KR20040046319A - Image communication system - Google Patents

Abstract

PURPOSE: A video communication system is provided to display an image captured by a camera in various structures and colors. CONSTITUTION: A video decoder includes a buffer(101) for temporarily storing a bit stream, a variable length decoder(103) for decoding the bit stream stored in the buffer, an inverse quantizer(107) for inverse-quantizing the decoded data, and an inverse-discrete-cosine-transformer(109) for inverse-discrete-cosine-transforming the inverse-quantized data. The video decoder further includes a motion compensation unit(120) for compensating a motion vector in the image decoded by the inverse quantizer and the inverse-discrete-cosine-transformer, a display(140) for displaying a motion picture, a display selector(121) for varying the displayed motion picture in various manners, and a video frame memory(150) for storing the image displayed on the display.

Description

IMAGE COMMUNICATION SYSTEM}

The present invention relates to a video communication system, and more particularly, in the video communication field such as IMT-2000, when an image photographed by a camera is transmitted and displayed, it is possible to display a variety of colors and shapes by converting the display. The present invention relates to a video communication system capable of providing various video services to a user.

The current and future communication environment is rapidly changing beyond the distinction between wired and wireless areas and regional countries. In particular, future communication environments, such as IMT-2000, require users as well as video and audio. The trend is to build an environment that provides various information in real time or comprehensively.

In addition, the development of the personal mobile communication system is not only a voice communication in the cellular phone or PCS, but also to transmit text information as well as to access the Internet wirelessly using a personal mobile communication terminal, or to watch videos on TV It is being developed to transmit the data.

In particular, the digital television system that processes and transmits video data in real time, receives and displays it, and the video transmitted in real time is becoming an essential element in personal portable terminals using IMT-2000. .

In the related art, the portable terminal transmits and receives only human voice. However, due to the development of multimedia and the development of digital information processing technology, various information such as voice and video can be transmitted.

Above all, this technology has been commercialized. First of all, the analog video signal is subjected to special digital processing such as quantization and variable length encoding, and then included in the digital information and transmitted. It greatly contributed to the development of video compression technology that allows abundant information transmission and reception.

1 is a view schematically illustrating a process of transmitting and receiving an image in a communication system according to the prior art.

As shown in FIG. 1, when an image signal photographing a real object enters the input image unit 10 in an image communication system such as an IMT-2000 terminal, an analog signal is first converted into R, G, and B to encode the signal. After conversion into a digital signal, it is input to the video encoder 20 to encode it.

When the image signal photographed by the camera is input to the input image unit 10, the image signal is converted into R, G, and B digital signals, and then converted into a luminance signal and a color difference signal so as to be encoded.

That is, the object portion and the background portion of the captured image signal are subdivided into small pixel areas, and the pixels are separated into luminance signals and chrominance signals to perform encoding.

The captured image signal is digitized and subdivided into one image frame, and the video encoder 20 performs encoding so that the divided image frames can be displayed in a series form.

In this case, the video communication terminal is generally encoded with a video frame size such as CIF (352 * 288) or QCIF (176 * 144), and transmitted in the size thereof.

The video encoder 20 generally refers to an image encoder. However, since the audio encoding method performs encoding by a method different from the image encoding method, the video encoder 20 includes a video encoder.

That is, video and audio are separately encoded, mixed, and transmitted in the form of a bitstream.

Therefore, a DCT (Discrete Cosine Transform) for encoding a luminance signal and a chrominance signal for the pixels of the image frame transmitted to the video encoder 20, a quantizer for quantizing the image signal converted into a frequency form, and quantization VLC (Variable Length Coding) for entropy of the video signal, a motion predictor, an inverse quantizer, an inverse DCT, and an image memory to predict the video signal and reduce coding and coding.

In the DCT and the quantization unit, the luminance signal and the chrominance signal are encoded. The encoding is performed in a macroblock unit in which each 16 * 16 pixel is a unit in an image frame unit.

The motion predictor, the inverse quantization unit, the inverse DCT, and the image memory are used to reduce the bit rate of encoding by restoring and storing the encoded image again and using it as a reference image of the image to be encoded next. .

In addition, when the encoded video is the first video and is not stored in the video memory (I-frame), encoding for intra prediction is performed, and then motion estimation is performed for macro frames of video frames for P frames. To perform encoding.

That is, the encoder determines the first input image as an intra image frame, performs a prediction by encoding in the image frame itself, and then encodes the intra image frame, and then inputs an image frame that has been previously encoded. The motion is encoded by estimating the motion from.

In this way, the image captured by the camera is separated into a plurality of image frames, and the encoding is performed. The compressed image is compressed into one bitstream and transmitted.

