention to provide a video compression apparatus in which, by performing pre-fixing processing and then performing video compression, background information unnecessary for identifying a visitor is reduced and a video compression ratio is improved.

[0006]

In order to achieve the above object, a video compression transmission apparatus according to the present invention receives a visitor by inputting an analog video signal output from a camera unit and a camera unit for capturing an image of a visitor with a background. A pre-processing circuit that outputs a digital video signal from which background information of the peripheral part of the user has been removed, and a digital video signal output by the pre-processing circuit is J
A video compression device comprising a video compression circuit for compressing video by a method such as PEG, and an output circuit for outputting an output signal of the video compression circuit to the outside, wherein a preprocessing circuit converts an analog video signal into a digital video signal. A / D conversion circuit, a peripheral exposure circuit for measuring a peripheral exposure level of a digital video signal output from the A / D converter circuit, and a central exposure circuit for measuring a central exposure level And a comparison circuit for comparing the output levels of the peripheral exposure circuit and the central exposure circuit, and if the peripheral image of the digital video signal is darker than the central image, select a correction circuit for direct light, and And a selection switch circuit for selecting a backlight correction circuit when the image is brighter than the image at the center.

In this image compression apparatus, when it is judged by the peripheral exposure circuit of the preprocessing circuit, the central exposure circuit and the comparison circuit that the image of the peripheral part is darker than the image of the central part of the image pickup screen of the camera unit, the light is illuminated. Select the time correction circuit, and if it is judged that the image in the peripheral part is brighter than the image in the center part of the imaging screen of the camera unit, select the backlight correction circuit, and the correction function of the forward light correction circuit or the backlight correction circuit Clarifies the image of the visitor located in the center of the imaging screen,
By compressing the background information located at the periphery of the imaging screen at the white or black level and then compressing it with the video compression circuit, the video compression ratio can be improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a video compression apparatus according to the present invention will be described in detail with reference to the drawings. FIG.
The video compression device 1 comprises a camera unit 11, a preprocessing circuit 12, a video compression circuit 13, and an output circuit 14. The output of the camera unit 11 is connected to the input of the preprocessing circuit 12, and the output of the preprocessing circuit 12 Is the video compression circuit 13
The output of the video compression circuit 13 is connected to the input of the output circuit 14, and the output of the output circuit 14 is connected to the terminal T1.

The pre-processing circuit 12 includes an A / D conversion circuit 12
1. An exposure level measurement signal S122 of a video signal of a peripheral portion of a visitor captured by inputting a digital video signal S121.
Peripheral exposure circuit 122 for measuring and outputting an image, an exposure level measurement signal S123 of a video signal of a central part of the imaged visitor
, A peripheral exposure level measurement signal S122 and a central exposure level measurement signal 123, and a peripheral exposure level measurement signal S122.
Is larger than the central exposure level measurement signal S123, for example, outputs a one-level comparison determination signal S126. If the peripheral exposure level measurement signal S122 is smaller than the central exposure level measurement signal S123, it outputs 0, for example. Comparison circuit 1 that outputs level comparison determination signal S126
24, when the comparison determination signal is at one level, the output signal S124 of the backlight correction circuit 125 is selected, and the comparison circuit 124
When the comparison determination signal S126 output from the A / D conversion circuit 121 is at the 0 level, the selector switch circuit 127 selects the output signal S125 of the correction circuit 126 during forward light and outputs the corrected video signal S12. The input terminal is connected to the video signal output terminal of the camera unit 11, and the A / D
The video signal output terminal of the conversion circuit 121 is the peripheral exposure circuit 1
22, a central exposure circuit 123, a forward light correction circuit 126,
An exposure level output terminal of the peripheral exposure circuit 122 is connected to one of the exposure level input terminals of the comparison circuit 124, and is connected to respective video signal input terminals of the backlight correction circuit 125.
The exposure level output terminal of the central exposure circuit 123 is connected to the other exposure level input terminal of the comparison circuit 124, and the video signal output terminal of the correction circuit 126 during forward light is connected to one video signal input terminal of the selection switch circuit 127. The video signal output terminal of the backlight correction circuit 125 is connected to the other video signal input terminal of the selection switch circuit 127.
The switching control signal output terminal of the comparison circuit 124 is connected to the switching control signal input terminal of the selection switch circuit 127, and the video signal output terminal of the selection switch circuit 127 is connected to the video signal input terminal of the video compression circuit 13.

