KR100824264B1 - Apparatus and method for measuring image received via network - Google Patents

Abstract

An apparatus and a method for measuring quality of an image received via a communication network are provided to synchronize the receiving image received via the communication network with a reference image and evaluate image quality of the receiving image compared with the reference image in the synchronized state, thereby checking an image data transmitting/receiving state of the communication network. An interface unit(120) receives a receiving image, comprising a start sync image for informing start of a quality test and a test image for an actual quality test, through a communication network. A codec unit(130) decodes the receiving image, inputted through the interface, into a color signal. A test image detector(140) calculates a mean per each frame by confirming one value of contrast, chroma and color information of the color signal inputted from the codec, and detects a test image among the receiving images based on the calculated mean. An MOS(Mean Opinion Score) measuring unit synchronizing the test image, detected by the test image detector, with a reference image and compares image quality between the test image and the reference image in the synchronized state. After that, the MOS measuring unit calculates an MOS value according to the comparison result, and outputs the calculated MOS value.

Description

Apparatus and method for measuring image received via network}

1 is a network diagram of an image quality measurement system according to an embodiment of the present invention;

2 is a diagram illustrating a frame structure of an image for quality measurement according to an embodiment of the present invention;

3 is a functional module configuration diagram of an image quality measuring apparatus according to an embodiment of the present invention;

4 is a flowchart illustrating a method for measuring image quality according to an embodiment of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

100: image quality measuring device 110: terminal

120: interface unit 130: codec unit

140: test image detector 150: MOS measuring unit

160: display unit

200: VoIP Phone 300: Computer

400, 500: Mobile communication terminal 600: LCD monitor

700: mobile network 800: internet

The present invention relates to a quality measuring apparatus and method for an image passed through a communication network, and in particular, to compare the image quality between a received image input through a communication network and a reference image as a reference, and receiving a contrast to the reference image based on the comparison result The present invention relates to a quality measuring apparatus and method for an image passed through a communication network to check a state of transmission / reception of image data of a communication network by outputting a calculated value indicating an image quality.

In recent years, thanks to the rapid development of information / communication, mobile communication terminals are now common enough to be portable. Furthermore, voice calls and text message transmission / reception were the main functions. New models with various functions are being introduced one after another, quickly replacing the old ones. In particular, as the new concept of Digital Multimedia Broadcasting (DMB), which combines broadcasting and communication, is actively progressing in the industry, handset makers are also actively launching new models with DMB reception as their main function. The trend is.

In addition, until recently, access to the Internet has been common through wires, but recently, based on a platform such as WAP (Wireless Application Protocol) or WIPI, an access method through a mobile communication network or a public wireless LAN and an access point is used. (Access Point) allows access to the Internet. Furthermore, the mobile Internet (WiBro or WiMax) method, which enables high-speed Internet access even during stop or slow travel, is commercially available with ADSL quality and cost. Active development is underway.

Therefore, in the case of a terminal manufacturer, it is necessary to check the quality of the actual image received by the terminal manufactured by the terminal in order to provide a higher quality image quality to the customer. Although it is necessary to check the quality of the actual image passing through the network for the purpose of checking and optimizing the performance or state of the communication network, there has been a problem that development has not been made so far.

The present invention has been made to solve the above-described problem, and the received image received through the communication network is synchronized with the reference image as its reference, and the image quality of the received image compared to the reference image in this synchronized state to evaluate It is an object of the present invention to provide a quality measuring apparatus and method for an image passed through a communication network.

In order to achieve the above object, a quality measuring apparatus for an image which has passed through a communication network of the present invention is an interface for receiving a received image including a start synchronous image indicating the start of a quality test and a test image for an actual quality test through a communication network. part; A codec unit for decoding the received image input through the interface unit into a color signal; A test image for checking a value of any one of brightness, saturation, and color information of the color signal input from the codec unit, calculating an average value for each frame, and detecting a test image from the received image based on the calculated average value Detection unit; And synchronizing the test image detected by the test image detector to a reference image as a reference, comparing the image quality between the test image and the reference image in the synchronized state, and calculating a MOS value according to the comparison result. Provided is a quality measuring apparatus for an image that has passed through a communication network including an output MOS measuring unit.

In the above-described configuration, the interface unit preferably includes a function for generating a call for connection with a communication terminal or a function for controlling a video protocol for receiving an image, wherein the color signal is an RGB or YUV signal. It would be desirable.

According to another exemplary embodiment of the present invention, a quality measurement method for an image passed through a communication network includes a start synchronous image indicating a start of a quality test received through a communication network and a received image including a test image for an actual quality test. A quality measuring method for an image passed through a communication network for comparing with a reference image and calculating a MOS value according to the comparison result, the method comprising: decoding the received image into a color signal; (B) checking a value of any one of brightness, saturation and color information of the color signal decoded in the step (a) and calculating an average value for each frame; (C) detecting a test image from the received image based on the average value calculated in step (b); (D) synchronizing the test image detected in step (c) with a reference image as a reference; (E) calculating an MOS value of the test image by comparing the image quality between the test image and the reference image in the synchronized state; And (f) outputting the MOS value calculated in step (e). Here, the color signal is preferably an RGB or YUV signal.

