JPH0530512A - Visual interphone - Google Patents

Abstract

PURPOSE:To form a TV interphone generating no graphic distortion even at the time of picking up an image at a wide angle by previously setting up correction data for correcting distortion due to a wide angle lens in an address table, correcting the distortion by means of the correction data and then writing data in accordance with the address corrected by means of the correction data. CONSTITUTION:When it is supposed that a current address generated by an address generator 23 is included in a picture element of X=1FH and Y=2H and correction data of X=-3H and Y=+1H are obtained by inputting the address in an address table 24, the values of the correction data are respectively added to the current address, a correction address consisting of X=1 and Y=3H is generated and the image data of the current address X=1FH, Y=2H are stored in a picture element corresponding to the corrected address X=1CH, Y=3H in an image memory 22. When said scanning is executed in the whole image and data are read out by normal laster scanning, a read image has no distortion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television intercom capable of capturing a visitor's face or the like with a television camera and monitoring it inside a house at the entrance or gate of a general household.

[0002]

2. Description of the Related Art Conventionally, this type of TV intercom has been
It consists of a slave unit with a built-in TV camera installed at the entrance, gate, etc. of a general household, and a master unit installed inside the house with a built-in monitor, and images the visitors standing in front of the entrance with a TV camera. The video signal is sent to the parent device, and the family member confirms the visitor.

In such a TV intercom, in order to capture an image of a visitor standing in front of the front door on the monitor, a mechanical function of adjusting the viewing angle is added, but after fixing the field of view once. In order to capture an image with a fixed field of view, it was not possible to capture the image of the visitor accurately when the position or height of the visitor changed.

Therefore, there is a method in which the image pickup lens of the television camera is wide-angled to have a wide field of view so that the entire image can be picked up. There was a problem of being visible.

In order to solve such a problem, a wide-angle imaging lens is used, the imaging field of view is set wide in advance, and the distortion of the wide-angle lens is measured in advance in order to correct the generated graphic distortion. A method is conceivable in which the address is converted into a corrected address corresponding to the scanning address 1: 1.

[0006]

However, in order to realize this, an address table for address conversion may be used. For example, the image size is 512 × 512.
, Then this table is (9+
9) It is necessary to have 18 bits of corrected address data, that is, 512 × 512 × 18 =
There is a problem that the capacity of 4718592 bits is required, and the cost of the ROM for the address table becomes high.

The present invention has been made in view of the above points, and an object thereof is to use a wide-angle lens or the like as an image pickup means without using a large-capacity address table. It is to provide a TV intercom that does not cause graphic distortion even when the image is captured.

[0008]

According to a first aspect of the present invention, an image pickup means for picking up an image of a visitor or the like and a slave unit having a video output circuit for outputting a video signal from the image pickup means to a transmission line are provided. A / D conversion means for digitizing a video signal transmitted via a transmission line, an image memory for storing image data digitized by the A / D conversion means, and D for image data read from the image memory / A to convert D /
In a television interphone including an A conversion unit and a master unit having a monitor for displaying an analog image signal output from the D / A conversion unit on a screen, a video signal transmitted from a slave unit to a video signal of the image memory. An address generating means for generating an address, an address table for outputting correction data for address correction based on the generated address, and an address generating means for generating a corrected address from the correction data are added. The image data is written in the image memory by the generated address.

Further, in claim 2, an address latch for holding the corrected address is added, and the address generating means generates a corrected address from the address held in the address latch and the correction data. It is characterized by doing so.

[0010]

In the television intercom of the present invention, when the image data obtained by A / D converting the video signal from the slave unit is written in the image memory, the correction data for correcting the distortion due to the wide-angle lens is provided. The address table is set in advance and the correction data is used to write according to the corrected address.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. Reference numeral 1 denotes a child device installed at the entrance, gate, etc. of a general home, which images a visitor and outputs a video signal thereof.

The slave unit 1 is an image pickup unit 11 including a television camera for picking up an image of a visitor, and a video output circuit for transmitting a video signal output from the image pickup unit 11 from the slave unit 1 to a master unit 2 described later. Comprising 12.

