KR20070060998A - Display method in small terminal - Google Patents

Abstract

A displaying method in a small terminal is provided to perform dithering of decompressed YUV data of a moving image, convert the YUV data into RGB color data, and display an image corresponding to the RGB color data in a small low-resolution terminal. A data conversion table which stores RGB data corresponding to YUV data is generated(S501). Decompressed YUV data of an image to be displayed is read, and the read YUV data is converted into RGB data by using the data conversion table(S509). The image is displayed on a display device by using the converted RGB data(S511). The YUV data is dithered, and the dithered YUV data is converted into the RGB data.

Description

Display Method in Small Terminal

1 is a flowchart illustrating a video decompression and data conversion process in such a terminal.

2 is a flowchart illustrating a screen output method of a conventional terminal.

3 is an exemplary diagram of a data processing apparatus in a small terminal to which the present invention is applied.

4 is a structural diagram of a data conversion table according to an embodiment of the present invention.

5 is a flowchart illustrating a screen output method in a small terminal according to an exemplary embodiment of the present invention.

6 is a flowchart illustrating a process of generating a conversion table for converting RGB data in a screen output method in a small terminal according to an embodiment of the present invention.

7 is a graph comparing data throughput according to output of a video screen according to an embodiment of the present invention and the prior art.

 Explanation of symbols on the main parts of the drawings

301: decompression unit 302: intermediate buffer

303: data conversion unit 304: database (DB)

400: data conversion table

The present invention relates to a screen output method in a small terminal, and in particular, a method for dithering YUV data in a small low resolution terminal and converting it into RGB data corresponding to the resolution of a final screen output device and outputting the screen to a screen. It is about.

In general, in order to output a video from a terminal, a decompression process of decompressing a compressed video and a data conversion process of converting data to display the decompressed video on a screen output device (for example, an LCD monitor) are required. do.

1 is a flowchart illustrating a video decompression and data conversion process in such a terminal. Referring to FIG. 1, when the terminal receives compressed video data (S101), the terminal decompresses the video data (S103) and temporarily stores the compressed video data in an intermediate buffer (S105). Subsequently, the YUV data of the decompressed video is read from the intermediate buffer, converted into RGB data (color value data) for the screen output device (S107), and the RGB data is transmitted to the screen output device to display the video on the screen. To output (S109).

As described above, the data conversion process (S107) for the screen output device converts YUV data resulting from the decompression process (S103) for the video into RGB data, and adjusts the screen brightness or contrast by adjusting the hue, brightness, saturation, etc. To adjust the resolution of the screen output device. The YUV data is expressed in three types of information: the luminance signal (Y), the difference between the luminance signal and the red component (U), and the difference between the luminance signal and the blue component (V). The Y component is error sensitive, so it codes more bits than the color components U and V, and the ratio Y: U: V is usually 4: 2: 2. In general, the equation for converting RGB data to YUV data is Y = 0.3R + 0.59G + 0.11B, U = (BY) x0.493, V = (RY) x0.877. The formula is R = Y + 0.956U + 0.621V, G = Y + 0.272U + 0.647V, B = Y + 1.1061U + 1.703V. In other words, it is determined to be color information insensitive to light, and is converted to YUV signals.

2 is a flowchart illustrating a screen output method of a conventional terminal.

Referring to FIG. 2, data of one screen of specific video data is read from an intermediate buffer in which decompressed video data is stored (S201). The decompressed video data is YUV data. Thereafter, the YUV data is converted into RGB data using a predetermined conversion equation (S203), and then the color (eg, hue, saturation, brightness, etc.) of the RGB data is adjusted according to the screen output device (S205). After the dithering process for the RGB data whose color is adjusted as described above (S207), the corresponding video is output on the screen of the image output apparatus (S209). If it is determined that the playback of the video is ended (S211), if not, the process proceeds to the step S201 to read data of another screen from the intermediate buffer and continue the subsequent steps. Here, dithering is an attempt by a computer program to mix different colors and produce a similar color when the required color is not available, usually when the browser cannot support the colors defined in the web page. In a color display device or a printing press, the color may appear pink in various gradations depending on the ratio of the red dot and the white dot. This dithering produces an image similar to a halftone image, and is used to increase the realism of computer graphics processing at low resolutions, and to make the contours or diagonal lines that are not smooth and staircase stand out.

In the conventional screen output method, after converting YUV data into RGB data and adjusting the color according to the screen output device by using the converted RGB data, the data is processed in 24 bits until the final screen output device. This caused a lot of load in the small terminal.

