JP7196646B2 - Image display device and inspection method - Google Patents

Description

The present invention relates to an image display device and an inspection method.

For example, in an image display device that displays medical images, it is important whether the gradation level of the image is displayed appropriately. In relation to this, Patent Document 1 discloses a technique of displaying a predetermined contrast pattern so that a user can easily determine the degree of luminance deterioration in an image display device.

However, the reason why gradation levels are not properly displayed is not limited to deterioration of brightness in the image display device. If the input/output characteristics of arbitrary components present in the signal transmission path from the image signal generation source to the image display section have nonlinearity, the nonlinearity causes the gradation level values to deviate from the original gradation level values. An image signal is input to the image display section. If the amount of deviation is minute, it is difficult to grasp the presence of nonlinearity in the input/output characteristics of the signal transmission path just by visually observing the displayed image.

JP-A-2001-34255

According to the technique disclosed in Patent Document 1, it is possible to easily detect the degree of luminance deterioration in an image display device, but it is also possible to easily check the presence or absence of non-linear input/output characteristics in a signal transmission path. can't Therefore, there is a demand for a technology that can easily confirm whether or not there is nonlinearity in the input/output characteristics of a signal transmission path.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image display device and an inspection method that can easily confirm whether there is nonlinearity in the input/output characteristics of a signal transmission path.

An image display device according to the present invention includes an image signal receiving unit that receives an image signal of a pattern image in which N (N is an integer equal to or greater than 2) partial images with different gradation level values are regularly arranged;
a converting section for converting some of the gradation level values included in the image signal according to a predetermined conversion rule; and an image signal converted by the converting section. wherein the gradation level value of the n-th partial image (n is an integer of 1 or more and N or less) among the N partial images is one of N successive gradation levels. The conversion unit converts the n-th gradation level value corresponding to a term of a predetermined arithmetic progression according to the predetermined conversion rule.

Further, in the inspection method according to the present invention, an image signal of a pattern image in which N (N is an integer equal to or greater than 2) partial images with different gradation level values are regularly arranged is received, and Among the gradation level values obtained, some of the gradation level values are converted according to a predetermined conversion rule, and the converted image signals are used to display the N partial images. Among them, the gradation level value of the n-th partial image (n is an integer of 1 or more and N or less) is the n-th gradation level value of the continuous N gradation levels, and in the conversion, a predetermined equal The gradation level values corresponding to the terms of the difference sequence are converted according to the predetermined conversion rule.

According to the present invention, it is possible to provide an image display device and an inspection method that can easily confirm whether there is nonlinearity in input/output characteristics in a signal transmission path.

1 is a block diagram showing an example of a configuration of an image display system according to Embodiment 1; FIG. FIG. 4 is a schematic diagram showing an example of gradation level values and arrangement of partial images in a pattern image composed of 256 types of partial images; 3 is a schematic diagram showing a pattern image configured by arranging the partial images shown in FIG. 2; FIG. 4 is a table showing an example of conversion rules for inspection; FIG. 5 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 2 when nonlinearity does not exist in the signal transmission path; 6 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. 5; FIG. FIG. 5 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 2 in the case where the gradation level value changes due to nonlinearity in the signal transmission path; FIG. 8 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. 7; FIG. 10 is a schematic diagram showing another example of the gradation level values and arrangement of partial images in a pattern image composed of 256 types of partial images; FIG. 10 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 9 when nonlinearity does not exist in the signal transmission path; FIG. 11 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. 10; FIG. 10 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 9 when the gradation level value changes due to nonlinearity in the signal transmission path; FIG. 13 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. 12; FIG. 11 is a schematic diagram showing still another example of the gradation level values and arrangement of each partial image in a pattern image composed of 256 types of partial images; FIG. 15 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 14 when nonlinearity does not exist in the signal transmission path; FIG. 16 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. 15; FIG. 15 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 14 when the gradation level value changes due to nonlinearity in the signal transmission path; FIG. 18 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. 17; Schematic representation of a geometric pattern formed by two regions: a partial image group region whose gradation level value is set to a predetermined value by conversion by a conversion unit and a partial image group region where the original gradation level value is set. It is a diagram. Schematic representation of a geometric pattern formed by two regions: a partial image group region whose gradation level value is set to a predetermined value by conversion by a conversion unit and a partial image group region where the original gradation level value is set. It is a diagram. Schematic representation of a geometric pattern formed by two regions: a partial image group region whose gradation level value is set to a predetermined value by conversion by a conversion unit and a partial image group region where the original gradation level value is set. It is a diagram. Schematic representation of a geometric pattern formed by two regions: a partial image group region whose gradation level value is set to a predetermined value by conversion by a conversion unit and a partial image group region where the original gradation level value is set. It is a diagram. Schematic representation of a geometric pattern formed by two regions: a partial image group region whose gradation level value is set to a predetermined value by conversion by a conversion unit and a partial image group region where the original gradation level value is set. It is a diagram. 4 is a table showing an example of conversion rules for shifting a gradation level value by a predetermined level value; FIG. 25 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 24 is applied to the pattern image shown in FIG. 2 when nonlinearity does not exist in the signal transmission path; FIG. 26 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. 25; gradation level values to be converted that are less than a predetermined threshold are uniformly converted to a predetermined first gradation level value, and gradation level values to be converted that are equal to or greater than this threshold are converted to a predetermined second gradation level 4 is a table showing an example of conversion rules for uniform conversion into values; FIG. 28 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 27 is applied to the pattern image shown in FIG. 2 when nonlinearity does not exist in the signal transmission path; FIG. 29 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. 28; FIG. 11 is a table showing an example of conversion rules according to the second embodiment; FIG. FIG. 31 is a schematic diagram showing a pattern image when the conversion rule shown in FIG. 30 is applied to the pattern image shown in FIG. 2 when there is no nonlinearity in the signal transmission path; 4 is a table showing an example of conversion rules for shifting a gradation level value by a predetermined level value; FIG. 33 is a schematic diagram showing a pattern image when the conversion rule shown in FIG. 32 is applied to the pattern image shown in FIG. 2 when nonlinearity does not exist in the signal transmission path; FIG. 34 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. 33; FIG. 11 is a block diagram showing an example of the configuration of an image display system according to a third embodiment; FIG. 10 is a flow chart showing an example of the operation of the image display system according to the third embodiment;