The video output circuit 12 includes a balancing circuit when the video signal and the power supply are superimposed by using a simple pair line such as a telephone line as a transmission line.

The image pickup means 11 is preferably a CCD image pickup device from the viewpoints of cost and stability, and a wide-angle lens is used as an image pickup lens so that a visitor stands in front of the child device 1 in height and the like. Make sure that the field of view is set to a wide angle so that the variation in can be absorbed.

Generally, the figure distortion caused by the lens is as shown in FIG.
When a plurality of rectangles as shown in (a) are imaged by a wide-angle lens, small graphic distortion occurs in the central part and large graphic distortion occurs in the peripheral part, as shown in FIG. 2 (b).

This distortion increases as the lens has a wider angle. Reference numeral 3 is a transmission line composed of a coaxial cable or a telephone line, and transmits the video signal output from the slave unit 1 to the master unit 2.

Reference numeral 2 denotes a parent device installed in the house, which takes in a video signal input from the child device 1 via the transmission line 3 and monitors the video.

The master device 2 includes an A / D converter 21, an image memory 22, an address generator 23, and an address table 2.
4, X address generating means 25, Y address generating means 2
6, D / A conversion means 27 and a monitor 28 are included.

The video signal from the child device 1 is input to the A / D conversion means 21 and, for example, 1 according to the sampling signal.
It is converted into 8-bit digital image data per pixel.

On the other hand, the video signal from the slave unit 1 is also input to the address generating means 23, and the address generating means 23 separates the sync signal from the video signal, and the raster for the image memory synchronized with the sync signal. An X address in the X axis direction and a Y address in the Y axis direction are generated.

The X address and the Y address are input to an address table 24 composed of a ROM or the like, and the correction address data ΔX and ΔY preset by the address table 24 for correcting the graphic distortion by the wide-angle lens are obtained. Given.

The corrected address data ΔX and ΔY are X
The address generating means 25 and the Y address generating means 26 add to the X address and the Y address to obtain desired corrected address data X ′, Y ′.

The image data output from the A / D conversion means 21 is stored in the image memory 22 according to the address data X'and Y '.

The size of the image memory is, for example, 512 ×
It is 512 or 256 × 256.

The digital image stored in the image memory 22 is read out, converted into an analog image signal by the D / A conversion means 27, and displayed on the screen by the monitor 28.

Next, the operation of this embodiment will be described with reference to FIG. First, the distortion of the image due to the wide-angle lens used is measured in advance, and the correspondence (mapping) of the address between the distorted image and the corrected image is obtained.

That is, it is necessary to find out which point the address of each pixel of the distorted image should correspond to in order to correct it.

This correspondence can be found by calculation if the spatial transfer function of the wide-angle lens to be used is known, but if the spatial transfer function is not known, it is shown in FIG. Image a pattern or grid pattern as shown, specify how some characteristic points such as corner points or grid points should be corrected, and then interpolate other points from these points. Just ask.

The correction data thus obtained is written in the address table 24 in advance.

Now, as shown in FIG. 3, the current address generated by the address generating means 23 is X = 1FH, Y.
= 2H (H indicates a hexadecimal number), this address is input to the address table 24, and correction data ΔX = −3H and ΔY = + 1H are obtained.
The value of this correction data is the current address X = 1FH, Y =
2H, respectively, and the correction address X = 1CH, Y
= 3H is generated and the correction address X in the image memory 22 is generated.
Image data whose current address is X = 1FH and Y = 2H is stored in the pixel corresponding to = 1CH and Y = 3H.

If this scanning is performed over the entire image and the data is read by normal raster scanning, the read image will have no distortion.

The above operation can be easily executed in real time by simply referring to the table constituted by the ROM, adding its output and the current address.

The data length of the correction data depends on the distance (distance between corresponding points) required for the correction, and since the correction is performed in the vicinity of the pixel of the distorted image, X, Y in the address table 24. The data length may be shorter than that of storing the address as it is.