In order to solve this problem, various methods have been proposed for the method of converting image data after video decompression process in a small video terminal to improve computational performance in the level of color conversion method and dithering method. However, these existing methods are methods for optimizing or hardwareizing at an individual technology level such as conversion from YUV data to RGB data and dithering. This greatly improved the performance of the individual methods, but the amount of data to be processed up to the final screen output device of the small terminal did not change significantly and there was no overall optimization process. In addition, even though the target performance is achieved through the hardware, the price of the small terminal is increased.

Therefore, in the art, the video screen conversion process is performed software after the video decompression process, while reducing the amount of RGB color data that is processed throughout the video data conversion process for screen output, the video screen optimally in a small terminal There is a need for a method that can output the data.

The present invention has been proposed to meet the above requirements and to solve the conventional problems, and first performs dithering of decompressed YUV data in a small low resolution terminal, and then outputs YUV data from the final screen output device. It is an object of the present invention to provide a screen output method in a small terminal for converting into RGB color data that can be output.

The present invention for achieving the above object, a first step of generating a data conversion table for storing the RGB data for the screen output device corresponding to the YUV data, before outputting the screen to the screen output device in the small terminal; Reading decompressed YUV data with respect to the screen to be output, and converting the read YUV data into corresponding RGB data using the data conversion table; And a third step of outputting a screen from the screen output apparatus using the converted RGB data.

In one embodiment of the present invention, the RGB data is preferably RGB data obtained by dithering YUV data, converting each of the dithered YUV data into corresponding RGB data, and adjusting color to suit the screen output device.

In this case, the color may preferably include at least one selected from hue, lightness, and saturation.

In an embodiment of the present disclosure, the first step may include performing dithering on YUV data; Generating RGB data from the dithered YUV data; And adjusting the color to fit the screen output device using the generated RGB data, obtaining final RGB data, and recording the final RGB data in a data conversion table. Here, after the dithering step, the dithering operation may further include a fourth step of cutting at the resolution for the screen output device using the dithered YUV data.

In an embodiment of the present disclosure, the second step may include cutting the YUV data according to the resolution of the screen output device; And converting into RGB data corresponding to the truncated YUV data using the data conversion table.

In one embodiment of the present invention, the resolution of the screen output device of the small terminal is X bits (X = 4, 8, 12, 16, 20) and the decompressed YUV data is (24-X) bits It is preferable.

In the following, a detailed description of a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, when it is determined that detailed descriptions of related well-known functions or constructions may unnecessarily obscure the subject matter of the present invention, detailed description thereof will be omitted so as not to obscure the subject matter of the present invention. something to do.

3 is an exemplary diagram of a data processing apparatus in a small terminal to which the present invention is applied.

Referring to FIG. 3, the data processing apparatus 300 in the small terminal to which the present invention is applied includes a decompression unit 301, an intermediate buffer 302, a data converter 303, and a database 304. do.

The decompressor 301 receives compressed video data and decompresses it. The decompressed video data is YUV data. The decompressed video data is temporarily stored in the intermediate buffer 302.

The data converter 303 reads YUV data of one screen of video data stored in the intermediate buffer 302 according to a control signal of a controller (not shown) in a small terminal, and stores the data stored in the database 304. The YUV data is converted into RGB data using the conversion table 305. That is, the data converter 303 searches the data conversion table 305 which stores the conversion value of the RGB data for the YUV data in the database 304, and reads the data from the intermediate buffer 302 to the YUV data. The corresponding RGB data is found and the YUV data is converted into RGB data for a screen output device (for example, an LCD monitor) of a small terminal. The number of screens to be read may be variously determined according to the control signal of the controller.

The database 304 stores a data conversion table 305 obtained by converting YUV data into RGB data for a screen output device of a small terminal. Preferably, the data conversion table 305 is installed in the small terminal and implemented to be used by the data conversion unit 303. The data conversion table 305 stores values obtained by converting all YUV data that can be implemented in the small terminal into RGB data. More specifically, in the RGB data stored in the data conversion table 305, dithering is performed on all YUV data that can be implemented in a small terminal, and each YUV data after the dithering is performed using a predetermined conversion equation. After converting the data, the converted RGB data is RGB data in which the color is adjusted to match the screen output device to output the screen. That is, in the present invention, before outputting a screen (eg, a video) from the screen output device of the small terminal to the screen, the dithering process for all the YUV data that can be implemented in the small terminal, the RGB data conversion process of the dithered YUV data, The final RGB data after performing all color adjustment processes for the screen output apparatus using the converted RGB data is stored in the data conversion table 305 in advance, and the data conversion table 305 is installed in the small terminal. Thus, when outputting a screen (especially a video) from the small terminal, the final RGB data corresponding to the decompressed YUV data of the screen is searched in the data conversion table 305 to convert the YUV data into the corresponding final RGB data. And convert the final RGB data to the screen output device.