In such a video compression apparatus 1, for example, an analog video signal S 11 of a visitor imaged by the camera unit 11 is converted to an A / D conversion circuit 1 of a preprocessing circuit 12.
21 and is converted into a digitized video signal S121 and output. FIG. 5 shows an example of the input visitor image. In FIG. 5, it is assumed that the head of the visitor Hu is located at the center of the screen, and the center portion including the head of the visitor Hu is defined as zone Z2, and the peripheral portion is defined as zone Z1. A / D
The video signal S12 digitized by the conversion circuit 121
1 is a peripheral exposure circuit 122 and a central exposure circuit 12
3, the exposure level of the peripheral zone Z1 is measured by the peripheral exposure circuit 122 as, for example, the average value of the zone Z1, and the peripheral exposure level measurement signal S122
Is output as The exposure level of the central zone Z2 is measured by the central exposure circuit 123, for example, as an average value of the zone Z2, and the central exposure level measurement signal S123
Is output as On the other hand, the video signal S121 digitized by the A / D conversion circuit 121 is input to the backlight correction circuit 125 and the forward light correction circuit 126, respectively, and corrected by the characteristics of the correction curve shown in FIG. As shown in FIG. 4A, the camera unit 11 of the video compression device 1 is installed indoors.
Is installed, and when the lighting Li is a so-called downlight that illuminates the area below the ceiling, the image captured by the camera unit is a so-called forward light state in FIG. ). On the other hand, FIG.
As shown in (b), the camera unit 11 of the video compression device 1 is installed outdoors, and the natural light of the sun Sun allows visitors Hu
When the image is captured from the back of the camera Hu, the image captured by the camera unit is a screen shown in FIG. 6A in which the head of the visitor Hu is dark and the background is bright, that is, a backlight state. In the case of FIG. 4B, the video signal S121 input to the backlight correction circuit 125 is a visitor in the backlight state when the input signal level is in the zone of Ia2 in the correction curve of FIG. Is fixed at the white level, and the image of the visitor whose input signal S121 is in the zone of Ia1 is displayed as shown in FIG. 6B so that the image of the visitor becomes clear. Is output as the corrected video signal S124.
On the other hand, in the case of FIG. 4A, the video signal S121 input to the correction circuit 126 at the time of direct light is when the input signal level is in the zone of Ib1 in the correction curve of FIG. In FIG. 6D, the background information of the periphery of the visitor is fixed at a black level, and the image of the visitor whose input signal S121 is in the zone of Ib2 is shown in FIG. The corrected video signal S12 corrected like the screen shown
4 is output. Peripheral exposure level measurement signal S1
In the case of 22, when the exposure level measurement signal at the center is large, that is, when it is determined that the subject is in a backlight state, the comparison determination signal S 126 of the comparison circuit 124 is at one level, and the corrected video signal S 124 of the backlight correction circuit 125 is selected by the selection switch circuit 127. The selected signal is output to the corrected video signal S12 of the preprocessing circuit 12. On the other hand, when the exposure level measurement signal S122 at the peripheral portion is smaller than the exposure level measurement signal at the center portion, that is, when it is determined that the light is in the normal light state, the comparison determination signal S126 of the comparison circuit 124 becomes 0 level, Is selected by the selection switch circuit 127 and is output as the corrected video signal S12 of the preprocessing circuit 12. The video signal S12 corrected by the preprocessing circuit 12 is supplied to the video compression circuit 1
3 and is output as a compressed information signal S13. A compressed video signal S14 is output from a terminal T1 via an output circuit 14. In a video compression system such as the JPEG system, the compression ratio can be increased as the high frequency component of the video signal decreases, so that the background information fixed to the white level or the black level by the preprocessing circuit 12 has the high frequency component. Therefore, the compression ratio of the video signal can be increased.

