KR20000051199A - Apparatus for image quality test - Google Patents

Abstract

PURPOSE: An apparatus for testing image quality is provided to test the definition of a screen without using an additional tester by using the system itself. CONSTITUTION: An apparatus for testing image quality includes a test pattern generator(20), a space converter(30), and a look-up table(40). The test pattern generator(20) generates test pattern value for the input image signal or the test pattern value. The space converter(30) converts the color region generated at the test pattern generator into another color region, or bypasses the color region as it is. The look-up table(40) generates various output varied with various rules under the control of a mapped value. The test pattern generator is implemented inside of the receiver system.

Description

Apparatus for image quality test}

The present invention relates to an image quality test apparatus for testing image quality of a monitor, which is an image information output apparatus.

Image test signals are useful for evaluating image processing systems. One use is to set up and adjust TV monitors. The most suitable and simple way to evaluate an imaging device is to use a stable test signal of known characteristics.

The current method of testing video signals takes the form of connecting another piece of equipment, a test pattern generator, to the input of the video system and observing it at the output.

If distortion occurs, the display device adjusts to remove or minimize it. Otherwise, the defective part must be replaced or repaired.

In addition, if the system can correctly pass the test signal, the video signal will also be clear. The test pattern generator generates the signals needed for such a test.

However, these existing schemes require additional equipment, called test pattern generators, to perform some simple tests.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image quality test apparatus that can perform a test for monitor image quality evaluation in a system without a separate test pattern generator.

Another object of the present invention is to provide an image quality test apparatus that generates various types of test patterns by inserting a test pattern generator into a system.

Another object of the present invention is to provide an image quality test apparatus for generating a test pattern converted into various rules by adjusting a calculation coefficient using a lookup table.

1 is a block diagram illustrating an image processing system for testing image quality according to the present invention.

FIG. 2 is a detailed block diagram of the test pattern generator of FIG. 1.

Figure 3 shows an example of each color value of a typical 75% size, 100% saturated NTSC EIA color bar test pattern.

4A-4C show examples of a typical Y colorbar test pattern.

FIG. 5A is a view illustrating a configuration of A-A 'disconnection of the cross test pattern of FIG. 4A

FIG. 5B is a diagram illustrating a configuration of B-B 'disconnection of the cross hatch test pattern of FIG. 4B. FIG.

6A to 6C illustrate examples of changing a thickness of lines of cross and cross hatch test patterns by varying a threshold in the lookup table of FIG. 1.

FIG. 7 illustrates an example of changing a size of a dot test pattern by varying a threshold in the lookup table of FIG. 1.

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

10: image processor 20: test pattern generator

21: test pattern generator 22: multiplexer

30: color space converter (CSC) 40: look-up table

According to an exemplary embodiment of the present invention, an image quality test apparatus includes a test pattern generator that outputs an input image signal or a test pattern value for a test, and a color region that is different from a color region output from the test pattern generator. And a look-up table for generating an output that is changed by various rules from the output of the color space conversion section and the color space conversion section that bypasses or bypasses an area.

The test pattern generator is characterized in that provided in the receiving system.

The test pattern generator outputs a Y / Cb / Cr value corresponding to each pattern, and outputs an NTSC EIA color bar test pattern by outputting a gamma corrected R / G / B value corresponding to the pattern in the look-up table. Characterized in that.

The look-up table may output a single color full field test pattern by setting any one or more of gamma corrected R / G / B values to zero.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

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

The system structure for test pattern generation according to the present invention is shown in FIG.

Referring to FIG. 1, an image signal processor 10 for processing an input image signal through a decoding process, a test pattern generator for bypassing the processed image signal or generating a pattern for a test regardless of an input image. 20, a color space converter (CSC) 30 for converting the color output from the test pattern generator 20, and a YCbCr or RGB value of the CSC 30 is adjusted to various rules. It consists of a look-up table (LUT) 40 which generates the output.