Before describing the embodiments, first, the matters examined by the inventor will be described.

2. Description of the Related Art When an image signal output from an image signal output device such as a personal computer is displayed on an image display device, the image signal is input to the display section of the image display device via various elements, for example. These elements are, for example, a video card driver of the image signal output device, an output circuit of the video card, a video cable connecting the image signal output device and the image display device, a receiver circuit of the image display device, and a lookup table of the image display device. (hereinafter referred to as LUT (Lookup table)). That is, the image signal input to the display section of the image display device is processed by these elements. In order to appropriately display the gradation level of the image on the display unit, it is required that the input/output characteristics of the gradation processing by these elements have linearity. That is, if non-linearity exists in the gradation processing by any element, the gradation level of the image cannot be displayed appropriately on the display unit.

However, in the display on the display unit, even if an image is displayed with gradation levels that deviate from the gradation level values that should be displayed due to non-linearity, the amount of deviation is so small that the display can only be viewed visually. In general, it is difficult for humans to recognize the occurrence of such events. This will be described with a specific example. Here, it is assumed that the input/output characteristics of the LUT have linearity. At this time, if an image signal with a gradation level value of 50 is processed to make the gradation characteristics non-linear by, for example, an element other than the LUT, the display unit displays 49 or 51, for example. An image signal changed to a gradation level value is input. However, it is difficult to identify such a change just by visually observing the displayed image.

General-purpose digital signal transmission devices such as video cards are often the factors that give non-linearity to the input/output characteristics of gradation levels. If the manufacturer that manufactures the product has grasped the non-linear characteristics of the product by inspecting the product and has specified it as the specification of the product, other manufacturers and end users who use the product , the existence of nonlinearity can be easily grasped. However, such explicit statements are rarely made. Therefore, it is necessary for other manufacturers or end users who use the product to confirm the presence or absence of non-linearity by themselves. When non-linearity is found, it may be necessary to issue an improvement request such as modification of the product to the manufacturer of the product.
However, as mentioned above, it is difficult to visually determine the presence or absence of non-linearity. I had no choice but to check. Therefore, it is desired to implement a technique for easily detecting the presence or absence of nonlinearity on the signal transmission path of the image signal.
Therefore, a technique for easily confirming whether or not there is nonlinearity in input/output characteristics in a signal transmission path will be specifically described below.

<Embodiment 1>
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an example configuration of an image display system 10 according to the first embodiment. As shown in FIG. 1, the image display system 10 has an image signal output device 100 and an image display device 200 . The image signal output device 100 and the image display device 200 are communicably connected by wire or wirelessly.

The image signal output device 100 is a terminal device that outputs image signals to the image display device 200 . For example, the image signal output device 100 is a personal computer, a tablet terminal, a smartphone, or the like, but is not limited to these.

The image display device 200 is a device that displays an image corresponding to the image signal output by the image signal output device 100 on the display unit 203 . The display unit 203 is, for example, a display such as a liquid crystal monitor or an organic EL (Electro-Luminescence) monitor, but may be a projector. The image display device 200 can have any configuration as long as it can display an image. For example, the image display device 200 may be configured as a head-mounted display or a head-up display.

The image signal output device 100 has a non-inspection signal generation unit 101 , an inspection signal generation unit 102 , an image signal output unit 103 , and a conversion rule setting unit 104 .

The non-inspection signal generation unit 101 generates an image signal of an image to be displayed on the image display device 200 during non-inspection, that is, an image to be displayed on the image display device 200 during normal operation of the image display system 10 . For example, when the image display system 10 is used as a medical system, this image is a medical image showing an affected area of a patient, but is not limited to this.

The non-inspection signal generator 101 is, for example, software such as image display software. In this case, the non-inspection signal generator 101 is realized by executing a program including one or more instructions stored in a memory or the like by a processor provided in the image signal output device 100 .

The inspection signal generation unit 102 generates an image signal of an image to be displayed on the image display device 200 during inspection. That is, the inspection signal generation unit 102 generates an image signal of an image for inspecting whether or not there is nonlinearity in the input/output characteristics of the signal transmission path.
In this embodiment, the inspection signal generation unit 102 generates an image signal of a pattern image, which is an image in which N (N is an integer equal to or greater than 2) partial images with different gradation level values are regularly arranged. do. Here, the gradation level of the n-th partial image (n is an integer from 1 to N inclusive) among the N partial images is the n-th gradation level of consecutive N gradation levels.

