JPH03241993A - Picture transmitter - Google Patents

Abstract

PURPOSE:To improve the efficiency of information transmission by devising the picture transmitter such that a background picture with a low value or undesired of transmission as information is replaced into an optional background picture decided in advance by a sender as the preprocessing of input picture coding. CONSTITUTION:When a chromakie signal 25 is outputted, a control circuit 26 output a switching control signal 27 to a background synthesizer 24. Then a background changeover circuit 40 is activated and a background memory 41 is selected and in other case, a signal input terminal is selected. Thus, an optional picture for background synthesis is stored in the background memory 41 and when a switching control signal 27 representing the background part is inputted simultaneously to the background synthesizer 24, a preset background picture is used to replace the background of the input picture and the resulting signal is sent. Thus, the background is replaced into an optional background picture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image transmission device, and particularly to an image transmission device that transmits a background image by switching it to a predetermined arbitrary image.

[Prior Art] FIG. 5 is a block diagram of a conventional image transmission device disclosed in, for example, Japanese Patent Application Laid-Open No. 57-157696.

In the figure, the signal input terminal (1) is connected to differential circuits (3) and (5);
) are connected to frame memories (2) and (4), respectively.

Difference circuits (3) and (5) are both difference comparison circuits (6)
It is connected to the. The difference circuits (3) and (5) are further connected to a switching circuit (7), and the difference circuit (5) and the difference comparison circuit (6) are connected to a switching circuit (8).

The switching circuit (7) is sequentially connected to a quantization circuit (9), a variable length encoding circuit (11), a multiplexing circuit (13), a buffer memory (14), and a data output terminal (15). Also, a quantization circuit (9) and a switching circuit (8)
is connected to the adder circuit (10), and the adder circuit (10) is connected to the adder circuit (10).
0) is connected to frame memories (2) and (4).

The control signal generation circuit (12) also includes a multiplexing circuit (13).
)It is connected to the.

Furthermore, in this figure, a control circuit (19) is provided, which is connected to the multiplexing circuit (13) and the switching circuits (7), (8).

The control circuit (19) is connected to the frame memory (2).

Furthermore, the difference comparison circuit (6) is composed of absolute value circuits (16) and (17) and a comparison circuit (18). The above-mentioned difference circuits (3) and (5) are respectively absolute value circuits (
16) and (17), and the absolute value circuit (1
6) and (17) are both connected to a comparison circuit (18), and the comparison circuit (18) is connected to the switching circuit (7), (8
) and a multiplexing circuit (13).

Further, the frame memory (2) includes a memory section (20) connected to the differential circuit (3) and a switching circuit (21) provided at the input end of the memory section (20).

The control circuit (19) is connected to this switching circuit (21), and the switching circuit (21) is connected to the adding circuit (10).

In such conventional devices, the digitized image signal input manually from the signal input terminal (1) is sent to the differential circuit (3).
, (5). Double plug circuit (3), (
5) outputs the outputs of the frame memories (2) and (4) respectively connected from this input signal, and supplies the difference value to the switching circuit (7) and the difference comparison circuit (6).

In this difference comparison circuit (6), the difference circuit (3).

The absolute value for the signal supplied from (5) is created in absolute value circuits (16) and (17), and the comparison circuit (
In step 18), the magnitudes of both absolute values are compared. The output of the comparator circuit (18) becomes "1" when the output of the absolute value circuit (16) is smaller or equal, and becomes "O" in other cases. 8)
and is output to the multiplexing circuit (13). Switching circuit (
7) connects the difference circuit (3) to the quantization circuit (9) when the output of the comparison circuit (18) is "1", and connects the difference circuit (5) when the output is "O". The output of the control circuit (19) is “1”
'', both switching circuits (7) and (8) connect the difference circuit (3) and frame memory (2) to the quantization circuit (9) and addition circuit (10), respectively, with the highest priority.

The output of the switching circuit (7) is quantized in a quantization circuit (9) based on a predetermined quantization characteristic, and then sent to an addition circuit (
10) The signal is subjected to predetermined encoding in the variable length encoding circuit (11) and is supplied to the multiplexing circuit (13). The multiplexing circuit (13) includes a comparison circuit (18) and a control circuit (19).
Based on the outputs of the variable length encoding circuit (11) and the control signal generation circuit (12), the outputs of the variable length encoding circuit (11) and the control signal generation circuit (12) are multiplexed. Control circuit (1
When the output of 9) becomes "1", the multiplexing circuit (13) sends a signal representing rewriting of the frame memory (2) from among the outputs of the control signal generating circuit (12) at the rising edge of the multiplexing circuit (13). do.

Furthermore, when the output of the comparator circuit (18) changes, the multiplexing circuit (13) performs
Signals representing rising and falling states are selected from among the outputs of the control signal generating circuit (12) and sent out. At other times, the output of the variable length encoding circuit (11) is sent out. The buffer memory (14) is connected to the multiplexing circuit (1
3) is temporarily stored and output to the data output terminal (15).