The test pattern generator 20 includes a test pattern generator 21 for generating a test pattern and a multiplexer 22 for selectively outputting an input image signal or an output of the test pattern generator 21.

In the present invention configured as described above, the look-up table 40 may be used for gamma correction or test pattern generation. This is necessary for gamma correction in TVs and the like, but it is not meaningful for monitors such as PCs.

When the image signal output from the image processor 10 is processed in the color space of Y / Cb / Cr, the input image signals pass through the multiplexer 22 of the test pattern generator 20 as it is. It is input to the CSC 30.

At this time, the CSC 30 passes the input Y / Cb / Cr as it is or converts it into a color space of R / G / B and outputs it. Thus, the final system output to the monitor may optionally have a Y / Cb / Cr or R / G / B color space.

The look-up table (LUT) 40 performs arithmetic operations such as gamma correction using monitor characteristics. That is, the input linear R / G / B is output after the gamma correction in the LUT 40 is changed according to the gamma curve. When this is combined with the monitor characteristic function, the pixel values through the original CSC 30 are visually displayed. Will appear.

On the other hand, if the test pattern needs to be generated, the test pattern generator 20 generates a Y / Cb / Cr value corresponding to each pattern from the test pattern generator 21 instead of outputting an input signal, and then multiplexers 22. Output through

The most common test pattern, 75% amplitude and 100% saturation, in the National Television Standards Committee (NTSC) Electronic Industries Association (EIA) color bars. Color space values for each color are shown in FIG. 3.

3, it can be seen that there is a certain rule between the colors for the R / G / B component. That is, it can be seen that if one or more of R / G / B is set to 0 for white, the color can be changed to any color. This is done by making the corresponding output zero through the LUT 40.

As an example, it is assumed that the test pattern generator 20 generates a pattern called a white full field. This may be done so that the pattern generator 20 outputs values of Y / Cb / Cr of 180/128/128, respectively. Then, this value changes to the R / G / B value of 135/135/135 as it passes through the CSC 30, and when the gamma curve is applied to both R / G / B in the LUT 40, 191/191/191 Is output as a gamma corrected R / G / B value, which corresponds to white.

However, when the LUT 40 outputs a gamma curve for R, and 0 unconditionally outputs G and B regardless of an input, it becomes 191/0/0 and becomes red. This can be used in a pattern called red full field. In the same way, you can create colors such as green, blue, and black.

Alternatively, even if the test pattern generator 20 outputs an arbitrary result-irrespective of the actual image data output or any other pattern value-the LUT 40 is applied to a single color defined as Y / Cb / Cr output. If you print only the value for, you can get the same result.

Usually, the red (R), green (G), and blue (B) full fields are used as the most basic test pattern to determine whether any one of the primary colors is causing an error because the monitor consists of these three primary colors. do. Of course, the same effect can also be achieved for the color space of Y / Cb / Cr simply by giving the LUT 40 an appropriate expression.

In this case, there is an EIA color bar and a Y color bar in which only Y values are extracted for a more complex function for the full field which outputs a single color.

If the LUT 40 exports Y / Cb / Cr as it is when the EIA color bar as shown in FIG. 3 is output from the test pattern generator 20, the EIA color bar is finally generated, and only Y is exported to Cb and Cr. Regardless of the input value, the Y color bar appears on the monitor when only the Cb and Cr values of the gray level (white, black, etc.) are exported.

In addition, another pattern used for measuring the monitor image quality includes a cross as shown in FIG. 4A, a cross hatch as shown in FIG. 4B, and a dot as shown in FIG. 4C.

The thicknesses of the patterns may be adjusted by changing the conversion equation in the LUT 40. That is, for the cross and cross hatch patterns of Figs. 4A and 4B, a series of lines are used to form the pattern. In this case, as shown in FIGS. 5A and 5B, the most central portion of each vertical and horizontal lines is assigned to Y, which is the Y value of white, and up to 16, which is the Y value of black, is formed while forming stairs on both sides.