Before describing the present invention, a method of measuring image quality is proposed as a MOS algorithm. That is, in the present invention, the image received through the communication network is compared with the reference image, which is the reference image, using the Mean Opinion Score (MOS) algorithm, and the image quality grade of the received image compared to the reference image is calculated. Will be done. For example, the image quality rating of the received image may be evaluated in five steps as shown in Table 1 below. Such a MOS algorithm is specifically defined in J.144 (rev. 1) recommended by ITU-T. It would be desirable to be a MOS algorithm.

Meanwhile, as the received image is received through a communication network, it is important to synchronize the received image with the reference image for accurate image quality test, which will be described below. A detailed description will be given of a quality measuring apparatus and method for an image passed through a communication network of the present invention.

MOS value Quality grade 5 Excel 4 Good 3 Fair 2 Poor One Bad

1 is a diagram illustrating a network configuration of an image quality measuring system according to an exemplary embodiment of the present invention.

As shown in FIG. 1, according to the image quality measuring system of the present invention, a MOS measurement and a computer 300 for an image transmitted / received between the mobile communication terminals 400 and 500 through the mobile communication network 700. And MOS measurement for the image received by the mobile communication terminal 500 via the Internet 800 and the mobile communication network 700 from the VoIP phone 200 capable of video calling, and from the mobile communication terminal 400. MOS measurement for the image received via the mobile communication network 700 and the Internet 800 will be possible. In addition, at least one of the mobile communication network 700 and the Internet 800 from a server for providing an image constructed by a content provider (CP), etc., rather than the terminals 200, 300, and 400 shown in FIG. It is also possible to measure the MOS of the image received via. Accordingly, the image quality measuring apparatus 100 according to the present invention measures the quality of the image received through the Internet 800 or is connected to the mobile communication terminal 500 and the quality of the image received through the mobile communication network 700. The quality test image and the resultant MOS measurement value may be output through the LCD monitor 600. Here, it is preferable that the image quality measuring apparatus 100 is equipped with a wireless frequency transmission / reception module which enables wireless connection directly to the Internet 800 or the mobile communication network 700. Accordingly, the image quality measuring apparatus 100 is provided. The mobility can be further ensured so that the vehicle can compare and measure the actual image quality in each region, for example, each base station.

On the other hand, Figure 2 is a diagram illustrating a frame structure of the image for quality measurement according to an embodiment of the present invention, as shown in Figure 2 the structure of the received image input to the image quality measuring apparatus 100 is a quality test It may be made to include the 'starter video' for the start of the synchronization, the actual 'test video', and the 'end notification video' to inform the end of the test. Here, the start sync image and the test image should be clearly different in contrast, hue, or saturation. For example, the white sync information may be recorded in every pixel of the start sync frame to be clearly contrasted with the test video. .

3 is a configuration diagram of a functional module of an image quality measuring apparatus according to an embodiment of the present invention.

As shown in FIG. 3, the configuration of the image quality measuring apparatus 100 according to the present invention includes a terminal 110 for inputting / outputting various data including an image; A module having a complex function of receiving an image passing through a mobile communication network 700 or the Internet 800, and is configured to generate a call for connection with another mobile communication terminal 400 or a VoIP phone 200. It performs a function of controlling the terminal 500 or directly generating a call, connecting to the computer 300 via the Internet 800, and controlling various video protocols to receive an image. An interface unit 120; A codec 130 for decoding (extending) the image received through the interface unit 120 into a 'color signal' such as a YUV signal or an RGB signal; The test image detector 140 checks the brightness (other than saturation or hue) value of the color signal decoded by the codec unit 130, calculates an average value per frame, and detects and stores a test image from the received image based on the calculated average value. ); A MOS measuring unit 150 for comparing the quality of the test image detected by the test image detecting unit 140 to a reference image as a reference to calculate a MOS value of the test image; And a display unit 160 displaying the test image input from the test image detector 140 and the MOS value input from the MOS measuring unit 150. In this case, when the image received through the interface unit 120 is already decoded as a color signal, the image may be directly input to the test image detector 140 without passing through the codec unit 130.

On the other hand, there are typically RGB and YUV schemes for color representation. In the RGB scheme, up to 8 bits are allocated to R, G, and B, respectively, and 16,777,216 (24 powers of 2) colors can be represented. In general, the brighter the color, the larger the number allocated to RGB. Therefore, what can be used as the start synchronous frame will usually be a white screen, and the reference value for determining whether or not the test image detection unit 140 is a white screen, that is, the reference value for the detection of the test image in advance It will be set. Accordingly, when the calculated average value is greater than or equal to the reference value, the test image detector 140 determines that the corresponding frame is a start synchronous frame (or an end notification frame), that is, a white screen. The frame is determined to be detected as a test frame.

