JPH033586A - Picture transmitter - Google Patents

Abstract

PURPOSE:To attain display of superimposition even when a picture is sent by a different data compression system by converting the data form and the dynamic range of a picture data subjected to superimposition display. CONSTITUTION:A 1st picture data such as a moving picture data is converted into a 2nd picture data such as the same data form as a still picture data by a data form conversion circuit 13 and a 1st picture data outputted from the data form conversion circuit 13 is matched with the dynamic range of the 2nd picture data at a dynamic range conversion circuit 14. Even when the data form and the dynamic range of the 1st and 2nd picture data are different from each other, the both are displayed superimposingly.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an image transmission device for incorporating and displaying a moving image in a still image, particularly an image transmission device that combines still images and moving images having different data formats and dynamic ranges. Regarding.

[Prior art] In recent years, the operation of advanced information communication networks mainly based on digital communication has begun, and the 15DN switching network has begun to be put into practical use in some areas, so the transmission of videos, still images, etc. using these communication lines has become increasingly difficult. Videophone and videoconferencing systems that are capable of this have been developed. With the development of semiconductor technology such as LSI, the cost and size of systems have been reduced, and image transmission devices such as video telephones and video conference systems are being commercialized.

Here, a conventional image transmission device will be explained based on FIG. 3. In the figure, (1) is a still image frame memory that temporarily stores still images captured from the own station's TV camera, scanner, etc., or still images sent from the ground (communication partner), and (2) is a frame memory for still images. A video frame memory that stores video images, (3) a reduction circuit that reduces the data in the video frame memory (2) by filtering, subsampling, etc., and (4) a video display system that displays video images and a still image. a synchronization absorption buffer for absorbing the synchronization difference with the still image display system that displays the image and reading the video data in accordance with the still image display system; (5) a switch for selectively switching between video data and still image data; (6) is a switch (
5) a video display position detection circuit that generates a switching timing signal; (7) a still image D/A converter that converts digital data output from the switch (5) into an analog signal;
(8) converts the analog signal output from the still image D/A converter (7) into a so-called NTS C (National
lTelevision System Comm1t
NTSC encoder for still images that converts to tee) signals,
(9) is a still image display that displays still images, (1
o) is a video D that converts the digital video data read out by the video frame memory (2) into an analog signal.
/A converter, (11) is a video NTSC encoder that converts the analog image signal output from the video D/A converter (10) into an NTSC signal, and (12) is a video display that displays video images. be.

Next, the operation of this conventional example will be explained. When transmitting an image, first, an image signal inputted by an image signal input means (not shown) such as a video camera is converted into a digital signal for each predetermined pixel and stored in a video frame memory for transmission (not shown). One screen worth of data is stored in (Z). Since the amount of data stored in this video frame memory is enormous, it is impractical to transmit it as is. That is, the input image data is a normal CRT.
Because it is synchronized with the scanning in etc., about 30 screens are input per second. Then, let the number of pixel data in the video frame memory be, for example, 160×100,
Even when the brightness is set to 8 gradations, there are 3 bits per pixel, 48 Kbits per screen, and 1 bit per second.
．． It requires 44 Mbit of information. Since two color signals are required for each pixel, three times the amount of information is normally required.

Therefore, data compression processing is generally performed on video data. That is, the image data stored in the video frame memory is divided into predetermined blocks, and this is compared with pre-stored brightness patterns etc. and encoded, or compared with the data of the previous frame and encoded. Perform data compression processing such as The thus encoded data is then transmitted to the other party via the communication line.

On the other hand, when receiving an image signal, the received image signal is decoded and restored into digital image data, which is written into the moving image frame memory (2). The video frame memory (2) is constantly read out for video display, and the read image data is stored in the D
/A converter (10) converts the signal into an analog component signal, and then the NTSC encoder (11) converts it into the so-called N signal, which is the standard for TV color broadcasting.
It is converted into a TSC signal and displayed on the display (12).

On the other hand, the transmission of still images is exactly the same as the above-described case of moving images, except that the concept of time is not required in the transmission and the data compression method is different. That is, the still image data is read out from the still image memory, encoded, and then transmitted. Furthermore, image data received from the ground is decoded and then stored in the still image frame memory (1). This still image frame memory (1) is always read out for display as in the case of moving images, and the read still image data is transferred to the still image D/A converter ( 7
) is converted into an analog component signal, and then converted into an NTSC signal by an NTSC encoder and displayed on a still image display (9).

Furthermore, in the conventional example shown in FIG.
By this operation, a moving image (child screen) can be reduced to a small size and displayed superimposed on a still image (main screen) as shown in FIG. That is, the data read from the moving image frame memory (2) in FIG. 2 is filtered and subsampled and reduced by the reduction circuit (3). The image data thus reduced is supplied to the switch (5) via the synchronization absorption buffer (4).

The synchronization absorption buffer is for absorbing the synchronization difference between the moving image display system and the still image display system, which are operating independently.The image data that has passed through the synchronization absorption buffer (4) is the image data in the still image system. It is synchronized with.

The switch (5) is connected to the video display position detection circuit (6).
controlled by signals supplied from the That is,
For the data of the desired display position of the image data read out from the still image frame memory (1), select the switch (5).
) switches this to video data from the synchronization absorption buffer (4) and supplies it to the still image D/A converter (7).
On the still image display (9), an image as shown in FIG. 3 is obtained in which a reduced moving image is written at a desired position.

