JP3635969B2 - TV intercom - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a television interphone that can capture the face and figure of a monitoring target such as a visitor or the like with an imaging camera in a general house or an apartment house, and can check with a monitor installed in the house.
[0002]
[Prior art]
In a conventional television interphone, the slave unit is provided with imaging means such as an electronic shutter or a CCD camera having an automatic gain control (AGC) function, and feedback control is performed so that the average luminance of the screen is constant. As a result, even if the illumination state for imaging the subject changes, it is possible to take an image so that the video to be monitored displayed on the monitor is not crushed white or black.
[0003]
[Problems to be solved by the invention]
However, in the conventional TV intercom, control is performed based on the average luminance of the entire screen. Thus, for example, if a person in front of the image pickup means opposite the light state as the background stood, because a large proportion of the area occupied by the background in the screen, the luminance level of the background is dominant as the average luminance, the luminance level Therefore, the brightness level of the face and body of the visitor to be monitored is relatively lowered and darkened, resulting in poor visibility.
[0004]
The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to confirm a person imaged by an imaging camera of a slave unit without deteriorating visibility on the monitor of the master unit. It is to provide a TV intercom that makes it possible.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided an imaging means for imaging a monitoring target such as a visitor, a light projecting means for irradiating light toward the monitoring target, and turning on / off the light projecting means when the monitoring target is imaged by the imaging means. The lighting control means for performing the control so that the light is turned on during the same period as the imaging period and then turned off during the same period as the immediately following imaging period. An image memory / difference means for storing the recorded video and performing difference processing, and photometry means for calculating the luminance level of the area obtained by the difference processing, and feeding back the obtained luminance level to the imaging means to obtain the difference area Is composed of a slave unit that corrects an image to be captured at a desired luminance level, and a master unit that displays a feedback-controlled image to be monitored on a monitor.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a television intercom according to an embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a schematic configuration diagram of a television intercom. FIG. 2 is an explanatory diagram showing temporal changes in the photometric signal and the infrared light emitting diode signal. FIGS. 3A and 3B are explanatory views showing a process of extracting a target region. FIG. 3A shows an image before processing, FIG. 3B shows an image when an infrared light emitting diode is turned on, and FIG. An image when the outer light emitting diode is turned off is shown, (d) shows the extracted region of interest (person area), and (e) shows an image whose luminance is controlled in the person area.
[0007]
In the television intercom 1 according to the present embodiment, the deterioration of the visibility that has occurred because the average luminance of the entire screen is used for the control of the screen brightness, and the attention site (for example, the face and body of the customer) ) So that the region of interest can be monitored with appropriate luminance at all times.
[0008]
In a conventional TV door phone, a light projecting means (for example, an infrared light emitting diode) is turned on to illuminate a visitor at a relatively short distance (assuming about 50 cm from the camera) in order to solve the shortage of illumination at night. However, in the television door phone of the present embodiment, the region of interest is extracted using the reflected light. Specifically, the infrared light-emitting diode is turned on for a certain frame period, and the infrared light-emitting diode is turned off in the next one frame. A pair of images is obtained and a region of interest is extracted from the comparison.
[0009]
As shown in FIG. 1, the television intercom 1 according to the present embodiment includes a slave unit 3, a signal transmission system 5 that transmits an image signal, and a master unit 7 that has a monitor (not shown) that displays an image. Consists of.
[0010]
The slave unit includes an imaging unit 31 such as a CCD camera, a synchronization signal generating unit 32 that supplies a synchronization signal to the imaging unit 31, and an infrared light emitting diode (corresponding to a light projecting unit for illuminating a visitor at night or the like). Infrared LED) 33, synchronous lighting control means 34 for controlling the lighting of the infrared light emitting diode 33 in accordance with the synchronizing signal, and video signals from the imaging means 31 are digitized and stored, and the infrared light emitting diode 33 is turned on. An image memory / difference unit 35 that performs a difference process from the video signal at the time and when the light is turned off, a photometric unit 36 that calculates a luminance level of the video signal according to the output, and a feedback of the photometric level to the imaging unit 31. And a multiplexing means 37 that multiplexes an audio signal or the like generated by a visitor to the video signal and sends it to the master unit 7 via the signal transmission system 5.
[0011]
The synchronization signal generating means 32 is self-running and generates a synchronization signal for the imaging means 31. This synchronization signal is supplied to the imaging means 31 and also to the synchronous lighting control means 34. The synchronous lighting control means 34 creates a photometric signal for extracting a site of interest. As shown in FIG. 2, the synchronous lighting control means 34 generates a photometric signal over a period of two frames, of which the infrared light emitting diode 33 is lit during one frame period, and the next one frame is infrared. The light emitting diode 33 is controlled to be turned off, and the photometric means 36 is notified that it is a photometric period. This photometry is performed periodically when the TV door phone 1 starts displaying video or during video display.
[0012]
As shown in FIG. 2, since one frame is composed of two fields, the photometric signal two frame periods are four field periods. In the present embodiment, although the duration of the on / off respectively by one frame, on / off period is not limited thereto, conveniently it is also possible to field processing of half .
[0013]
The image pickup means 31 used here is a fixed image pickup device such as a CCD camera, generates a video signal in synchronization with an external synchronization signal, and receives an external input to perform feedback control, thereby performing an electronic shutter. Or performing automatic gain control (AGC) to control the luminance in imaging.
[0014]