The color adjustment process means adjusting hue, saturation, brightness, etc. of the converted RGB data to fit the screen output device. This is to output a clearer image and adjusts hue, saturation, brightness, etc. according to a screen output device (eg, an LCD) to output a screen.

In the process of converting the YUV data into RGB data, the YUV data may be converted into final RGB data according to the resolution and color of the screen output device. Such a function may be implemented to be set in advance when the terminal is manufactured. Therefore, if necessary, the data converter 303 may implement a data conversion function, a resolution adjustment function and a color adjustment function in one module.

4 is a structural diagram of a data conversion table according to an embodiment of the present invention.

The data conversion table 400 shown in FIG. 4 is, for example, a data conversion table for a case of supporting 12 bits, that is, 4096 colors. The data conversion table 400 basically stores a value obtained by converting each YUV data that can be implemented in the small terminal of the present invention into RGB data. An index is assigned to each YUV data, and RGB data corresponding to each YUV data is converted by a predetermined conversion equation and recorded in the data conversion table 400. In this case, it should be noted that the data conversion table 400 according to the present invention dithers all the YUV data that can be implemented in the small terminal, converts the YUV data into RGB data using a predetermined conversion equation, and converts the YUV data into RGB data. The final RGB data after adjusting the color to fit the screen output device of the small terminal is recorded. In this case, the final RGB data is RGB data for the screen output device of the small terminal. Thus, when the screen is output from the small terminal, the YUV data read from the screen to be output can be converted into RGB data for the screen output device by using the data conversion table prepared in advance, and output to the screen.

Referring to FIG. 4, when a small terminal to which the present invention is applied supports 4096 colors, for example, 4096 colors represent 12 bits of color, RGB data occupies 4 bits. In addition, since YUV data is converted into RGB data, YUV is also 12 bits, and each bit has 4 bits. As a result, converting RGB data using YUV data results in YUV-> RGB: (4,4,4) bits-> (4,4,4) bits.

In FIG. 4, for example, when the index is 2, when the Y, U, and V data are converted into 4 bits, they are respectively (0, 0, 2), and the R, G, and B data are 4 bits, respectively. (0,6,0)

As described above, in the present invention, the screen is output using the data conversion table, so that the screen output method in the small terminal can be performed through the reference of the data conversion table without arithmetic and logical operations. have.

5 is a flowchart illustrating a screen output method in a small terminal according to an exemplary embodiment of the present invention.

Referring to FIG. 5, before outputting a screen (eg, a video) to a screen output apparatus in a small terminal according to the present invention, data conversion is performed by converting all YUV data that can be implemented in the small terminal into RGB data for the screen output apparatus. A table is generated and installed in the small terminal (S501, S503). In this case, an example of the data conversion table is illustrated in FIG. 4, and the converted RGB data is configured by dithering all YUV data, converting each of the dithered YUV data into corresponding RGB data, and then adjusting the color to match the screen output device. Adjusted RGB data, which is final RGB data to be output to the screen from the screen output device.

Subsequently, data on one of the screens to be output from the small terminal is read from the intermediate buffer 302 (S505). In this case, as described above, the screen data stored in the intermediate buffer 302 is preferably decompressed YUV data.

An index for the read YUV data is generated (S507), and the YUV data is converted into RGB data corresponding to the YUV data to which the index is assigned using the data conversion table (S509). The RGB data converted as described above is final RGB data for a screen output device, and is a final RGB data value after sequentially performing dithering of YUV data, conversion to RGB data, and color adjustment functions according to the screen output device. Therefore, the converted final RGB data is used and output to the screen output device (S511). It is determined whether the playback of the one screen is completed (S513), and if it is not finished, the process proceeds to the step S505 where data of the other screen is read from the intermediate buffer 302 to end the playback of the entire video screen. Repeat the following steps (S505 ~ S513) until.

As described above, the screen output method in the small terminal according to the present invention is characterized by generating a data conversion table that converts YUV data into RGB data and outputs the screen using the RGB data stored in the table. In addition, the data conversion table has another feature of converting and storing the YUV data into RGB data for the screen output device after dithering the YUV data first. In particular, in the present invention, the RGB data stored in the table is another final RGB data whose color is adjusted to fit the screen output device.