The continuous N gradation levels are, for example, a series of gradation levels ranging from the lower limit to the upper limit of the displayable gradation level values in the image display device 200 . For example, if the lower limit is 0 and the upper limit is 255, the pattern image is a pattern image in which 256 types of partial images are regularly arranged. In the following description, as an example, the pattern image includes 256 types of partial images with gradation level values from 0 to 255. The range of gradation level values of the partial images included in the pattern image is It does not have to match the range from the lower limit to the upper limit of the gradation level values displayable in the image display device 200 . That is, for example, the range of gradation level values of the partial images included in the pattern image is a predetermined range (for example, 0 to 192, or , 64 to 224, etc.). Also, the lower limit value of the gradation level value does not have to be 0, and the upper limit value does not have to be 255 either.

The lower limit of the gradation level value of the image to be displayed on the image display device 200 during inspection will be referred to as the lower limit inspection gradation level value, and the upper limit will be referred to as the upper limit inspection gradation level value. The pattern image includes N partial images from the partial image with the lower test tone level value to the partial image with the upper test tone level value.

FIG. 2 is a schematic diagram showing an example of gradation level values and arrangement of partial images in a pattern image composed of 256 types of partial images. In the example shown in FIG. 2, the partial images from the lower limit test gradation level value to the upper limit test gradation level value are arranged according to the following rule in order of gradation level. That is, in the example shown in FIG. 2, a predetermined number of images (specifically, 16 partial images each) are horizontally arranged from one end (specifically, the left end) to the other end (specifically, the right end). ) arranging sub-images is repeated vertically. In the embodiment, a square pattern image will be described as an example, but the pattern image may have other shapes.

FIG. 3 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. In the example shown in FIG. 3, a partial image with a gradation level value of 0, i.e., a partial image represented in black, to a partial image with a gradation level value of 255, i.e., a partial image represented in white. A gradation image is composed of N kinds of partial images.
As will be described later, the pattern image may be an image in which N partial images with different gradation level values are regularly arranged, and the specific image configuration is shown in FIGS. Not limited to configuration.

The inspection signal generator 102 is realized by software, for example. In this case, the inspection signal generator 102 is implemented by executing a program including one or more instructions stored in a memory or the like by a processor provided in the image signal output device 100 .
Note that the inspection signal generation unit 102 may generate the above-described image signal by arbitrary processing. For example, the inspection signal generation unit 102 may decode a pre-generated pattern image file compressed in a predetermined format and output an image signal, or may generate an image signal for each pixel according to a predetermined algorithm for generating a pattern image. The image signal may be generated by calculating the pixel values of . Alternatively, the inspection signal generation unit 102 may generate an image signal corresponding to the pattern image by analyzing an image of a pre-printed pattern image captured by a camera.

The image signal output unit 103 is an output circuit that outputs the image signal generated by the non-inspection signal generation unit 101 and the image signal generated by the inspection signal generation unit 102 to the image display device 200 .

The conversion rule setting unit 104 sets the conversion rule of the gradation level value in the conversion unit 202 . Conversion rule setting unit 104 sets a conversion rule for performing predetermined gamma correction in conversion unit 202 during normal operation of image display system 10 . On the other hand, when inspecting the non-linearity of the input/output characteristics in the signal transmission path, the conversion rule setting unit 104 sets the conversion rule for inspection in the conversion unit 202 . Details of the conversion rule for inspection will be described later.

The conversion rule setting unit 104 is realized by software, for example. In this case, the conversion rule setting unit 104 is implemented by the processor of the image signal output device 100 executing a program containing one or more instructions stored in a memory or the like. Note that the conversion rule setting unit 104 may be realized by another configuration. For example, it may be a circuit that outputs a set value of a conversion rule generated in advance and stored in a memory, that is, a set value of an output value for each input value in the conversion unit 202, or it may generate a set value of a conversion rule. It may also be a logic circuit designed as such, ie a digital signal generator. Although the conversion rule setting unit 104 is provided in the image signal output device 100 in the example shown in FIG. 1, it may be provided in the image display device 200 . This also applies to other embodiments described later.

In FIG. 1, the non-inspection signal generation unit 101 and the inspection signal generation unit 102 are shown separately, but the image signal output device 100 has one component having these two functions. may
The image signal generated by the non-inspection signal generation unit 101 and the image signal generated by the inspection signal generation unit 102 are input to the conversion unit 202 of the image display device 200 through a common signal transmission path. . This signal transmission path includes, in addition to the image signal output unit 103 of the image signal output device 100 and the image signal reception unit 201 of the image display device 200, for example, a video card (not shown) of the image signal output device 100, the image signal A video cable (not shown) connecting the output device 100 and the image display device 200 is included. Note that the signal transmission path is not limited to these, and may include any element that performs predetermined processing on the image signal.

The image display device 200 has an image signal reception section 201 , a conversion section 202 and a display section 203 .
The image signal reception unit 201 is a reception circuit that receives image signals output from the image signal output device 100 . The image signal received by the image signal receiving unit 201 is input to the conversion unit 202 . The image signal received by the image signal receiving unit 201 may be input to the conversion unit 202 through predetermined signal processing. That is, other elements (not shown) may exist on the signal transmission path from the image signal receiving unit 201 to the converting unit 202 .
The display unit 203 displays using the image signal converted by the conversion unit 202 .

