JPH07322306A - Test chart - Google Patents

Abstract

PURPOSE:To enable tests such as the picture quality evaluation of a high definition television or the like using a conventional test chart by plotting a chart for supplying frequency characteristics in a chart part. CONSTITUTION:This chart is constituted of the chart part 1 for which a picture frame 11 provided with the aspect ratio of 4:3 for instance is plotted and a chart peripheral part 2 for which the picture frame 21 provided with the aspect ratio of 16:9 is plotted. The picture frame 11 provided with the aspect ratio of 4:3 is plotted at the center of the picture frame 21 provided with the aspect ratio of 16:9. Also, in the chart part 1, the test chart for supplying the certain frequency characteristics is plotted. Then, the chart plotted in the chart part 1 at the center of the chart peripheral part 2 supplies the frequency characteristics. Further, the picture frame provided with a second aspect ratio corresponding to at least one frequency conversion ratio and plotted in the chart peripheral part 2 performs frequency conversion and supplies at least one frequency characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test chart used for evaluation of image pickup devices of televisions, image quality evaluation, etc., and particularly used for evaluation of image pickup devices of high definition televisions The present invention relates to a suitable test chart.

[0002]

2. Description of the Related Art Today, in research and development and operation of high-definition television, for example, research and development of test charts for evaluating image-capturing devices and image quality of high-definition television (hereinafter referred to as HDTV) are under way. Has been.

The test charts used in the above HDTV (hereinafter referred to as HDTV test charts) are ITE high definition resolution charts, ITE high definition registration charts, I
There are four types of ITE high-definition standard image test charts for TE high-definition grace scale chart and image quality evaluation / test. These 4 types of test charts are based on the high definition studio standard, and
The aspect ratio of each type of test chart is 16: 9.

Here, the current standard system, for example, NTS
In C-type and PAL-type televisions, there are many test charts in addition to the above four types of test charts. For example, there are a circular zone plate chart (hereinafter referred to as CZP) for checking the characteristics of the optical filter shown in FIG. 9, an inmega chart for measuring the frequency characteristics of each portion shown in FIG. Such CZP, Inmega Chart, etc. are also necessary for evaluating HDTV.

Therefore, for example, the above-mentioned FIG.
A case of newly creating the CZP shown in will be described. Here, the CZP will be described in detail.
It is a two-dimensional chart in which the frequency sweeps linearly, and when the Fourier transform is considered, the two-dimensional frequency response of the imaging device can be directly viewed on the screen. Therefore, from this, the characteristics of the optical filter can be checked.

[0006] First, the radius of the basic equation of the circle of CPZ, the radius r _O of the n-th circle n, the center circle, with a radius r _n of the n-th ^{_{circle, r n 2 = nr O 2}} ··· Equation 1 is obtained. Black and white, alternating between these circles
A CZP chart can be created by filling in black and white.

Here, the size of the HDTV test chart has an aspect ratio of 16: 9, a length of 153 mm, and a width of 27.
It is 2 mm. From this, in order to set the maximum vertical resolution of CZP to 1100 TV books (hereinafter referred to as TV books), the width of the circle needs to be 153 / 1100≈0.139 mm. The radius of the outermost circle is 153/2 = 76.5 mm.

Therefore, using the above equation 1, the equation of 76.5 = r _O √m ... The width of the circle (= 0.139 mm)
Is determined by the difference between m and (m-1), and thus the width of the circle can be expressed by using the above equation 1, r _m- r _m-1 = 0.139 = r _O √m-r _O √ (m -1) ... The formula 3 is obtained. When the radius r _{O of the} central circle and the number m of the circles in the chart are calculated by solving the above Formulas 2 and 3, r _O = 4.61 mm m = 275.43. Here, since the number m of circles in the chart is an even number, the number m of circles in the chart is m = 276.

Further, the radius r _O (=
4.61 mm) and Equation 1 above, the radius r _{n of} each circle is expressed as r _n = 4.61√n.