The video signal of the visitor output from the camera unit is input to a preprocessing circuit for reducing background information by a correction circuit selected based on the visitor and the exposure level of the background. Is input to a video compression circuit that compresses a video signal using a method such as JPEG, so that the video compression ratio can be increased. Further, it is possible to configure a recording device that records a long-time video signal without changing the memory size.

[0012]

As is apparent from the above description, according to the video compression apparatus of the present invention, before compressing the video signal output from the camera unit, the background information of the surrounding area of the visitor is determined in advance by the white level. By performing the video compression after performing the pre-processing to fix the black level, it is possible to provide a video compression device in which unnecessary background information for identifying a visitor is reduced and a video compression ratio is improved. There are effects that the notification distance can be extended and a multi-channel video transmission device can be configured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a video compression device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a preprocessing circuit of the video compression device according to the present invention.

3A and 3B show a correction curve of a pre-processing circuit of the video compression apparatus according to the present invention, wherein FIG. 3A shows a correction curve at the time of backlight and FIG.

FIG. 4 shows an example of use of a video compression device according to the present invention,
(A) shows an example of use indoors, (b) shows an example of use outdoors.

FIG. 5 is a conceptual diagram showing an exposure area of a preprocessing circuit of the video compression device according to the present invention.

6A and 6B show corrected images by a pre-processing circuit of the image compressing device according to the present invention, wherein FIG. 6A is an image of a visitor photographed outdoors, FIG. 6B is a corrected image of an outdoor image, and FIG. The photographed image of the visitor, (d) shows a corrected image of the indoor image.

FIG. 7 is a block diagram showing a conventional video compression device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Image compression apparatus 11 ... Camera unit 12 ... Preprocessing circuit 121 ... A / D conversion circuit 122 ... Peripheral part exposure circuit 123 ... Central part exposure circuit 124 ... Backlight Time correction circuit 125: Correction circuit for forward light 126: Comparison circuit 127: Selection switch circuit 13: Image compression circuit 14: Output circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C022 AA06 AA13 AB19 AB68 AC31 AC42 AC69 5C054 AA02 CB01 CC02 CH02 EA01 EB05 ED11 EJ01 EJ02 FC11 FC12 FE09 FF03 HA18 HA22 5C059 KK00 MA00 SS14 TA17 TA26 TC32 TD03 TD03 TD03 DA01 DA02 DB06

Claims (1)

[Claims] 1. A camera unit (11) for capturing an image of a visitor with a background, an analog video signal output from the camera unit being input, and a digital video signal from which background information of a peripheral portion of the visitor has been removed is output. A pre-processing circuit (12), and a video compression circuit (1) for compressing a digital video signal output from the pre-processing circuit into video according to a method such as JPEG.
3) A video compression device including an output circuit (14) for outputting an output signal of the video compression circuit to the outside, wherein the preprocessing circuit converts an analog video signal into a digital video signal. / D conversion circuit (121)
A peripheral exposure circuit (122) for measuring the peripheral exposure level of the digital video signal output from the / D conversion circuit
And a central exposure circuit (1) for measuring the central exposure level.
23) a comparator circuit (124) for comparing the output levels of the peripheral exposure circuit and the central exposure circuit; and correction of the forward light when the peripheral image of the digital video signal is darker than the central image. If the circuit (126) is selected, and the peripheral image is brighter than the central image, the backlight correction circuit (1
25. A video compression device comprising: a selection switch circuit (127) for selecting (25).