The conversion unit 202 converts the gradation level value included in the image signal received by the image signal reception unit 201 according to a predetermined conversion rule. In particular, when inspecting the presence or absence of non-linearity of the input/output characteristics in the signal transmission path, the conversion unit 202 performs conversion according to the conversion rule for inspection.

In this embodiment, during inspection, conversion unit 202 converts some of the gradation level values included in the image signal received by image signal reception unit 201 . That is, the conversion unit 202 converts the gradation level values of some of the partial images with various gradation level values included in the pattern image. Specifically, the conversion unit 202 converts the gradation level values corresponding to the terms of the predetermined arithmetic progression according to the conversion rule for inspection. For example, if the predetermined arithmetic progression is an arithmetic progression representing even numbers, the gradation level values corresponding to the terms of the predetermined arithmetic progression are even-numbered gradation level values. Further, for example, when the predetermined arithmetic progression is an arithmetic progression representing odd numbers, the gradation level values corresponding to the terms of the predetermined arithmetic progression are the odd gradation level values. Note that the predetermined arithmetic progression may be another arithmetic progression.

The conversion unit 202 is, for example, an LUT implemented using a memory. In this case, the conversion unit 202 outputs the converted gradation level value held in advance at the address corresponding to the input gradation level value. In this way, conversion section 202 is implemented by, for example, a table-type signal calculator, but may be implemented by other configurations. For example, it may be a logic circuit designed to convert values according to a conversion rule, that is, a digital signal converter. The conversion unit 202 is implemented by, for example, a hardware circuit as described above, but may be implemented by software. That is, the conversion unit 202 may be implemented by a processor included in the image signal output device 100 executing a program containing one or more instructions stored in a memory or the like.

FIG. 4 is a table showing an example of conversion rules for inspection. The conversion rule according to the example shown in FIG. 4 is a conversion rule that changes even-numbered gradation level values to zero. Therefore, in this case, the conversion unit 202 outputs 0 when the gradation level value input to the conversion unit 202 is an even number, and outputs 0 when the gradation level value input to the conversion unit 202 is an odd number. output the tonal level value. As a result, of the partial images included in the pattern image, partial images having even-numbered gradation level values at the time of input to the conversion unit 202 are converted into partial images having a gradation level value of 0. It will happen.

FIG. 5 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 2 when there is no nonlinearity in the signal transmission path. FIG. 6 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. When there is no non-linearity in the signal transmission path, as shown in FIG. 6, a group of partial images with a gradation level value of 0 arranged in the vertical direction and a group of partial images with the original gradation level value arranged in the vertical direction. The groups form a complete striped pattern.

Here, when the linearity of the input/output characteristics of the gradation level cannot be ensured in the signal transmission path up to the conversion unit 202, the gradation level of the pattern image is compared with the time when the test signal generation unit 102 generates the pattern image. A change occurs in the value. For example, if the default brightness or contrast has been changed in the video card settings, even if the software (inspection signal generation unit 102) draws a partial image with a gradation level value of 50, the video card Because the output is changed by a driver or the like, the partial image is converted to a partial image with a different gradation level value such as 49 or 51.

FIG. 7 schematically shows the conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 2 in the case where the gradation level value changes due to nonlinearity in the signal transmission path. It is a diagram. FIG. 8 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. In the example shown in FIG. 7, the following changes in gradation level values occur due to nonlinearity in the signal transmission path. That is, in the original gradation level value range of 21 to 92, the gradation level value increases by 1, and in the original gradation level value range of 93 to 164, the gradation level value increases. In the range of the original gradation level values of 165 to 236, there is a deviation of increasing the gradation level value by 2. In the range of the original gradation level value of 237 There is a shift in which the tone level value increases by 4. As shown in FIG. 7, when the signal transmission path includes nonlinearity, the positions of the partial images whose gradation level values are set to 0 by the conversion of the conversion unit 202 on the image plane become irregular.

As a result, an irregular pattern is formed as shown in FIG. That is, when the gradation level value changes due to non-linearity in the signal transmission path, the pattern shown in FIG. 6 is broken. A slight change in the gradation level value is expressed as a pattern change, so it is easy to visually perceive. 6 is displayed on the display unit 203 or a pattern other than the pattern shown in FIG. It is possible to easily determine the presence or absence of non-linearity in .

Although the image display system 10 has been specifically described above, the above specific description is merely an example. For example, as described above, the pattern image may be an image in which N partial images with different gradation level values are regularly arranged. Therefore, the arrangement of each gradation level value in the pattern image is not limited to the examples shown in FIGS. In the example shown in FIGS. 2 and 3, the partial images are arranged by a predetermined number from the left end to the right end in the order of the gradation level values. Partial images may be arranged in order.

Further, for example, the partial images from the lower limit inspection gradation level value to the upper limit inspection gradation level value may be arranged in the order of gradation levels according to the rule shown in FIG. That is, in the example shown in FIG. 9, a predetermined number of partial images (specifically, 16 partial images each) are vertically arranged from one end (specifically, the upper end) to the other end (specifically, the lower end). ) arranging sub-images is repeated vertically. In the example shown in FIG. 9, the partial images are arranged from the upper end to the lower end, but the partial images may be arranged from the lower end to the upper end.