When the bitstream encoded as described above is transmitted and received by the video decoder 30, the received image stream is temporarily stored in the reception buffer and temporarily received, and the video bitstream is stored in the same manner as in the video encoder 20. The video decoding process of separating the video signal and the audio signal is performed.

The video decoder 30 which reconstructs the image may perform variable length decoding on the VLC bitstream of the video encoder 20, and proceed in reverse of the compression scheme performed by the video encoder 20. It consists of Inverse Quantization, Inverse Discrete Cosine Transform (DCT), Motion Vector Compensation (MC) that performs inverse quantization and inverse discrete cosine transform. The display unit 40 restores and displays the image.

However, as described above, in a conventional communication terminal such as a video telephone, there is a limit in providing various display services to a user by collectively transmitting and displaying images captured by a camera in a size of QCIF or CIF.

The present invention provides a variety of services to users by converting and displaying images taken by a camera in a terminal used for video communication, such as IMT-2000, into a variety of structures and colors without displaying them in a standardized rectangular structure. The purpose is to provide a video communication system that can provide.

1 is a view schematically showing a process of transmitting and receiving an image in a video communication system according to the prior art.

2 is a block diagram showing the structure of a video decoder according to the present invention.

3 is a diagram illustrating a process of transmitting and receiving an image in a video communication system according to the present invention;

* Description of the symbols for the main parts of the drawings *

101: buffer section 103: VLD

107: inverse quantization unit 109: inverse DCT

120: MC121: display selector

140: display unit 150: image frame memory

In order to achieve the above object, the video communication system according to the present invention,

A buffer unit which receives the compressed image bitstream and temporarily stores the compressed image bitstream;

A VLD for variably decoding the bitstream subjected to VLC processing in the buffer unit;

An inverse quantizer for inversely quantizing a variable-length decoded signal in the VLD;

An inverse DCT for transforming an inverse quantized image signal by the inverse quantization unit to obtain a pixel coefficient value of a block;

A display unit configured to display according to the inverted pixel count value;

A display selector for selecting a shape change of a screen displayed on the display unit; And

An MC and an image frame memory for performing motion estimation using a variable length decoded signal in the VLD and an image displayed on the display unit; Characterized in that it comprises a.

Here, the display selector converts the decoded video signal into various shapes such as circles, triangles, rhombuses, stars, and the like, and displays the screen. In the screen shape conversion, an area other than the displayed image is a pixel value having a specific color. It is characterized by processing.

According to the present invention, by allowing the user to display the image taken by the camera in various shapes and various colors in the video telephone system, it is possible to provide differentiated video services to the user.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram showing the structure of a video decoder according to the present invention.

As shown in FIG. 3, when the encoded image data enters the video decoder in the form of a bit stream, decoding is performed as opposed to encoding performed by an encoder in order to reconstruct the original image.

Therefore, the decoder for decoding the compressed bitstream performs a decoding operation to reproduce the bitstream stored in the buffer unit 101 and the bitstream stored in the buffer unit 101 as an image temporarily. The variable length decoder (VLD 103) and the variable length decoded signal from the variable length decoder (103) are subjected to quantization and inverse discrete cosine transform processing as opposed to the compression scheme performed by the encoder for image reproduction. Motion Compensation (MC 120) for compensating a motion vector in an image decoded by an inverse quantization unit 107, an inverse discrete cosine transform 109, and an inverse quantization unit 107 and an inverse DCT ), A display unit 140 for displaying a video, and a display for selecting the display image by converting the displayed image in various ways. It is composed of image frame memory 150 for storing the previous image displayed in the selector 121, the display unit 140.

The process of reproducing the compressed video by the decoder having the above structure is as follows.

When an analog image signal is received by a decoder in a compressed bit stream state, the variable frame coded image frame signal is received through a discrete cosine transform and a quantization at an encoder. First, it is stored in the buffer unit 101 to temporarily store it.

The compressed video bitstream stored in the buffer unit 101 converts the value, length, etc. of the compressed bitstream by the variable length decoder 103 into two-dimensional encoding.

Then, the compressed image applied from the VLD 103 is reconstructed in the opposite direction as when the encoder is compressed by the encoder. The inverse quantization unit 107 performs inverse scanning and inverse quantization, and then performs inverse discrete cosine transformer (IDCT) 109 to perform IDCT conversion.

The inverse discrete cosine transform is input to the adder 110. In the adder 110, the reconstructed image frame is an intra mode image that is first started, or a previous image frame. After determining whether the INTER mode image exists, the display unit 140 directly reproduces the image because there is no motion vector in the case of the intra mode image.