Therefore, in the HDTV test chart, the radius r _{O of the} central circle is 4.61 mm and the radius r _{n of} each circle is (4.61√n) mm.

Here, the radius of the outermost circle in the lateral direction is 272/2 = 136 mm. As described above, the radius r _{n of} each circle is (4.61).
Since it can be expressed as √n) mm, the number of circles n to the outermost circle in the lateral direction is calculated as follows: 136 = 4.61√n n ≈870

The width of the outermost circle in the lateral direction is 870.
Since it is determined by the difference in th circle r ₈₇₀ and 869 th circle r _{8 69,} using the above equation 1, when determining the width of the _{circle, r 870 -r 869 = 4.61 (} √870-√869 ) = 0.078 mm.

Therefore, since the horizontal length of this HDTV test chart is 272 mm and the aspect ratio is 16: 9, the resolution in the outermost circle is (272 / 0.078) × (9/16) = 1961.5
It becomes a TV book.

Further, when the resolution at the center is obtained in the same manner as the resolution at the outermost circle, it is 153 / (4.61 × (√2-1)) = 80 TV lines.

[0015]

However, the chart may be created based on the specifications calculated as described above, but the chart designed as described above can be output with the resolution of a commercially available printer. There wasn't. Alternatively, when the chart size was increased to 3.556 m × 2.000 m for output, black circle toner bleeded into the white circle portion, and printing could not be performed.

As described above, it is very difficult to newly create a CZP dedicated to HDTV, an Inmega chart, or the like.

Alternatively, if an attempt is made to use the test chart of the current television as a test chart for HDTV, the aspect ratio of the current television is 4: 3 and the aspect ratio of HDTV is 16: 9. However, due to the difference in aspect ratio, it cannot be used as it is as a test chart for HDTV. For example, the above-mentioned CZP, which is a frequency-related test chart, has 450 TV lines in the vertical direction and 600 lines in the horizontal direction for a current television.
It is designed with the resolution of TV books. That is, conventional C
ZP could give only one kind of frequency characteristic for the current television. Therefore, HDTV
It was not possible to use it as it was because the frequency was insufficient to use it as a business.

Therefore, the present invention has been made in view of the above-mentioned conventional circumstances, and has the following objects.

That is, an object of the present invention is to provide a test chart which can be used for a test such as image quality evaluation of a high definition television by using a conventional test chart.

Another object of the present invention is to provide a test chart capable of giving at least two kinds of frequency characteristics with one test chart.

[0021]

In order to solve the above problems, a test chart according to the present invention has a chart part in which an image frame having a first aspect ratio is drawn and at least one frequency conversion ratio. A chart peripheral portion in which an image frame having a corresponding second aspect ratio is drawn;
The image frame having the aspect ratio of is drawn in the center of the image frame having the second aspect ratio, and the chart portion is drawn with a chart giving frequency characteristics.

The test chart according to the present invention is characterized in that a circular zone plate chart is drawn in the chart portion.

The test chart according to the present invention is characterized in that an inmega chart is drawn in the chart portion.

[0024]

In the test chart according to the present invention, the chart drawn in the central chart portion in the peripheral portion of the chart gives frequency characteristics. An image frame having a second aspect ratio corresponding to at least one frequency conversion ratio drawn on the peripheral portion of the chart is subjected to frequency conversion to give at least one frequency characteristic.

Further, in the test chart according to the present invention,
A circular zone plate chart is drawn in the chart section.

Further, in the test chart according to the present invention,
An Inmega chart is drawn in the chart section.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the test chart according to the present invention includes, for example, a chart portion 1 in which an image frame 11 having an aspect ratio of 4: 3 is drawn and an image frame having an aspect ratio of 16: 9. 21 and a peripheral portion 2 of the chart.

Picture frame 1 having an aspect ratio of 4: 3 above
1 is drawn in the center of the image frame 21 having the aspect ratio of 16: 9. Further, a test chart giving a certain frequency characteristic is drawn in the chart section 1.

For example, in the test chart according to this embodiment, a conventional test chart can be attached to the chart section 1.