FIG. 10 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 9 when nonlinearity does not exist in the signal transmission path. FIG. 11 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. When there is no non-linearity in the signal transmission path, as shown in FIG. 11, a group of partial images with a gradation level value of 0 arranged horizontally and a group of partial images with the original gradation level value arranged in a horizontal direction. The groups form a complete striped pattern.

FIG. 12 schematically shows the conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 9 in the case where the gradation level value changes due to nonlinearity in the signal transmission path. It is a diagram. Furthermore, FIG. 13 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. In the examples shown in FIGS. 12 and 13, due to the non-linearity in the signal transmission path, the gradation level values change similarly to the example shown in FIG.

As shown in FIG. 13, when the signal transmission path includes nonlinearity, the positions of the partial images whose gradation level values are set to 0 by the conversion of the conversion unit 202 on the image plane become irregular. As a result, the pattern shown in FIG. 11 is destroyed and an irregular pattern as shown in FIG. 13 is formed.

Further, for example, the partial images from the lower limit test gradation level value to the upper limit test gradation level value may be arranged in the order of gradation level according to the rule shown in FIG. That is, in the example shown in FIG. 14, the arrangement of the partial images in alternating horizontal directions is repeated in the vertical direction. In the example of FIG. 14, the partial image with the gradation level value of 0 is arranged at the upper left corner, and the partial images are arranged in order of the gradation level value. A partial image with a value of 0 may be arranged, and each partial image may be arranged in order of the gradation level value. Also, the arrangement of sub-images in alternating vertical orientations may be repeated in the horizontal direction.

FIG. 15 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 14 when there is no nonlinearity in the signal transmission path. FIG. 16 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. If there is no non-linearity in the signal transmission path, as shown in FIG. 16, a partial image group with a gradation level value of 0 and a partial image group with the original gradation level value form a complete checkerboard pattern. be done. In this way, when the number of partial images arranged in the direction in which the partial images are continuously arranged (for example, the horizontal direction) is an even number, a checkerboard pattern can be formed by the method described above. If the number of partial images to be arranged in the direction in which the partial images are continuously arranged is an odd number, the arrangement of the odd number of partial images from one end to the other in the horizontal direction is repeated in the vertical direction. Thus, a checkered pattern can be formed.

FIG. 17 schematically shows the conversion result when the conversion rule shown in FIG. 4 is applied to the pattern image shown in FIG. 14 in the case where the gradation level value changes due to nonlinearity in the signal transmission path. It is a diagram. Furthermore, FIG. 18 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. In the examples shown in FIGS. 17 and 18, due to the non-linearity in the signal transmission path, the gradation level values change similarly to the example shown in FIG.

As shown in FIG. 18, when the signal transmission path includes non-linearity, the positions of the partial images whose gradation level values are set to 0 by the conversion of the conversion unit 202 become irregular on the image plane. As a result, the pattern shown in FIG. 16 is destroyed and an irregular pattern as shown in FIG. 18 is formed.

In the above description, striped patterns and checkered patterns are given as examples of regular patterns, but regular patterns are not limited to these. For example, as shown in FIGS. 19 to 23, there are two regions: a partial image group region whose gradation level value is set to a predetermined value by conversion by the conversion unit 202 and a partial image group region having the original gradation level value. It may also be a geometric pattern formed by regions. In FIGS. 19 to 23, the hatched area is the area of the partial image group whose gradation level value is set to 0, and the unhatched area is the partial image with the original gradation level value. It is the domain of the group. When the signal transmission path is linear, the partial image group whose gradation level value is set to 0 by the conversion unit 202 is arranged in the hatched area, and the other partial image group is not hatched. These patterns can be obtained by using pattern images arranged in regions.

Also, the conversion rule may be any conversion rule that gives a predetermined pattern (for example, a geometric pattern) to the pattern image when there is no non-linearity in the signal transmission path. Not limited.
For example, in the above-described specific example, the conversion rule is to change even-numbered gradation level values to 0. may be Also, the gradation level value set by the change does not have to be the minimum value of the consecutive N stages of gradation levels. The gradation level value set by the change may be the maximum value (specifically, 255, for example) of consecutive N gradation levels, or any predetermined value between the minimum value and the maximum value.

In this way, the conversion rule is, for example, a rule for uniformly converting gradation level values to be converted into predetermined gradation level values. However, the conversion rule is not limited to a rule for uniformly converting the gradation level value to be converted into a predetermined gradation level value.

For example, the conversion rule may be a rule for performing conversion to shift the input gradation level value by a predetermined level value. That is, the conversion rule may be a rule for adding or subtracting a predetermined level value to or from an input gradation level value. Note that the calculation result wraps around so that the gradation level values after conversion do not deviate from the range of gradation level values that can be displayed by the image display device 200 .

FIG. 24 is a table showing an example of a conversion rule for shifting a gradation level value by a predetermined level value. The conversion rule according to the example shown in FIG. 24 is a conversion rule for changing to add 128 to even-numbered gradation level values. However, if the value after addition exceeds 255, 256 is subtracted from the addition result. That is, a wraparound operation is performed. In this case, if the gradation level value input to the conversion unit 202 is an even number, the conversion unit 202 adds 128 to the input value and outputs the gradation level value obtained by performing the wraparound operation, If the gradation level value input to the conversion unit 202 is an odd number, the input gradation level value is output.