The frame memory (2) consists of a memory section (20) and a switching circuit (21). The frame memory (2) is a memory for writing a background image, and when writing a background image in advance, the control circuit (1) or "1"
In response to this, the switching circuit (21) is switched and the adder circuit (10) is connected to the memory section (20). Therefore, the contents of the memory section (20) are rewritten by the output from the adder circuit (10).

After writing the background image into the memory section (20), the control circuit (9) emits "0", and the switching circuit (21) is switched accordingly, and the input and output terminals of the memory section (20) are closed. connected in a similar manner. With this, the memory section (20)
The contents of are retained.

That is, the control circuit (19) becomes "1" for a predetermined period when it is desired to write only the foreground image into the frame memory (2), and becomes "0" after the writing to the frame memory (2) is completed.
As a result, the background image is written into the frame memory (2), and thereafter, the background image is held during communication.

[Problems to be Solved by the Invention] Conventional image transmission devices have the above-mentioned configuration, so background information, which has relatively low value relative to personal information, must be transmitted as a real image. There were some issues that needed to be resolved, such as there being no way to change the background even if you didn't want the receiver or receiver to know what the background looked like.

The present invention was made in order to solve this problem, and an object of the present invention is to obtain an image transmission device that can replace a less necessary background portion with an arbitrary background image.

[Means for Solving the Problems] An image transmission device according to the second invention includes a subtraction circuit that subtracts color information of a background image, which is not stored in advance, from a pixel value of a color difference signal of an input signal. a background detector that detects only the background area; a control circuit that emits a control signal indicating the background area detected by the 17-view detector; and a control circuit that emits a control signal indicating the background area detected by the background detector; and a background synthesizer that replaces a background area with a predetermined arbitrary image.

[Function] According to the image transmission device of this invention, an arbitrary image is inserted into the background area detected from the manually generated image and transmitted, so background information that the transmitter does not want to be known can be removed. Alternatively, it is possible to transmit a background image of the child that is predetermined by the sender, such as a background that gives a good impression to the recipient.

[Example] Next, the present invention will be explained in more detail with reference to an example according to the invention shown in FIGS. 1 to 4.

FIG. 1 shows the configuration of an image transmission station according to an embodiment of the present invention.

In this figure, the signal input terminal (1) is connected to the background detector (
23), background synthesizer (24), difference circuit (3), encoder (29), switching circuit (31), variable length encoder (32), buffer (14) and data output terminal (1
5) are sequentially connected.

The background detector (23) is also connected to a control circuit (26), which controls the background synthesizer (24).
) and the control signal generation circuit (12). The control signal generation circuit (12) is connected to the switching circuit (31). Further, the difference circuit (3) is connected to the frame memory (2) and the addition circuit (10), and the addition circuit (10) is connected to the frame memory (2).

On the other hand, the encoder (29) is connected to the adder circuit (10) via the decoder (30). Addition circuit (10
) is connected to the frame memory (2).

Next, the operation of the device shown in this figure will be explained.

In FIG. 1, a human input image signal (22) from a signal input terminal (1) is applied to a background synthesizer (24) via a background detector (23). This background synthesizer (24) uses a switching control signal (27) generated by a control circuit (26) based on a chromakey signal (25) from a background detector (23).
) can be switched. As a result of this switching, the background synthesizer (24) outputs a composite image signal (28) in which the background is replaced with a different one from the human-generated image signal (22).

Here, the configuration and operation of the background detector (23) and background synthesizer (24) will be explained in detail.

FIG. 2 shows the configuration of the background detector (23),
The background detector (23) shown in this figure is connected to an A/D converter (33) that takes in the input image signal (22) from the signal input terminal (1) and this A/D converter (33). Y
/C isolation circuit (34) is shown. The output terminal of this Y/C separation circuit (34) is connected to a difference circuit (36), and this difference circuit (36) has a threshold setting circuit (
35) is connected. The output of the differential circuit (36) is
It is sequentially connected to an absolute value circuit (37), a comparator (38), and a chromakey signal generator (39).

On the other hand, FIG. 3 shows the configuration of the background synthesizer (24), and the background synthesizer (24) shown in this figure is switched by the switching control signal (27) from the control circuit (26). It consists of a background switching circuit (40) and a background memory (41) connected to this background switching circuit (40).

Next, the operation will be explained. In FIG. 1, a background detector (23) detects a background portion of a human image signal (22) whose background is unified to the same color. Background detector (23
) scans in the scanning line direction and determines the background portion based on the near-zero level of the color difference signal, and outputs a chromakey signal (25) to the control circuit (26) for the background portion. The control circuit (26) receiving the chromakey signal (25) outputs a switching control signal (27) for identifying the background to the background synthesizer (23). The background synthesizer (24) inserts a pre-stored image into the background portion of the human image in response to a switching control signal (27) to create a composite image signal (28). The difference between the composite image signal (28) and the pre-encoded data (42) stored in the frame memory (2) is determined by a difference circuit (3). The difference signal (43) is encoded by an encoder (29), and this encoded data (44)
is output to the decoder (30) and variable length encoder (32). In the decoder (30), encoded data (4
4) is decoded and the decoded data (45
) is added to the pre-encoded data (42) in an adder (10). The locally decoded data (46) thus added by the adder (10) is stored in the frame memory (2) for use in encoding the next frame.