6 is a flowchart illustrating a process of generating a conversion table for converting RGB data in a screen output method in a small terminal according to an embodiment of the present invention.

Referring to FIG. 6, first, initial values of Y, U, and V are set to (0, 0, 0) in the data conversion table (S601). After adding 1 to the Y value, the Y, U, and V values are recorded (S603 and S605). Subsequently, it is determined whether the Y value is 255 (S607), and the Y, U, and V values are recorded at that time while the Y value is continuously increased by 1 until the Y value is 255 (S603 to S609). Through the steps S603 to 609, the Y, U and V values are all recorded from (0,0,0) to (255,0,0).

Subsequently, the Y value is set to 0 (S611), 1 is added to the U value, and the Y, U, and V values are recorded (S613, S615). Subsequently, it is determined whether the U value is 255 (S617), and the Y, U, and V values are then recorded while increasing the U value by 1 until the U value is 255 (S613 to S619). As a result, all of the Y, U, and V values from (0, 1, 0) to (0, 255, 0) are recorded through the steps S613 to S619.

Subsequently, the U value is set to 0 (S621), and the Y, U, and V values are all recorded from (0,0,1) to (0,0,255) through the same process as above (S623). ~ S629).

As described above, in the present invention, all the Y, U, and V data are recorded through the steps S601 to S629.

Subsequently, dithering is performed on each of the recorded YUV data (S631), and each dithered YUV data is converted to RGB data using the predetermined conversion equation described above (S633). The color is adjusted to the final screen output device with respect to the converted RGB data (S635). The color adjustment preferably includes hue, saturation, brightness adjustment.

An index is allocated to each YUV data and RGB data corresponding to each YUV data is recorded in the data conversion table (S637).

Through this process, the data conversion table is finally generated. As described above, in the present invention, the screen is output to the data conversion table after performing dithering of YUV data, conversion of YUV data to RGB data, color adjustment for RGB data, etc. Stores the final RGB data for output from the device to the screen.

The YUV data is preferably (24-X) bits. In general, since a small terminal capable of outputting video is equipped with a screen output device having a resolution of 4, 8, 12, and 16 bits, the range of the input YUV value is relatively small. Therefore, even if the conversion table of the RGB data for the YUV data is generated, the capacity for this is not so large. For example, in the case of a small terminal having a 12-bit resolution, even if a table that simply allocates YUV data by (4,4,4) bits is created, the table size has 4096 elements and can be sufficiently accommodated in the small terminal. will be. Therefore, in order to record the RGB values in the table, as shown in FIG. 6, the calculation is performed in advance before outputting the video screen, and the table can be used as a reference to maximize the screen output performance in the small terminal. have.

As described above, in the present invention, the dithering process of the YUV data is performed prior to the RGB data conversion process in the generation of the data conversion table, and the color output is performed from the converted RGB data to improve the screen output performance of the small terminal. It can be maximized.

More specifically, the conventional screen output method illustrated in FIG. 2 converts the decompressed YUV data into RGB data and then adjusts colors to fit the screen output device and outputs them to the screen. That is, the decompressed YUV data is converted into color values for the screen output device, that is, RGB data according to the color (saturation, hue, brightness, etc.) set by the user. The RGB data conversion requires 24 times of addition and logic operations, although several simplified conversion equations exist because 24 bits of YUV data are inputted to output 24 bits of RGB data. Subsequently, the screen is output after the process of cutting to the resolution of the final screen output device using the converted RGB value as described above. Since the RGB data is 24 bits until the final screen output, this method requires 24 bits arithmetic and logic operations or additional conversion hardware for high speed to achieve the target performance in small terminals. However, in the screen output method of the present invention, since the YUV dithering process is performed before the RGB data conversion process in advance, there is an advantage that the RGB data need not be processed to 24 bits in the subsequent process.

In addition, when comparing Fig. 2 and Fig. 5, there is no significant difference in the logical process, but in the case of Fig. 5 it is not necessary to maintain the RGB color data at 24 bits until the final screen output step, and for this reason, the image is also adjusted and the RGB data conversion. You can combine the steps into one step.

Further, in the conventional general case, dithering is performed in the final screen output step, which is a step visible to the user as shown in FIG. 2, but the present invention is performed before the RGB color data conversion process. In this case, conventionally, after dithering, the RGB color data values are cut at the resolution for the final screen output device. However, in the present invention, since the dithering process is performed first, only the dithering operation is performed without cutting. If the RGB color data values are cut during dithering according to the conventional method, there is a possibility that serious distortion may occur inevitably during RGB data conversion or resolution adjustment. For this reason, in the present invention, only dithering is performed without cutting. In one embodiment of the present invention, the dithering of the YUV data may preferably use a dithering technique using only its own RGB color data values and coordinate values among various dithering techniques. For example, the ORDERED dithering method may be used as a representative method.