FIG. 25 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 24 is applied to the pattern image shown in FIG. 2 when there is no nonlinearity in the signal transmission path. FIG. 26 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. If there is no nonlinearity in the signal transmission path, a geometric pattern such as that shown in FIG. 26 is formed. Even in such an example, the person in charge of inspection only confirms whether the pattern shown in FIG. , it is possible to easily determine the presence or absence of nonlinearity in the signal transmission path.

In the example shown in FIG. 24, a conversion rule for adding a predetermined value to even-numbered gradation level values is shown, but a conversion rule for subtracting a predetermined value from even-numbered gradation level values may be used. Also, a conversion rule that adds a predetermined value to odd-numbered gradation level values or a conversion rule that subtracts a predetermined value from odd-numbered gradation level values may be used. Furthermore, a conversion rule may be used that adds or subtracts a predetermined value to or from a gradation level value corresponding to a term of a predetermined arithmetic progression other than even and odd numbers.

Also, a conversion rule as shown in FIG. 27 may be used. The conversion rule shown in FIG. 27 uniformly converts gradation level values to be converted that are less than a predetermined threshold to a predetermined first gradation level value, and converts gradation level values that are equal to or greater than this threshold. , is a rule for uniform conversion to a predetermined second gradation level value. Specifically, in the conversion rule shown in FIG. 27, the gradation level values to be converted are even-numbered gradation level values, the predetermined threshold value is 128, and the predetermined first gradation level value is 255 and the predetermined second tone level value is zero. Note that these are only examples, and the gradation level value to be converted may be a gradation level value corresponding to a term of a predetermined arithmetic progression such as an odd number. Also, other values can be adopted for the threshold value, the first gradation level value, and the second gradation level value.

FIG. 28 is a schematic diagram showing a conversion result when the conversion rule shown in FIG. 27 is applied to the pattern image shown in FIG. 2 when there is no nonlinearity in the signal transmission path. Also, FIG. 29 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. If there is no non-linearity in the signal transmission path, a geometric pattern such as that shown in FIG. 29 will be formed. In such an example as well, the person in charge of inspection only confirms whether the pattern shown in FIG. , it is possible to easily determine the presence or absence of nonlinearity in the signal transmission path.

<Embodiment 2>
In the first embodiment, during inspection, conversion unit 202 converts some of the gradation level values included in the image signal received by image signal reception unit 201 . In contrast, in the present embodiment, conversion section 202 converts all gradation level values included in the image signal received by image signal reception section 201 .

Specifically, the conversion unit 202 according to the present embodiment selects the gradation level value to be converted according to which term of the arithmetic progression among the M types of different arithmetic progressions. Convert according to the conversion rules provided. Here, each of the M kinds of different arithmetic progressions is an arithmetic progression with M tolerances. That is, each gradation level value from the lower limit inspection gradation level value to the upper limit inspection gradation level value corresponds to one of the terms of the M kinds of arithmetic progressions. Note that M is a predetermined integer of 2 or more. The conversion unit 202 performs conversion using one of M different predetermined conversion rules according to which term of the arithmetic progression the gradation level value to be converted corresponds to. That is, the conversion rule candidates to be selected are M types of different predetermined conversion rules.

Hereinafter, the value of M is assumed to be 2 for ease of understanding. That is, the conversion unit 202 uses one of the two types of conversion rules according to which of the two types of different arithmetic progressions the gradation level value to be converted corresponds to. to do the conversion. These arithmetic progressions are all arithmetic progressions with a tolerance of two. That is, the two different arithmetic progressions are an arithmetic progression representing even numbers and an arithmetic progression representing odd numbers.

30 is a table showing an example of conversion rules according to the second embodiment; FIG. The table shown in FIG. 30 includes two types of conversion rules, a first conversion rule and a second conversion rule.
Specifically, the first conversion rule is a conversion rule applied when the gradation level value to be converted, that is, the gradation level value input to the conversion unit 202 is an even number. This conversion rule is a conversion rule that changes the gradation level value to zero. In other words, the first conversion rule is a conversion rule selected corresponding to an arithmetic progression representing even numbers, and uniformly converts the gradation level values to be converted into predetermined first gradation level values. It is a rule to
The second conversion rule is a conversion rule applied when the gradation level value to be converted, that is, the gradation level value input to the conversion unit 202 is an odd number. This conversion rule is a conversion rule to change the gradation level value to 255. In other words, the second conversion rule is a conversion rule selected corresponding to an arithmetic sequence representing odd numbers, and uniformly converts the gradation level values to be converted into predetermined second gradation level values. It is a rule to
Note that one of the first gradation level value and the second gradation level value is, for example, the minimum value of the continuous N-stage gradation levels, and the other is the maximum value of the continuous N-stage gradation levels. value.
Thus, in the example shown in FIG. 30, the conversion unit 202 uses a conversion rule to change even-numbered gradation level values to 0 and a conversion rule to change odd-numbered gradation level values to 255. converts all the gradation level values included in the image signal received by the image signal receiving unit 201 .