The motion compensator (MC) 120 obtains and decodes a difference between a motion vector of an image frame currently decoded and a previous image frame from the image frame memory 150 in which previous image frames reproduced in the display unit 140 are stored. Compensate for the video being

In this case, the user selects various types of images from the display selector 121 connected to the display unit 140, and thus the quadrangular image is converted into a circle, an ellipse, a triangle, a rhombus, and a star shape.

In this case, the decoding process of the transformed image is performed by inverse quantization and inverse DCT, and the decoding process is performed in the same way as in the conventional method where the inside of the circle, ellipse, etc. exists, and the outer region where the image does not exist has a specific color. The decoding is performed by unifying the pixels.

Then, although various types of images can be displayed, the amount of decoding calculation is reduced in the pixel area unified with a specific color.

3 is a diagram illustrating a process of transmitting and receiving an image in a video communication system according to the present invention.

As shown in FIG. 3, when an image signal photographing a real object enters the input image unit 100 in an image communication system such as an IMT-2000 terminal, an analog signal is first converted into R, G, and B digital signals in order to encode the signal. After conversion to a signal, it is input to a video encoder to encode it.

When the image signal photographed by the camera is input to the input image unit 100, the image signal is converted into R, G, and B digital signals, and then converted into a luminance signal and a chrominance signal so as to be encoded.

That is, the object portion and the background portion of the captured image signal are subdivided into small pixel areas, and the pixels are separated into luminance signals and chrominance signals to perform encoding.

Accordingly, the image signal is transmitted to the video encoder 200 to perform a DCT (Discrete Cosine Transform) for encoding the luminance signal and the chrominance signals for the pixels of the image frame, and a quantizer for quantizing the image signal converted into a frequency form; VLC (Variable Length Coding) for entropy of quantized video signal, motion predictor, inverse quantizer, inverse DCT and video memory to predict video signal and reduce coding coding The signal is processed.

That is, the DCT and the quantization unit encode the luminance signal and the chrominance signal, and the encoding is performed in the macroblock unit in which each 16 * 16 pixel is one unit in the image frame unit.

In this way, the image captured by the camera is converted into a luminance signal and a color difference signal, and encoded, and transmitted in a bitstream form.

When the bitstream encoded as described above is transmitted and received by the video decoder 300, the received image stream is temporarily stored in the reception buffer and temporarily received. The video decoding process of separating the video signal and the audio signal is performed.

The video decoder 300 reconstructing the image may perform a variable length decoding of the VLC bitstream from the encoder and perform inverse quantization and inverse discrete in order to reverse the compression scheme performed by the video encoder 200. An inverse quantization unit for performing the cosine transform, an inverse discrete cosine transform (DCT), and a motion vector compensation (MC). The display unit 400 displays an image. Choose from different shapes and colors for your users to see.

When the video decoder decodes the image bitstream, if the shape and color of the user-selected image are selected, the RGB conversion routine decodes the selected circle, triangle, rhombus, star, and the like.

That is, when converting from a rectangular image frame to a circle, the video decoder fills an area other than the circle with a specific color and decodes only the image displayed inside the circle.

In this case, the computation of the video decoder can be reduced because the color of the region outside the circle is reconstructed in a batch without performing a decoding process.

In the same way, not only the circle shape but also images of other shapes are displayed in the same manner.

Accordingly, the display having the desired shape is performed by storing the modified structure image only in the display memory without changing the encoded image bitstream image.

As described in detail above, the present invention has an effect of providing a variety of services to the user by converting the shape of the displayed image into various structures when decoding the image photographed by the camera in the decoder.

In addition, there is an advantage that the amount of encoding calculation in the decoder can be reduced by converting the video into various types of images.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

Claims (3)

A buffer unit which receives the compressed image bitstream and temporarily stores the compressed image bitstream; A VLD for variable length decoding the VLC processed bit stream in the buffer unit; An inverse quantizer for inversely quantizing a variable-length decoded signal in the VLD; An inverse DCT for transforming an inverse quantized image signal by the inverse quantization unit to obtain a pixel coefficient value of a block; A display unit configured to display according to the inverted pixel count value; A display selector for selecting a shape change of a screen displayed on the display unit; And An MC and an image frame memory for performing motion estimation using a variable length decoded signal in the VLD and an image displayed on the display unit; Video communication system comprising a. The method of claim 1, And the display selector converts the decoded video signal into various shapes such as circles, triangles, rhombuses, and stars to display the converted video signals. The method of claim 1, And the screen type conversion is performed by processing an area other than the displayed image as pixel values having a specific color.