The image memory / difference unit 35 digitizes the video signal from the video unit 31 and stores one frame, performs a difference with the next one frame, and compares an image with a large difference by comparing with a predetermined threshold value. Output “1” and others as “0”. This binarized image is input as a photometric pattern to the photometric means 36 at the next stage. When the photometric means 36 digitizes the video signal and receives the above-mentioned photometric pattern during the photometric period from the synchronous lighting control means 34, the photometric means 36 accumulates the video signal data of the pixel “1” and “1”. From the sum of the number of pixels for one screen, the average luminance of the region of interest is calculated, and the information is fed back to the imaging means 31. Thereby, in the imaging means 31, control is performed so that the brightness | luminance of an attention site | part becomes appropriate (for example, median value).
[0015]
The processing described above will be described with reference to FIG. FIG. 3A shows an image before processing. As shown in this image, in the TV door phone 1, the brightness of the background is high when the person is standing in front of the child unit 3, when the sun is present in the background, or when the background is irradiated with sunlight. In many cases, the brightness of the face is very high. In such a case, in the normal image pickup means 31, since the bright background is dominant, the face of the customer is often blacked out due to the lack of the dynamic range.
[0016]
For such an image, in the television door phone 1 according to the present embodiment, the infrared light emitting diode 33 blinks in units of frames, and the attention area is extracted. FIG. 3B is an example of an image when the infrared light emitting diode 33 is turned off, and a person's region is dark as in FIG. Next, a difference process is performed on the images when the infrared light emitting diodes 33 are turned on and off as shown in FIGS. 3B and 3C, and binarization is performed using a preset threshold value. As a result, it is possible to extract a site of interest (person area) as shown in FIG. Of course, strictly speaking, since the reflectance of the face, clothes, etc. is not constant in the human region, it is actually difficult to completely extract all desired regions as shown in FIG. However, it is possible to extract a region of a target region that is generally desired. The average brightness of only the extracted region is calculated by the photometry means 36 and fed back to the image pickup means 31 to appropriately control the brightness of the region of interest, that is, the person as shown in FIG. It will be done. In the control described above, a bright background (bright sky clouds or sun) may cause whitening. However, in view of the purpose of the TV door phone 1, even if it becomes difficult to see a bright background such as the sky, it is considered that it does not cause a problem in use.
[0017]
In the above description, it is assumed that the background is brighter than the person. Conversely, even when the background is dark and the person is bright, the brightness of the reflected light of the infrared light emitting diode 33 is high. It goes without saying that a similar control function can be realized as long as a difference occurs.
[0018]
Further, here, the infrared light emitting diode 33 is used for extracting the attention site, but this is because the infrared light emitting diode 33 is mounted on the general television door phone 1 and no additional light projecting means is added. This is because the light source other than the infrared light emitting diode 33 may be used because it can be easily diverted to the extraction of the region of interest.
[0019]
Further, although the external synchronization type that operates in synchronization with an external synchronization signal is used as the imaging means 31 here, even if the internal synchronization type that generates the synchronization signal itself and operates at that timing, the synchronization means Any signal can be used if it is output to the outside. In this case, since the synchronization signal from the imaging unit 31 is directly input to the synchronous lighting control unit 34, the synchronization signal generating unit 32 is not necessary and a simple configuration can be achieved.
[0020]
【The invention's effect】
As described above, according to the first aspect of the present invention, the imaging means for imaging a monitoring target such as a visitor, the light projecting means for irradiating light toward the monitoring target, and the imaging target at the time of imaging the monitoring target A lighting control unit that performs lighting / extinguishing control of the light projecting unit so that the light projecting unit is turned on in the same period as the predetermined period of imaging and then is turned off in the same period as the predetermined period of imaging immediately after An image memory / difference means for storing the video imaged by the imaging means at the time and when the light is turned off and performing a difference process; and a photometry means for calculating the brightness level of the area obtained by the difference process; Since it is composed of a slave unit that feeds back to the imaging means and corrects the difference area so that it is imaged at a desired luminance level, and a master unit that displays the feedback-controlled image to be monitored on the monitor. hand In view of the fact that the brightness changes due to flashing is mainly a monitoring target such as a visitor, an image of the monitoring target is extracted as a target region, and feedback control is performed on the imaging means based on the luminance level of the monitoring target Therefore, it is possible to provide a TV interphone that can confirm a person imaged by an imaging camera of a slave unit on a monitor of the master unit without deteriorating the visibility.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a television interphone.
FIG. 2 is an explanatory diagram showing temporal changes in a photometric signal and an infrared light-emitting diode signal.
FIGS. 3A and 3B are explanatory diagrams showing a process of extracting a target region, where FIG. 3A shows an image before processing, FIG. 3B shows an image when an infrared light emitting diode is turned on, and FIG. An image when the infrared light emitting diode is turned off is shown, (d) shows the extracted region of interest (person area), and (e) shows an image whose luminance is controlled in the person area.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 TV intercom 3 Slave unit 5 Signal transmission means 7 Master unit 31 Imaging means 32 Synchronization signal generation means 33 Infrared light emitting diode (light projection means)
34 Synchronous lighting control means 35 Image memory / difference means 36 Photometric means 37 Multiplexing means

Claims (1)

An imaging unit for imaging the monitored such visitor, a light projecting means for irradiating light toward the monitored control of the ON / OFF of the light projection means monitored during imaging by the imaging means, and a predetermined period of imaging A lighting control means for turning on the light during the same period and then turning it off during the same period as the predetermined imaging immediately after that, and storing and calculating the difference between the images taken by the imaging means when the light projecting means is turned on and off An image memory / difference means for performing the above and a photometry means for calculating the luminance level of the area obtained by the difference processing, and the difference area is imaged at a desired luminance level by feeding back the obtained luminance level to the imaging means. A television interphone comprising: a sub-unit that corrects the image to be monitored; and a parent unit that displays a feedback-controlled image to be monitored on a monitor.

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