Here, the conventional test chart has a vertical length of 239 mm and a vertical resolution of 450 TV lines. When converting the vertical resolution at an aspect ratio of 16: 9 into 1200 TV lines, if a size corresponding to the conversion ratio (1200: 450) of the conventional test chart to the vertical resolution is obtained, the length is 639.6 mm × width 1137. It will be 1 mm.

As a result, the size of the image frame 21 having the aspect ratio of 16: 9 can be determined from the conventional test chart giving the frequency characteristic corresponding to the vertical resolution of 450 TV lines, to the frequency characteristic corresponding to the vertical resolution of 1200 TV lines. To obtain a height of 639.6 mm x width of 1137.1 m
It has become m.

For example, as shown in FIG. 2, a case where a conventional CZP is attached to the chart portion 1 will be described below. In the test chart shown in FIG. 2, the same components as those in the test chart shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The conventional CZP has a vertical length of 450 T as described above.
It is designed with a resolution of V lines and 600 TV lines horizontally.
First, the widths of the outermost circles in the vertical and horizontal directions of the conventional CZP are obtained.

First, since the vertical resolution is 450 TV lines and the vertical length is 239 mm, the vertical circle width is 239 / 450.apprxeq.0.531 mm.

The radius of the outermost circle is 239/2 = 119.5 mm.

Therefore, from the above formula 1, it can be expressed as follows: 119.5 ² = nr _O ² 119.5 = r _O √n.

The width of the circle (= 0.531 mm) is n
Because determined by the (n-1) difference, to represent the width of the circle using Equation 1 _{above, r n -r n-1 =} 0.531 = r O √n-r O √ (n-1 ) ... The formula 5 is obtained. When the radius r _{O of the} central circle and the number n of the circles up to the outermost circle in the vertical direction are obtained by solving the above Formulas 4 and 5, r _O = 11.254 mm n ≈112.75. Here, since the number n of the circles is an even number, therefore, m = 112.

From the above, when the width of the outermost ring in the vertical direction is obtained, r ₁₁₂ -r ₁₁₁ = 11.254 x (√112-√111) = 0.5330 mm.

Further, since the radius of the outermost circle in the lateral direction is 319/2 = 159.5 mm, using the above equation 1, 159.5 ² = 11.2554 ² n 159.5 = 11.2554 Therefore, the number n of circles up to the outermost circle in the lateral direction is n = 200.87. Here, since the number n of the circles is an even number, m = 200.

From the above, when the width of the outermost ring in the lateral direction is obtained, r ₂₀₀ -r ₁₉₉ = 11.254 x (√200-√299) = 0.3984 mm.

Here, the conventional C designed as described above is used.
In order to use ZP in the aspect ratio of 16: 9, the size of each picture frame for obtaining the frequency characteristic corresponding to each vertical resolution is obtained from the test chart giving the frequency characteristic corresponding to the above 450 vertical TV lines. .

For example, if the size of the image frame for obtaining the frequency characteristic corresponding to the vertical resolution of 1200 TV lines is calculated,
First, the width of the outermost circle in the vertical direction is 0.5 as described above.
Since it is 330 mm, the vertical length is 0.5330 × 1200 = 639.6 mm. Further, since the aspect ratio is 16: 9, the lateral length is 639.6 × 16/9 = 1137.3 mm.

The horizontal equivalent resolution of this size is the width (= 0.39) of the outermost ring in the horizontal direction obtained above.
84 mm), 1137.3 / 0.3984 × 9/16 = 1605.9
It becomes a TV book.

Based on this calculation, the image frame 21 of the test chart shown in FIG. 2 has a vertical length of 639.6 mm as described above.
B. It is drawn in a size of 1137.1 mm in width.

Similarly, when the size of the image frame for obtaining the frequency characteristic corresponding to the vertical resolution of 1100 TV lines is obtained, since the width of the outermost circle in the vertical direction is 0.5330 mm, the vertical length is 0.5330 × 1100 = 586.3 mm. Since the aspect ratio is 16: 9, the horizontal length is 586.3 × 16/9 = 1042.3 mm.