Further, the encoded data (44) is transferred to the switching circuit (31).
The signal is supplied to the variable length encoding circuit (32) via. The variable length encoding circuit performs encoding in the same manner as in the conventional example, and outputs a variable length encoded signal (48) to the buffer (14). The buffer (14) stores the variable length encoded signal (48), matches the transmission bit rate, and outputs the signal to the outside from the data output terminal (15).

Next, referring to FIG. 2, the operation of the background detector (23) will be explained. The analog input image signal (22) is converted into a digital signal (49) by an A/D converter (33). The digital signal (49) is separated into a luminance signal (50) and a color difference signal (5) by a Y/C separation circuit (34).

Furthermore, a color difference signal (51), a fixed value signal (52),
The difference is determined by a subtractor (36). Fixed value signal (
52) is a threshold setting device (52) having a threshold of the same level as the preset background color difference signal (51).
35). This difference signal (53
), the absolute value is determined by the absolute value circuit (37), and the absolute value signal (54) is output to the comparator (38).

When the absolute value signal (54) is close to zero, the comparator (38) considers that the absolute value signal (54) indicates a background part and sends a control signal +3 ( 55) is output. The chromakey signal generator rf39) that receives control number 15 (55) outputs a chromakey signal (25) for the volume portion.

In this way, when the number (25) is output to the chroma key, the control circuit (26) outputs the switching control signal (27) to the background synthesizer (24). Then, the background switching circuit (40) shown in FIG. 3 is activated, and the background memory (41) is activated.
) side, otherwise the signal input terminal (
1) Connected to the side.

Therefore, if the background memory (41) is prestored with any image used for background composition, such as a landscape painting, an image with a company name blanked out for advertising purposes, or an image of a product with a trademark for advertising purposes,
When a switching control signal (27) indicating a background portion is simultaneously input to the background synthesizer (24), it becomes possible to replace a preset background image as the background of the input image and transmit it as a signal.

The background image composition of this scene is shown in FIG.

Here, when the chroma key signal is "0", the scan position indicates a part other than the T"f view part, and the number (22) is output as is in the human image. However, when the chroma key signal is "1", the scan position The position indicates the background part, in this case,
Since the image is output by switching to the output signal of the background memory (41), the background at the top of the input image is removed, and the preset background is replaced and transmitted.

[Effects of the Invention] As explained above, the present invention uses an arbitrary background predetermined by the sender as a pre-processing for manual image encoding to extract an image that has low value as information or that the sender does not want to know. By replacing the image with a structure, it is possible to use a simple background, which has the effect of providing a device that is efficient in transmitting information.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an image transmission device according to an embodiment of the present invention, FIG. 2 is a block diagram of a background detector according to an embodiment of the present invention, and FIG. 3 is a background composition diagram according to an embodiment of the present invention. FIG. 4 is an explanatory diagram of background composition according to the present invention, and FIG. 5 is a block diagram of a conventional image transmission device. In the figure, (1) is a signal input terminal, and (2) is a signal input terminal. (4) is a frame memory, (3) and (5) are differential circuits, (9) are quantization circuits, (10) are addition circuits, (11)
) is a variable length encoding circuit, (12) is a control signal generation circuit,
(13) is a multiplexing circuit, (14) is a buffer memory, (
15) is a data output terminal, (16) and (17) are absolute value circuits, (18) are comparison circuits, (19) are control circuits, (20) are memory, (21) are switching circuits, (22) are
) is a human image signal, (23) is a background detector, (24) is a background synthesizer, (25) is a chromagey signal, (26) is a control circuit, (27) is a switching control signal, (28) is a composite image signal, (29) is an encoder, (30) is a decoder,
(31) is a switching circuit, (32) is a variable length encoder,
(33) is an A/D converter, (34) is a Y/C separation circuit,
(35) is a threshold setter, (36) is a differential circuit, (3
7) is an absolute value circuit, (38) is a comparator, (39) is a chromakey signal generator, (40) is a background switching circuit, (4)
1) is background memory, (42) pre-encoded data, (43)
difference signal, (44) encoded data, (45) composite data, (46) locally decoded data, (47) identification signal, (48) variable length encoded signal, (49) digital signal, (50) is a luminance signal, (51) is a color difference signal,
(52) is a fixed value signal, (53) is a difference signal, (54)
is an absolute value signal, and (55) is a control signal. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] It has a subtraction circuit that subtracts pre-stored background color difference information from the pixel value of the color difference signal of the input signal, and detects the background area of the input signal by comparing the output of this subtraction circuit with a predetermined threshold. a background detector; a control circuit that issues a control signal indicating a background area detected by the background detector; and a background area outputted by the background detector is stored in advance in response to the control signal issued by the control circuit. A background synthesizer that switches to a background image, a variable length encoder that variable length encodes the output of this background synthesizer, and a variable length encoder that temporarily stores the output of this variable length encoder to match the transmission bit rate. An image transmission device comprising a buffer for transmission.