FIG. 31 is a schematic diagram showing a pattern image when the conversion rule shown in FIG. 30 is applied to the pattern image shown in FIG. 2 when there is no nonlinearity in the signal transmission path. If there is no non-linearity in the signal transmission path, as shown in FIG. 31, a group of partial images with a gradation level value of 0 arranged vertically and a group of partial images with a gradation level value of 255 arranged in the vertical direction. The groups form a complete striped pattern.

In the present embodiment, as in the first embodiment, the pattern shown in FIG. 31 collapses when the gradation level value changes due to nonlinearity in the signal transmission path. In this way, a slight change in the gradation level value is represented as a change in the pattern, making it easy to visually perceive. 31 is displayed on the display unit 203 or a pattern other than the pattern shown in FIG. It is possible to easily determine the presence or absence of non-linearity in .

Also in the present embodiment, the pattern image may be an image in which N partial images with different gradation level values are regularly arranged. For this reason, the arrangement of each gradation level value in the pattern image can have various variations as in the first embodiment.

Also in the present embodiment, the conversion rule may be any conversion rule that gives a predetermined pattern (for example, a geometric pattern) to the pattern image when there is no nonlinearity in the signal transmission path. , is not limited to the above specific examples. For example, if the first transformation rule is to change even tone level values to 255 and the second transformation rule is to change odd tone level values to 0, good too. Also, the gradation level values set by the change need not be the minimum and maximum values of the consecutive N gradation levels. That is, the gradation level value set by the change may be any predetermined value between the minimum value and the maximum value. In this way, each conversion rule is, for example, a rule for uniformly converting gradation level values to be converted into predetermined gradation level values. In other words, the conversion unit 202 converts all gradation level values into one of M types of gradation level values. However, conversion rules are not limited to such conversion rules.

For example, also in the present embodiment, the conversion rule may be a rule for performing conversion by shifting the input gradation level value by a predetermined level value. That is, the conversion rule may be a rule for adding or subtracting a predetermined level value to or from an input gradation level value.

FIG. 32 is a table showing an example of a conversion rule for shifting a gradation level value by a predetermined level value. The conversion rule according to the example shown in FIG. 32 is a conversion rule of adding −64 to even-numbered gradation level values and adding 64 to odd-numbered gradation level values. However, if the value after addition is less than 0, 256 is added to the addition result, and if the value of the addition sign exceeds 255, 256 is subtracted from the addition result. That is, a wraparound operation is performed.
In this case, if the gradation level value input to the conversion unit 202 is an even number, the conversion unit 202 adds -64 to the input value and outputs the gradation level value obtained by performing the wraparound operation. . If the gradation level value input to the conversion unit 202 is an odd number, the conversion unit 202 adds 64 to the input value and outputs the gradation level value obtained by performing the wraparound operation. In the example shown in FIG. 32, the absolute value of the value added to the even-numbered gradation level value and the absolute value of the value added to the odd-numbered gradation level value are the same. good.

FIG. 33 is a schematic diagram showing a pattern image when the conversion rule shown in FIG. 32 is applied to the pattern image shown in FIG. 2 when nonlinearity does not exist in the signal transmission path. FIG. 34 is a schematic diagram showing a pattern image formed by arranging the partial images shown in FIG. If there is no non-linearity in the signal transmission path, a geometric pattern such as that shown in FIG. 34 is formed. In such an example as well, the person in charge of inspection only confirms whether the pattern shown in FIG. , it is possible to easily determine the presence or absence of nonlinearity in the signal transmission path.

<Embodiment 3>
Next, Embodiment 3 will be described. In the above-described embodiment, one pattern image is used in which a plurality of partial images with continuously different gradation level values are arranged on the image plane. On the other hand, in the present embodiment, a plurality of images with continuously different gradation level values are used. That is, in the above-described embodiment, the presence or absence of non-linearity is determined by displaying one pattern image on the display unit 203, but in the present embodiment, a plurality of images are sequentially displayed on the display unit 203. Judgment is made by displaying

Details of the third embodiment will be described below. However, descriptions of the same configurations and processing contents as those of the above-described embodiment will be omitted as appropriate.

FIG. 35 is a block diagram showing an example of the configuration of the image display system 30 according to the third embodiment. As shown in FIG. 35 , the image display system 30 has an image signal output device 150 , an image display device 200 and a display brightness measurement device 300 .

Also in this embodiment, the image signal output device 150 and the image display device 200 are communicably connected by wire or wirelessly. Also, the display luminance measuring device 300 and the image signal output device 150 are communicably connected by wire or wirelessly.

The image signal output device 150 differs from the image signal output device 100 according to the above-described embodiment in that the inspection signal generation unit 102 is replaced with the inspection signal generation unit 151 and a display luminance determination unit 152 is added. different.
The display luminance determination unit 152 is realized by software, for example. In this case, the display brightness determination unit 152 is realized by executing a program including one or more instructions stored in a memory or the like by the processor provided in the image signal output device 150 . Note that the display luminance determination unit 152 may be provided in the image display device 200 or another device instead of the image signal output device 150 .