For example, assuming that the image size is 512 × 512 pixels, if the X address and the Y address are to be stored as they are, 9 + 9 = 18 bits of data are required, but the correction range is +7 to each of the X address and the Y address.
If there are -8 pixels, 4 + 4 = 8 bits of data will do,
The table capacity is 8/18 compared to the former.

In this way, one screen of data is written to the image memory 22 while moving the pixel data to the corresponding points of the graphic distortion, and then read by normal raster scanning and D / A converted. By displaying it on the monitor, an image without graphic distortion can be seen.

FIG. 4 is a block diagram showing another embodiment of the present invention. In this embodiment, an X address latch 29 and a Y address latch 30 are added to the above embodiment.

The X address latch 29 and the Y address latch 30 hold the corrected address of the previous pixel, and the corrected address is used for the correction calculation of the next pixel.

That is, the X address generating means 25 and Y
When the corrected address is generated by the address generation means 26, the correction data is added to the address of the current pixel in the above-described embodiment. However, in the present embodiment, as shown in FIG. The correction data is added to the address.

The previous pixel address used for the address correction calculation of the top pixel of the screen is calculated in advance and set in the X address latch 29 and the Y address latch 30.

Therefore, according to the present embodiment, since the correction data is added to the corrected address of the previous pixel, the correction data length can be made shorter than that of the previous embodiment, and the data of the address table 24 is correspondingly reduced. The length can also be shortened.

In the above embodiment, the case where the number of the image memory 22 is one is explained, but the image memory 2
Since the frame input to 2 and the frame displaying its contents alternate, the screen may flicker slightly and the operation may be unnatural, but this does not cause any problem if it is used for a TV intercom.

If it is desired to eliminate this flicker, two image memories 22 are provided, these are alternately switched, and input and enlarged display are alternately repeated, so that a completely natural moving image can be displayed.

[0044]

As described above, in the television intercom of the present invention, when the image data obtained by A / D converting the video signal from the slave unit is written in the image memory,
The correction data for correcting the distortion due to the wide-angle lens,
Since it is set in advance in the address table and writing is performed according to the address after correction using this correction data, a wide-angle lens or the like is used as the image pickup means without using a large capacity address table. We were able to provide a TV intercom that does not cause distortion even when taking a wide-angle image.

Further, if the corrected address is held in the address latch and the corrected address is generated by adding the correction data to the corrected address of the previous pixel,
The capacity of the address table can be further reduced.

[Brief description of drawings]

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

FIG. 2 is a pattern diagram for explaining an operation of the above.

FIG. 3 is an operation explanatory diagram of the above.

FIG. 4 is a block diagram showing another embodiment of the present invention.

FIG. 5 is an operation explanatory diagram of the above.

[Explanation of symbols]

1 child device 2 parent device 3 transmission lines 11 Imaging means 12 Video output circuit 21 A / D conversion means 22 Image memory 23 Address generating means 24 address table 25 X address generation means 26 Y address generating means 27 D / A conversion means 28 monitors 29 X address latch 30 Y address latch

Claims (2)

[Claims] 1. A slave unit having an image pickup means for picking up an image of a visitor or the like, a video output circuit for outputting a video signal from the image pickup means to a transmission line, and a video signal transmitted through the transmission line is digitized. A / D converting means, an image memory for storing image data digitized by the A / D converting means, a D / A converting means for D / A converting image data read from the image memory, and a D / A In a television intercom comprising a master unit having a monitor for displaying an analog image signal output from the converting unit on a screen, an address generating unit for generating an address of the image memory from a video signal transmitted from a slave unit. And an address table that outputs correction data for address correction based on the generated address, and an address that generates a corrected address from the correction data A television intercom characterized in that a generating means is added and image data is written in the image memory by the corrected address. 2. An address latch for holding the corrected address is added, and the address generating means generates a corrected address from the address held in the address latch and the correction data. The TV intercom according to claim 1.