In addition, the conversion of the RGB data is performed before the color adjustment step to play an important role in the overall image quality and performance. This part is divided into two parts. The first is the first process of cutting the Y, U, and V data as necessary for the resolution of the final display device, and the first to obtain the R, G, and B data. 2 courses. At this time, when converting the RGB data, the RGB color data conversion is performed using a simplified conversion equation according to the conventional method shown in FIG. However, in the present invention, after converting the RGB color data, RGB data conversion is performed using YUV data which has already been dithered without dithering as before, and after such RGB color data conversion, only the color correction is performed. There is no need to do it. In other words, the RGB data values in the final screen output step need only be obtained at the resolution of the screen output device. Therefore, even if the calculation is performed after modifying the conversion equation so as to obtain the desired resolution in the conversion equation from YUV data to RGB data, it has the same effect as 24 bits. For example, if the resolution of the final screen output device is 12 bits (4096 colors), when the equation for obtaining R is R = F (Y, U, V), the RGB data conversion equation must cut to 12 bits resolution after RGB data conversion. Therefore, R / 4096 = F (Y, U, V) / 4096. Here, the RGB color data conversion function F can be converted into F (Y, U, V) / 4096 = F (Y / 4096, U / 4096, V / 4096) as a simple multiplication and addition expression.

In summary, when the resolution of the screen output device is X bits color during RGB data conversion, R / 2 ^ (24-X) = F (Y / 2 ^ (24-X), U / 2 for R ^ (24-X), V / 2 ^ (24-X)). In this case, ^ is an exponent symbol, and G and B are the same. In this conversion equation, if the feature of cutting after RGB data conversion is 24bits YUV data is converted to (24-X) bits YUV data, it is applied to RGB data conversion equation.

As described above, as the RGB data conversion process is performed, the amount of data to be processed in a subsequent process for outputting the screen in the small terminal is reduced as shown in FIG. 7.

7 is a graph comparing data throughput according to output of a video screen according to an embodiment of the present invention and the prior art. Referring to FIG. 7, in the conventional method (dotted line display), the data is reduced to the resolution of the output device only when it comes to the final screen output stage. However, in the method according to the present invention, the data is reduced to the final resolution from the previous stage. In the subsequent data processing, the amount of data to be calculated is reduced.

The drawings and detailed description of the invention are merely exemplary of the invention, which are used for the purpose of illustrating the invention only and are not intended to limit the scope of the invention as defined in the appended claims or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

In the present invention as described above, the dithering step is placed at the beginning of the conversion process for the display device, thereby reducing the amount of data to be processed in the remaining parts, and using a conversion table in which color correction, brightness adjustment, and color conversion process are not calculated. By being able to convert, the software in the lightweight terminal can be processed sufficiently in the lightweight terminal.

Claims (7)

Generating a data conversion table for storing RGB data for the screen output device corresponding to the YUV data before outputting the screen to the screen output device in the small terminal; Reading decompressed YUV data with respect to the screen to be output, and converting the read YUV data into corresponding RGB data using the data conversion table; And A third step of outputting a screen from the screen output device using the converted RGB data; Screen output method in a small terminal comprising a. The method of claim 1, wherein the RGB data, Dithering YUV data, converting each of the dithered YUV data into corresponding RGB data, and adjusting the color according to the screen output device. The method of claim 2, wherein the color is, Screen output method in a small terminal, characterized in that it comprises at least one selected from hue, brightness, saturation. The method of claim 1, wherein the first step, Performing dithering on YUV data; Generating RGB data from the dithered YUV data; And Using the generated RGB data, adjusting color to match the screen output device, obtaining final RGB data, and writing the final RGB data to a data conversion table; Screen output method in a small terminal comprising a. The method of claim 4, wherein after performing the dithering, And a fourth step of cutting at the resolution for the screen output device using the dithered YUV data. The method of claim 1, wherein the second step, Cutting the YUV data according to the resolution of the screen output device; And Converting to RGB data corresponding to the truncated YUV data using the data conversion table; Screen output method in a small terminal comprising a. The method of claim 1, In the small terminal, the resolution of the screen output device of the small terminal is X bits (X = 4,8,12,16,20) and the decompressed YUV data is (24-X) bits. How to print the screen.

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