Next, the MOS measuring unit 150 specifically synchronizes the test image input from the test image detecting unit 140 with the pre-stored reference image, and compares the image quality of each frame in sequence in order to obtain the MOS value. The calculated MOS value is output to the display unit 160. Here, the MOS measuring unit 150 may calculate the MOS value for each frame, or may calculate the MOS value by averaging. For example, if any one frame of the test image is not transmitted because the communication network is extremely unstable, the MOS values output to the display unit 160 are not synchronized between the test image and the reference image. It could be '1' as one did.

4 is a flowchart illustrating a method for measuring image quality according to an embodiment of the present invention. The subject of the flowchart is an image quality measuring apparatus 100, and a receiving side mobile communication terminal (hereinafter, referred to as a receiving terminal) 500 Note that the description will be made by receiving the image from the transmitting mobile communication terminal (hereinafter referred to as the transmitting terminal) 400 in the state connected to the).

First, step S11 is a step of requesting the mobile communication terminal 500 an image for the image quality test, specifically controlling the receiving terminal 500 to generate a call to the transmitting terminal 400. Accordingly, both terminals 400 and 500 are connected to each other, and the transmitting terminal 400 transmits the received image to the receiving terminal 500 as shown in FIG. 2. At this time, the reception image is prepared in advance on the transmitting terminal 400 side, may be stored in the memory of the transmitting terminal 400, or that is located in any notebook computer via the transmitting terminal 400 via the receiving terminal 500 ) May be transmitted.

Next, in step S13, the image protocol is controlled to receive an image from the transmitting terminal 400, and in step S15, the received image is decoded into an RGB signal, and the brightness value of the decoded RGB signal is checked (step S17). The average brightness value is calculated per frame (step S19).

Subsequently, the process proceeds to step S21 to determine whether the average brightness value thus calculated is equal to or less than a predefined reference value. In other words, step S21 is a process of determining whether the corresponding frame is a start sync frame (or end notification frame) or a test frame.

As a result of the determination in step S21, if it is not equal to or less than the reference value, the process proceeds to step S23 to determine again whether or not the RGB signal to be decoded continues. That is, the progress from step S21 to step S23 is due to the determination result in step S21 that the corresponding frame is a start sync frame or an end notification frame. Therefore, as a result of the determination in step S23, when the RGB signal is still present, the process returns to step S17 and steps S17 to 21 are repeated.

On the other hand, if it is determined in step S21 that the average brightness value calculated in step S19 is greater than or equal to a predetermined reference value, the process proceeds to step S25 to detect the corresponding frame, and returns to step S17 to repeat steps S17 to 21. . Here, step S25 will be repeated until the end notification frame is input.

In addition, as a result of the determination in step S23, when the RGB signal is not input, that is, when all the received images are received, the test frame detection process is completed.

Next, the step S27 is performed to compare the image quality between the detected test image and the reference image as a reference, calculate the MOS value which is the comparison result (step S29), and display the detected test image (step S31). The MOS value of the displayed test image is output (step S33).

The apparatus and method for measuring a quality of an image passing through a communication network of the present invention is not limited to the above-described embodiments and can be modified in various ways within the scope of the technical idea of the present invention.

According to the apparatus and method for measuring a quality of an image passed through a communication network of the present invention as described above, the received image received through the communication network is synchronized with a reference image as a reference, and compared with the reference image in this synchronized state. By evaluating the image quality of the received image, it is possible to check the state of transmitting / receiving image data of the communication network.

Claims (6)

An interface unit for receiving a received image including a start synchronous image indicating the start of a quality test and a test image for a real quality test through a communication network; A codec unit for decoding the received image input through the interface unit into a color signal; A test image which checks a value of any one of brightness, saturation and color information of the color signal input from the codec unit, calculates an average value for each frame, and detects a test image from the received image based on the calculated average value Detection unit; And The test image detected by the test image detector is synchronized with a reference image as a reference, and the image quality is compared between the test image and the reference image in the synchronized state, and the MOS value is calculated and output according to the comparison result. Including the MOS measurement unit, The color signal quality measuring apparatus for an image passed through a communication network, characterized in that the RGB or YUV signal. The method of claim 1, And the interface unit includes a function for generating a call for connection with a communication terminal. The method of claim 1, And the interface unit includes a function of controlling an image protocol for receiving an image. delete Comparing the received image including the start synchronous image indicating the start of the quality test received through the communication network and the test image for the actual quality test with the reference image as a reference, and calculates the MOS value according to the comparison result In the quality measurement method for the image passed through the communication network, (A) decoding the received image into a color signal; (B) checking a value of any one of brightness, saturation and color information of the color signal decoded in the step (a) and calculating an average value for each frame; (C) detecting a test image from the received image based on the average value calculated in step (b); (D) synchronizing the test image detected in step (c) with a reference image as a reference; (E) calculating a MOS value of the test image by comparing the image quality between the test image and the reference image in the synchronized state; And And (f) outputting the MOS value calculated in step (e). The color signal is a quality measurement method for an image passed through a communication network, characterized in that the RGB or YUV signal. delete

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