In FIG. 5, the numeral means a Y value, and Cb and Cr values are fixed to 128 for the three patterns.

In this case, consider a case in which the LUT 40 divides pixel values of all ranges into black and white by using an arbitrary threshold value instead of a gamma curve.

For example, after exporting Y / Cb / Cr from the CSC 30 as it is, in the LUT 40, Cb and Cr are processed to be 128, which is a general gray level value as shown in FIG. 6C, and the Y value is as shown in FIG. 6A. Suppose we use 160 as the threshold. Then, only the region having a Y value of 180 that is 160 or more becomes white, and the remaining region becomes black. If the threshold value is reduced to 110, 80, 60, etc., the area included in white increases, thereby increasing the thickness of the line.

In the cross hatch, as shown in FIG. 6B, if only the center of the vertical and horizontal lines is increased more than the rest of the line, the thickness of the lines gradually decreases in the thick hatched cross hatch pattern. In the end, only the middle two lines can be left to create a cross pattern.

The same method can also be used for the dot pattern of FIG. 7 to change the diameter of the white point. This allows testing with thinner lines and dots where more detailed testing is needed. Again, if the LUT 40 function is used properly, the same result can be obtained for R / G / B.

In addition, applications such as the Picture Line-Up Generating Equipment (PLUGE) pattern and the Simpte (SMPTE, Bar Association of Motion Picture and Television Engineers) patterns by adjusting the colors of the EIA color bar area are applied. Possible patterns can be generated in this structure.

As described above, since the test patterns generally share a certain regularity, various types of test patterns can be generated by adding some hardware in the system and appropriately adjusting externally for blocks such as CSC and LUT.

As described above, according to the image quality test apparatus according to the present invention, it is possible to easily test the image quality performance of the display apparatus without any additional equipment in all image processing and output systems including a TV monitor. In addition, by placing the test pattern generator in a proper position in the signal processing structure in the system, higher-level tests other than simple monitor image quality measurement can be performed inside the system.

Claims (10)

A reception system for processing an image signal and displaying the same on a display device, A test pattern generator which outputs an input image signal or a test pattern value for a test; A color space converter for converting or bypassing the color gamut output from the test pattern generator to another color gamut; And a look-up table that generates an output that is changed by various rules from the output of the color space converter by adjusting a mapped value. The method of claim 1, wherein the test pattern generation unit Picture quality test apparatus, characterized in that provided in the receiving system. The method of claim 1, The test pattern generator outputs a Y / Cb / Cr value corresponding to each pattern, and outputs an NTSC EIA color bar test pattern by outputting a gamma corrected R / G / B value corresponding to the pattern in the look-up table. Quality test apparatus, characterized in that. 4. The table of claim 3, wherein the look-up table is And a single color full field test pattern is output by setting any one or more of gamma corrected R / G / B values to zero. The method of claim 1, wherein the look-up table is And a single color full field test pattern is generated by outputting a value for a single color determined as an output of Y / Cb / Cr regardless of the output of the test pattern generator. The method of claim 1, The test pattern generator generates an EIA color bar test pattern, and generates an EIA color bar test pattern by outputting the corresponding Y / Cb / Cr in a look-up table as it is. The method of claim 1, The EIA color bar test pattern is generated by the test pattern generator, and the Y value corresponding to the Y value is output in the look-up table as it is and the Cb / Cr value is output in gray level regardless of the input value. Picture quality test apparatus, characterized in that to generate. The method of claim 1, wherein the look-up table is The image quality test apparatus, wherein the thickness of the vertical and horizontal lines is adjusted by varying the Y threshold value for the cross test pattern. The method of claim 1, wherein the look-up table is The cross hatch test pattern of the image quality test apparatus, characterized in that the thickness of the vertical, horizontal lines are adjusted by varying the threshold of Y. The method of claim 1, wherein the look-up table is An image quality test apparatus, wherein the dot pattern is adjusted by varying a threshold of Y for a dot pattern.