The horizontal equivalent resolution of this size is 1042.3 / 0.3984 × 9/16 = 1471.6.
It becomes a TV book.

Therefore, in the test chart shown in FIG. 2, the image frame 22 for obtaining the frequency characteristic corresponding to the vertical resolution of 1100 TV lines is 586.3 mm in length × 104 in width.
It is drawn on the peripheral portion 2 of the chart with a size of 2.3 mm.

The above vertical resolution of 1200 TV lines, 110
0TV book, vertical resolution 100 TV book, 90
Also in the case of 0 TV lines, 800 TV lines, and 600 TV lines, the size of each image frame is obtained, and the image frame 2 of the determined size is obtained.
3 to image frame 26 are drawn on the peripheral portion 2 of the chart.

As described above, since the image frames 21 to 26 having the aspect ratio of 16: 9 corresponding to the frequency conversion ratio are drawn, the frequency can be changed by changing these image frames using the conventional test chart. The conversion can be done. That is, one CZP for HDTV can give various kinds of frequency characteristics.

In this HDZ CZP, the optical filter is evaluated, for example, as shown in FIGS. In the case without the filter shown in FIG. 3 and the case with the two filters shown in FIG. 4, the alias appears in the pixel pitch portion almost in accordance with the theory, and the signal and the moire due to the folding signal of the sampling frequency. Is appearing. On the other hand, in the case of the three-piece filter shown in FIG. 5, the level of the folding signal as described above is low, and it can be seen that the signal is suppressed by the three-piece filter.

Therefore, as described above, the CZP for HDTV
No particular adverse effects were observed in the evaluation using. Therefore,
The above CZP for HDTV can be sufficiently put into practical use.

Next, as shown in FIG. 6, a case where an Inmega chart is attached instead of CZP in the test chart shown in FIG. 2 will be described below. In the test chart shown in FIG. 6, the same components as those in the test chart shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

First, in the existing system, for example, the NTSC system, the resolution per 1 MHz is 79.2000 TV lines. Here, since the aspect ratio of the conventional test chart is 4: 3, the resolution per 1 MHz is 79.
When 2000 TV books are made to correspond to the conventional test chart, as shown in FIG.
4/3 = 105.6 TV books.

Here, an image frame having an aspect ratio of 16: 9 is
Horizontal 10 with respect to the above 1 MHz test chart
When it is adjusted to 5.6 TV lines, the upper and lower regions 30 are chipped as shown in FIG.

Therefore, first, in HDTV, the resolution per 1 MHz is 29.0909 TV lines. Also, H
Since the aspect ratio of DTV is 16: 9, when the resolution of 29.0909 TV lines per 1 MHz is made compatible with HDTV in the same manner as the above-mentioned conventional test chart, it becomes 29.0909 × 16 / 9≈51.7172 TV lines. There will be.

From the above, when the HDTV frequency corresponding to 1 MHz of the conventional test chart is obtained, it becomes 105.6 / 51.7172≈2.0419 MHz.

Therefore, since the frequency band in the conventional Inmega Chart is 0.5 MHz to 6 MHz, using the above, 0.5 × 2.0419 = 1.0209 MHz 6 × 2.0419 = 12. 2514 MHz, which corresponds to a frequency band of 1.0209 MHz to 122514 MHz in HDTV when the horizontal direction is adjusted.

Here, the frequency conversion in the case of using the picture frame 21 of 1200 TV lines of vertical resolution shown in FIG. 6 will be described.

Since the vertical resolution in the conventional test chart is 450 TV lines, the horizontal resolution is 450 × 4/3 = 600 TV lines using the aspect ratio of 4: 3.

On the other hand, the picture frame 2 of the above-mentioned resolution 1200 TV lines
Since 1 has an aspect ratio of 16: 9, there are 1200 × 16/9 = 2133.3 TV lines in the horizontal direction.

Therefore, when these are compared, 2133.3 / 600 = 3.5556, that is, the image frame 21 with an aspect ratio of 16: 9 is 3.5556 times as large as the chart with an aspect ratio of 4: 3. .

As described above, the frequency of the HDTV when the image frame of the HDTV is horizontally aligned with the conventional test chart of 1 MHz is 2.0419M.
Since it is Hz, the frequency of the image frame 21 corresponding to 1 MHz of the conventional Inmega Chart is 2.0419 × 3.5556 = 7.26000 MHz.

Therefore, the frequency band in the picture frame 21 is 0.5 × 7.26000 = 3.6300 MHz 6 × 7.26000 = 43.5600 MHz, which is 3.6300 to 43.5600 MHz.

As for the image frames 22 to 26, the above-mentioned image frame 2
When the frequency band is obtained in the same manner as in 1, the vertical resolution 11
The frame 22 of 00 TV lines is 3.327 MHz to 39.9.
Picture frame 23 with 300 MHz and vertical resolution of 1000 TV lines
Is 3.025 MHz to 36.300 MHz, and the image frame 24 of vertical resolution 900 TV lines is 2.722 MHz to 3
Picture frame 25 with 2.670 MHz and vertical resolution of 800 TV lines
Is 2.420 MHz to 29.039 MHz, and the image frame 26 of 600 TV lines of vertical resolution is 1.815 MHz to 2
It becomes 1.780 MHz.

Therefore, as described above, the frequency characteristic of the HDTV can be tested using the conventional Inmega chart. Further, by changing the image frames 21 to 26, it is possible to give various kinds of frequency characteristics with one test chart.

[0067]

In the test chart according to the present invention, the chart drawn in the central chart portion around the chart is
Gives frequency characteristics. An image frame having a second aspect ratio corresponding to at least one frequency conversion ratio drawn on the peripheral portion of the chart is subjected to frequency conversion and at least 1
Gives two frequency characteristics. As a result, tests such as image quality evaluation of high definition television can be performed using the conventional test chart. Further, at least two kinds of frequency characteristics can be given by one test chart.

Further, in the test chart according to the present invention,
A circular zone plate chart is drawn in the chart section. As a result, tests such as image quality evaluation of high definition television can be performed using the conventional circular zone plate chart.

Further, in the test chart according to the present invention,
An Inmega chart is drawn in the chart section. As a result, tests such as image quality evaluation of high definition television can be performed using the conventional Inmega chart.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a test chart of an example according to the present invention.

FIG. 2 is a diagram when a conventional circular zone plate chart is used for the test chart.

FIG. 3 is a diagram showing a state without a filter when the characteristics of the optical filter are evaluated using the test chart shown in FIG.

FIG. 4 is a diagram showing a state of a two-sheet filter when the characteristics of the optical filter are evaluated using the test chart shown in FIG.

FIG. 5 is a diagram showing a state of a three-sheet filter when the characteristics of the optical filter are evaluated using the test chart shown in FIG.

6 is a diagram when a conventional Inmega chart is used for the test chart shown in FIG.

FIG. 7 is a diagram showing a 1 MHz chart in the NTSC system.

FIG. 8 is a diagram showing a state where the HDTV is aligned in the horizontal direction with respect to the chart of 1 MHz in the NTSC system.

FIG. 9 is a view showing a conventional circular zone plate chart.

FIG. 10 is a diagram showing a conventional Inmega chart.

[Explanation of symbols]

 1 Chart Part 2 Chart Peripheral Part 11 Image Frame with Aspect Ratio 4: 3 21 Image Frame with Aspect Ratio 16: 9

Claims (3)

[Claims] 1. A chart part having a picture frame having a first aspect ratio and a chart peripheral part having a picture frame having a second aspect ratio corresponding to at least one frequency conversion ratio. The image frame having the first aspect ratio is drawn in the center of the image frame having the second aspect ratio, and the chart portion is drawn with a chart giving frequency characteristics. And a test chart. 2. The test chart according to claim 1, wherein a circular zone plate chart is drawn on the chart portion. 3. The test chart according to claim 1, wherein an inmega chart is drawn on the chart portion.