Note that the video display position detection circuit (6) detects the display position of the video from the synchronization signal of the still image display system and supplies this to the switch (5), so the switch (5) You can insert the video in the desired position. In this way, a moving image can be reduced to a small size and displayed superimposed on a still image.

[Problem to be solved by the invention] However, in order to perform the above-mentioned superimposed display,
The still image D/A converter (7) and the still image NTSC encoder (8) must also process moving images. For this reason, the data formats of video data and still image data (so-called two types of luminance and color difference data, for example Y
There is a data format such as UVSYIQ. ) and the dynamic range of the data itself must be the same.

Generally, the data format and dynamic range often depend on the data compression (encoding) method, and in order to perform the above-mentioned superimposed display, it was necessary to use the same data compression method for video and still images. . Therefore, when data compression methods with different data formats and dynamic ranges are employed, there is a problem that the two cannot be displayed in a superimposed manner.

This invention was made with the aim of solving the above-mentioned problems, and it is necessary to completely separate the moving image and still image systems and use data compression methods with different data formats and dynamic ranges. An object of the present invention is to obtain an image transmission device capable of superimposed display.

[Means for Solving the Problems] An image transmission device according to the present invention converts first image data (for example, video data) into the same data format as second image data (for example, still image data) in a data format conversion circuit. and the first output from this data format conversion circuit.
The second image data is matched with the dynamic range of the second image data in a dynamic range conversion circuit.

[Operation] The image transmission device according to the present invention transmits first image data (
For example, video data) is converted into the data format and dynamic range of second image data (still image data, for example), so if the data format and dynamic range of the first image data and second image data are different, Even though
Both can be displayed in a superimposed manner.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. Note that the same or corresponding parts as in the conventional example shown in FIG. 2 are given the same reference numerals, and the explanation thereof will be omitted.

The characteristic feature of this invention is that the synchronous absorption buffer (
A data format conversion circuit (13) for converting the data format and a dynamic range conversion circuit (14) for converting the dynamic range are provided between the switch 4) and the switch (5). Therefore, the video data read from the video frame memory (2) is filtered and subsampled and reduced by the reduction circuit (3) in the same way as in the conventional example, and then sent to the synchronization absorption buffer (4) for the still image display system. It is assumed that the signal is synchronized with the signal of

The video data output from the synchronization absorption buffer (4) in synchronization with the still image display system is transferred to the data format conversion circuit (
13). Here, consider a case where, for example, the compression methods are different for moving images and still images, and the data formats depending on the data compression methods are different. That is, for example, moving images are in the so-called YUV (Y, luminance data, U, V, two types of color difference data) format, and still image systems are in the so-called YIQ (Y: brightness data, I, Q: two types of color difference data). In this case, the data and format conversion circuit (13) converts YUV data to YIQ data. In addition, YUV format, YIQ format, RGB
The formats and the like are all for specifying colors, and there are predetermined relationships among them. Therefore, desired conversion can be performed using these relationships.

The moving image data whose data format has been converted into a still image data format in the data format conversion circuit (13) is subjected to dynamic range conversion by the dynamic range conversion circuit (14).

That is, the data whose values have been converted by the data format conversion circuit (13) through transformation between data formats have different dynamic ranges. This is because the dynamic range of the data itself is originally different depending on each format, and each data format has a different dynamic range.
This is because if what is displayed as a digital signal of a predetermined gradation is simply converted using a mathematical formula, the respective fluctuation widths will be different and the dynamic range will be different.

In this way, according to this embodiment, the data format and dynamic range of a moving image can be made to match that of a still image. Therefore, this is used as a still image D/A converter (7
), processed by the still image NTSC encoder (8) and displayed on the still image display (9), with the same brightness and color tone as the still image data read from the still image frame memory (1). Can be displayed in a superimposed manner.

Note that although the above embodiment has been described by taking as an example the superimposed display of a still image and a moving image, the same effect can be achieved in a superimposed display of still images or moving images. In addition, the display output for both videos and still images was an NTSC signal, but the RG
[Effect of the Invention] As explained above, according to the image transmission device according to the present invention, in order to convert the data format and dynamic range of image data to be displayed in a superimposed manner, mutually different data Even when images are transmitted using a compression method, they can be displayed in a superimposed manner.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of an image transmission device according to an embodiment of the present invention, FIG. 2 is a block diagram of the main parts of a conventional image transmission device, and FIG. 3 is an explanatory diagram showing a superimposed display screen. be. In the figure, (1) is frame memory for still images, (2)
is a video frame memory, (3) is a reduction circuit, (4) is a synchronization absorption buffer, (5) is a switch (combining means), (6
) is a video display position detection circuit, (7) is a still image D/A converter, (8) is a still image NTSC encoder, (9) is a still image display, and (10) is a video D/A converter. (11) is a video NTSC encoder, (12) is a video display, (13) is a data format conversion circuit, (
14) is a dynamic range conversion circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In an image transmission device that transmits and receives image data via a transmission path, a first device that stores image data expressed in a first data format;
a second image memory for storing image data represented in a second data format;
an image memory, a reduction circuit for reducing the image data read from the first image memory, and converting the reduced image data read from the reduction circuit into the data format of the second image data. a dynamic range conversion circuit that converts the dynamic range of the reduced image data output from the data format conversion circuit to match the dynamic range of the second image data; and this dynamic range conversion circuit. combining means for inserting the reduced image data outputted from the image data into a part of the image data read from the second image memory and incorporating the reduced first image data into the second image data; An image transmission device comprising: