JP2003279485A - Dazzle evaluation device for antidazzle film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute accurate quantitative evaluation of dazzle in mounting an antidazzle film on a high-precision image display device. <P>SOLUTION: The purpose is accomplished by providing this dazzle evaluation device for an antidazzle film characterized by comprising: a lattice pattern formed on a luminescent surface of a light source; the antidazzle film mounted on the lattice pattern; a photographing means for photographing light from the light source through the lattice pattern and the antidazzle film; and an image data processing means for computing Fourier transform of image data obtained by photographing the light by the photographing means, and thereafter outputting it as a spectrum formed by removing a bright line corresponding to the lattice pattern or by applying a predetermined process to the spectrum. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-glare method for quantitatively evaluating the glare of an antiglare film mounted on the surface of a display device in order to prevent the glare of various image display devices. The present invention relates to a glare evaluation device for glare film. 2. Description of the Related Art Conventionally, as an image display device, a CRT is used.
(Cathode Ray Tube), liquid crystal display devices, plasma displays, and the like are known. In these image display devices, there are cases in which a good image cannot be obtained due to the reflection of external light such as the face of a person watching the display screen or sunlight or fluorescent light. Therefore, in order to suppress the reflection of external light and obtain a good image, it is considered to attach an antiglare film to the display screen. This anti-glare film
For example, the surface of a transparent resin film is subjected to a roughening treatment to form a fine uneven surface, and external light is scattered and reflected to prevent reflection of external light. As the transparent substrate of the antiglare film, a resin such as polyethylene terephthalate is used, and as a method of forming fine irregularities on the surface, for example, a sandblasting method, an embossing method, an etching method or other roughening method, a transparent particle Examples thereof include a resin coating method. Although an anti-glare film can be attached to the display screen, the reflection of external light can be suppressed to some extent, but the pixel size has been reduced and the screen has been flattened due to recent high-definition images. Along with the increase in size of the screen, the interference between the pixels and the light caused by the fine unevenness of the anti-glare film causes a moire image interference fringe, resulting in a glare phenomenon that makes the image rough and difficult to see. In order to suppress the glare of the glare image in which the glare phenomenon occurs as described above, some proposals have been made heretofore. However, conventionally, the evaluation of the glare has been made by using the standard deviation of the luminance variation. It was. That is, the light emission surface was made to emit light uniformly, the luminance distribution on the surface of the antiglare film was measured, and the measured value was statistically processed to obtain the standard deviation. This standard deviation serves as a standard for the magnitude of the luminance variation, and the smaller the standard deviation, the more preferable it is from the viewpoint of preventing glare. However, in the conventional method of evaluating the glare using the standard deviation of the luminance variation, the lattice itself included in the display screen is included as the luminance variation. Therefore, there is a problem that sufficient accuracy cannot be obtained as a quantitative evaluation value of glare corresponding to visual evaluation. FIG. 6 shows, for example, the relationship between the calculated standard deviation of luminance variation and the order of visual evaluation of the glare of each sample for five samples (samples 1 to 5) of the antiglare film. Show. In FIG. 6, sample 1 is marked with ●, sample 2 with ▲, and sample 3
Is represented by ■, sample 4 is represented by x, and sample 5 is represented by +. FIG. 6 shows the rank of each sample, with the horizontal axis representing the visual rank and the vertical axis representing the standard deviation (RMS). As shown in FIG. 6, it can be seen that the ranking by human eyes does not correspond to the ranking by the standard deviation of the luminance variation. If this is expressed in a table in an easy-to-understand manner, it is as shown in Table 1 below. When evaluating with the standard deviation, the smaller the standard deviation, the less the luminance variation, the more the glare is suppressed, and the higher the ranking. So, for example,
Sample 4 has a high ranking of 2nd by standard deviation, although the visual ranking is low at 4th. [Table 1] As described above, the ranking evaluated in ascending order of the standard deviation of the luminance variation does not coincide with the visual ranking, and there is a problem that high accuracy evaluation of glare cannot be made with the standard deviation. The present invention has been made in view of the above-described conventional problems, and performs high-precision quantitative evaluation of glare in a glare image generated when an antiglare film is attached to a high-definition image display device. An object of the present invention is to provide a glare evaluation apparatus for an antiglare film that can be used. In order to solve the above-mentioned problems, the present invention provides a lattice pattern provided on the light emitting surface of a light source, an antiglare film mounted on the lattice pattern, and
An imaging unit that images the light from the light source through the lattice pattern and the anti-glare film, and a bright line corresponding to the lattice pattern portion after Fourier transform of image data obtained by imaging by the imaging unit An anti-glare film glare evaluation apparatus comprising an image data processing means for outputting a spectrum obtained by removing or removing the spectrum and performing a predetermined process on the spectrum. Further, as the predetermined processing to be performed on the spectrum, it is preferable to fit the spectrum with an n-order function. Alternatively, it is preferable to calculate a value obtained by multiplying the function by the MTF function of the visual system and integrating the function. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A glare evaluation apparatus for an antiglare film according to the present invention will be described below in detail with reference to preferred embodiments shown in the accompanying drawings. FIG. 1 is a schematic diagram showing an outline of an embodiment of an antiglare film glare evaluation apparatus according to the present invention. In FIG. 1, the glare evaluation apparatus 10 of this embodiment.
The image capturing means 20 and the image capturing means 20 for capturing the light from the light source 12 through the light source 12, the lattice pattern 14 disposed on the light emitting surface thereof, the antiglare film 16 mounted on the lattice pattern 14, and the lens 18. And image data processing means 22 for processing the image data acquired in step S4 and outputting data for glare evaluation. The lattice pattern 14 is formed on a transparent substrate made of, for example, glass or film, for example, 120 pixels / inch.
A lattice pattern composed of grid-like black lines arranged at a certain density is formed. Antiglare film 16
Is usually attached to the viewer side of the display screen of the image display device to suppress reflection of external light, and the surface of a transparent resin film or the like is roughened to form a fine uneven surface. Is. Since the lens 18 obtains data corresponding to the visual evaluation, the lens 18 is separated from the light source 12 by an angle phase that is large enough to be seen by the human eye,
It is preferable that the image can be photographed by the image photographing means 20. The image capturing means 20 captures an image and captures the image as digital image data. The image data processing means 22 receives digital image data from the image photographing means 20, and in response to this,
Data processing is performed. Specifically, the received digital image data is subjected to a two-dimensional Fourier transform, and then a spectral value obtained by cutting a bright peak region corresponding to the spectrum of the lattice pattern 14 in the image data is obtained. It is integrated in the X direction and the Y direction and output as data for glare evaluation. The image data processing means 22 may be a dedicated device configured to perform such processing, or may be a personal computer incorporating software for executing such processing. In this way, by cutting the bright lines corresponding to the lattice pattern 14, it is possible to evaluate only the glare that is not affected by the lattice pattern 14, and it is possible to quantitatively evaluate the glare with high accuracy. Hereinafter, the glare evaluation apparatus 10 of this embodiment will be described.
As a function of the above, a method for quantitatively evaluating the glare of the antiglare film using the glare evaluation apparatus 10 will be described. The flow of processing of the present glare evaluation method is shown in the flowchart of FIG. 2, and will be described along this flowchart. In the flowchart of FIG. 2, first, in step 100, the light that has exited from the light source 12 and passed through the lattice pattern 14 and the antiglare film 16 by the image photographing means 20 (for example, a CCD camera) passes through the lens 18. To shoot. At this time, for example, ten images are photographed by shifting the position of the image photographing means 20. Image photographing means 20
The digital image data acquired in step (1) is sent to the image data processing means 22. Next, in step 110, the image data processing means 22 that has received the digital image data performs a two-dimensional Fourier transform on the digital image data to obtain a two-dimensional spectrum. An example of the two-dimensional spectrum thus obtained is shown in FIG. In FIG.
A portion surrounded by a broken line is a bright line-shaped portion corresponding to the lattice of the lattice pattern 14. Also, the white spotted portion in the center of FIG. 3 is the glare component. Therefore, since this bright line-shaped part becomes an obstacle to evaluation of glare, it must be removed. Next, in step 120, the image data processing means 22 cuts the bright lines corresponding to the lattice pattern 14 from the two-dimensional spectrum thus obtained. In the next step 130, the two-dimensional spectrum data from which the bright lines have been removed is integrated in the vertical direction.
One of the purposes of this integration includes the meaning that the smooth spectrum is not obtained even if the position shift is performed 10 times. Here, in this embodiment, it is essential to perform integration by cutting the bright line. FIG. 4 shows a Fourier spectrum on the right side obtained by integrating the horizontal axis with the spatial frequency, the vertical axis with the Fourier spectrum, and integrating in the vertical direction without cutting the bright line. If the integration is performed without removing the bright line portion, the bright line portion remains as indicated by a symbol K in FIG. 4, which affects subsequent glare evaluation, and high-precision evaluation cannot be performed. In step 140, the image data processing means 22 calculates a smooth function by fitting, for example, a predetermined n-order function to the Fourier spectrum obtained by integrating in the vertical direction in step 130. Is output. By comparing the graphs of these functions, quantitative evaluation can be performed with high accuracy as glare spatial frequency characteristics in step 150. At this time, the value of the spectrum obtained by cutting and integrating the bright line is equal to the spectrum obtained by integrating in step 130 without cutting the bright line in step 120, and at least two bright lines excluding the spatial frequency 0 are obtained. 0.5 at the existing spatial frequency
% Or more and less than 10%. Alternatively, at this time, the MTF function (Modulation Transfer Function) of the visual system such as the response function of the eye.
May be multiplied in step 160 to calculate a value obtained by integrating both vertical and horizontal in step 170 and step 180, and may be output as an evaluation value of glare in step 190. By calculating such a value, it is possible to output as a numerical value corresponding to the visual evaluation. A more specific embodiment will be described below. (Embodiment) In the configuration of FIG. 1, FUJICOLOR Viewer 4 × 5 manufactured by Fuji Photo Film Co., Ltd. is used as the light source, the lattice pattern 14 is glass-deposited, and the lens 18 is
NIKON AF Micro Nikkor ED200mm F40 is used, and the image capturing means 20 is a CCD camera (Apogee K1-14E)
Was used. Further, five samples 1 to 5 shown in FIG. 6 were used as the antiglare film. First, 10 samples of each sample 1-5 are photographed by shifting the camera position with a CCD camera using the apparatus having the above-described configuration, and this is converted into a two-dimensional spectrum by two-dimensional Fourier transform. did. Next, the bright line portion corresponding to the lattice pattern was cut and integrated in the vertical direction. Then, for the integrated Fourier spectrum,
An appropriate n-order function was fitted to obtain a smooth function. A graph of this function is shown in FIG. FIG.
The horizontal axis represents the spatial frequency and the vertical axis represents the Fourier spectrum. The graph of sample 1 is indicated by ●, the graph of sample 2 is indicated by ▲, the graph of sample 3 is indicated by ■, the graph of sample 4 is indicated by x, and the graph of sample 5 is indicated by +. In FIG. 5, the lower the graph is (the smaller the value is), the more the glare is suppressed and the higher the evaluation is. Therefore, according to the evaluation by the method of this example, each sample 1 to 1
The evaluation ranking of 5 matches the visual ranking shown in FIG. Furthermore, according to this embodiment, as shown in FIG.
Since the function representing the evaluation is calculated for each sample 1 to 5, it is possible to analyze not only the rank but also the relationship between each sample in detail and perform quantitative evaluation with high accuracy. It becomes. As described above in detail, according to this embodiment, a glare image obtained by photographing light from a light source through a lattice pattern and an antiglare film is obtained by two-dimensional Fourier transform. In addition, the bright line portion corresponding to the lattice pattern is removed from the two-dimensional spectrum image and integrated, and a function obtained by fitting the Fourier spectrum with a predetermined n-order function is output, thereby eliminating the influence of the lattice pattern. Thus, it has become possible to perform quantitative evaluation of glare with high accuracy. At this time, even if a two-dimensional Fourier spectrum is output by integrating the bright lines corresponding to the lattice pattern before fitting with the n-order function, it can be used for evaluating the glare sufficiently. it can. Further, if a value obtained by multiplying and integrating an MTF function such as a response function of an eye is output as an evaluation value, it is almost the same as visual evaluation. In the embodiment described above, the measurement device (from the light source 12 to the image photographing means 22) that captures an image to obtain a glare image and the glare image obtained by capturing the image are received and processed for data. The image data processing means for performing the evaluation is integrated. However, the glare evaluation method may be incorporated into a computer as software that can be executed by a computer, and the portion related to the glare evaluation method may be separated. According to this configuration, for example, a glare image is obtained from an image where a glare image is generated, such as a liquid crystal display device or a plasma display, and the data is input to a computer having a software for glare evaluation method. Quantitative evaluation of such glare can be performed. The glare evaluation apparatus for an antiglare film according to the present invention has been described in detail above, but the present invention is not limited to the above embodiment, and various kinds of devices can be used without departing from the gist of the present invention. Of course, improvements and changes may be made. As described above, according to the present invention, it is possible to carry out quantitative evaluation of glare corresponding to visual evaluation on an antiglare film with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing an outline of an embodiment of a glare evaluation apparatus for an antiglare film according to the present invention. FIG. 2 is a flowchart showing a flow of processing of a glare evaluation method performed by the glare evaluation apparatus of the present embodiment. FIG. 3 is an explanatory diagram showing an example of a two-dimensional spectrum. FIG. 4 is a diagram showing a Fourier spectrum integrated without removing bright lines. FIG. 5 is a diagram showing an example of a glare Fourier spectrum at 125 dpi in the present embodiment. FIG. 6 is a diagram showing a relationship between visual evaluation of glare and evaluation by standard deviation. [Description of Symbols] 10 Glare Evaluation Device for Anti-Glare Film 12 Light Source 14 Lattice Pattern 16 Anti-Glare Film 18 Lens 20 Image Shooting Unit (CCD Camera) 22 Image Data Processing Unit

Claims (1)

1. A grid pattern provided on a light-emitting surface of a light source, an antiglare film mounted on the grid pattern, and light from the light source, the grid pattern and the anti-reflection A photographing means for photographing through a glare film, and a Fourier transform of image data obtained by photographing with the photographing means, and a spectrum obtained by removing a bright line corresponding to the lattice pattern portion or a predetermined value for the spectrum A glare evaluation apparatus for an anti-glare film, comprising: an image data processing means for performing the above processing and outputting the image data.