A display luminance measuring device 300 is a sensor that measures the luminance of an image displayed on the display unit 203 . The display brightness measuring device 300 digitizes the brightness of the image displayed by the display unit 203 and outputs the brightness to the image signal output device 150 . The measurement result of the display brightness measuring device 300 is input to the display brightness determination section 152 of the image signal output device 150 . The display luminance measuring device 300 measures the luminance of at least an area of the screen of the display unit 203 where the image represented by the image signal generated by the test signal generation unit 151 is displayed. The display luminance measuring device 300 is fixedly installed, for example, at the edge of the screen. However, the display brightness measuring device 300 does not necessarily have to be fixedly installed in the image display device 200 . That is, for example, a person in charge of inspection may measure the brightness of an image represented by the image signal generated by the inspection signal generator 151 by holding the display brightness measuring device 300 by hand.

The inspection signal generation unit 151, like the inspection signal generation unit 102, also generates an image to be displayed on the image display device 200 at the time of inspection, that is, an image for inspecting the nonlinearity of the input/output characteristics in the signal transmission path. Generate an image signal. In the following, descriptions of the inspection signal generation unit 151 that overlap with those of the inspection signal generation unit 102 will be omitted as appropriate.

The inspection signal generation unit 151 sequentially generates image signals of N images (N is an integer equal to or greater than 2) having different gradation level values. Here, the gradation level of the n-th (n is an integer from 1 to N) generated image among the N images is the n-th gradation level of the N successive gradation levels. In other words, the grayscale level of the image for the nth display is the nth grayscale level of N successive grayscale levels. The continuous N stages of gradation levels are as described in the description of the first embodiment.

For example, the inspection signal generator 151 sequentially generates image signals of N images so that the gradation level values are in ascending order. Specifically, for example, the inspection signal generation unit 151 first generates an image signal of a uniform image with a gradation level value of 0, and then generates an image signal of a uniform image with a gradation level value of 1. Generate an image signal. The inspection signal generator 151 similarly generates image signals thereafter. Note that the inspection signal generation unit 151 may sequentially generate image signals of N images so that the gradation level values are in descending order. Among the N images sequentially output from the image signal output device 150 at the time of inspection, the gradation level of the n-th image output is the n-th gradation level of the consecutive N gradation levels.

The inspection signal generation unit 151 outputs the generated image signal to the image signal output unit 103 . The inspection signal generation unit 151 may switch the image signal to be output to the image signal output unit 103 every predetermined display time, or may change the image signal to be output to the image signal output unit 103 based on an instruction from the user. can be switched. That is, the output of the image of the next gradation level value may be performed automatically, or may be performed based on the instruction from the user. The image signal generated by the inspection signal generation unit 151 is output to the image display device 200 by the image signal output unit 103 . The image signal output from the image signal output device 150 is received by the image signal receiving section 201 of the image display device 200 and then input to the conversion section 202 .

During inspection, the conversion unit 202 converts the gradation level values included in the image signal received by the image signal reception unit 201 according to a predetermined conversion rule, as in the first or second embodiment. Note that, in the present embodiment, the conversion unit 202 converts some of the gradation level values included in the image signal received by the image signal reception unit 201, as in the first embodiment. Alternatively, as in the second embodiment, all gradation level values may be converted. Also, in the present embodiment, any one of the conversion methods described in the descriptions of the first and second embodiments may be used. Therefore, for example, the conversion unit 202 may convert the gradation level values corresponding to the terms of a predetermined arithmetic progression according to the conversion rule associated with the arithmetic progression. A plurality of predetermined arithmetic progressions may be used. That is, different conversion rules may be associated with each arithmetic progression. Further, the conversion rule may be a rule that uniformly converts the gradation level value to be converted into a predetermined gradation level value, or a conversion that shifts the gradation level value by a predetermined level value. It can be a rule.

In Embodiment 1 or Embodiment 2, when nonlinearity exists in the signal transmission path, the regular two-dimensional pattern that appears when there is no nonlinearity in the signal transmission path collapses. On the other hand, in the present embodiment, when nonlinearity exists in the signal transmission path, the regular temporal change in luminance that appears when there is no nonlinearity in the signal transmission path collapses. That is, a slight change in the gradation level value in the signal transmission path is expressed as a disturbance in the regular temporal change of luminance, so that it is easy to visually perceive. In the present embodiment, as will be described later, the display brightness measuring device 300 and the display brightness determination unit 152 perform determination processing by equipment. Determination by is also possible. In that case, the display brightness measuring device 300 and the display brightness determination section 152 can be omitted.

Specifically, in this embodiment, during inspection, conversion unit 202 uses a conversion rule for converting a sequence in which gradation level values change continuously into a sequence in which gradation level values repeatedly increase and decrease. As such a conversion rule, for example, the conversion rule shown in FIG. 4 can be used. It is also possible to use

Note that, for example, when a conversion rule is used to change odd-numbered gradation level values to 0, if an image with a gradation level value of 0 and an image with a gradation level value of 1 are sequentially input to the conversion unit 202, , images with a gradation level value of 0 are displayed continuously. That is, strictly speaking, this conversion rule is not a conversion rule for conversion into a numerical sequence in which gradation level values repeatedly increase and decrease. However, in the present disclosure, a numerical sequence in which gradation level values do not repeatedly increase and decrease in a part of the numerical sequence after conversion is also referred to as a numerical sequence in which gradation level values repeatedly increase and decrease. In view of the strictness described above, the conversion unit 202 converts a numerical sequence in which the gradation level values continuously change into a numerical sequence in which the gradation level values repeatedly increase and decrease over successive terms in a predetermined range. It can also be said that a conversion rule that converts is used.

The image signal output from the conversion unit 202 is displayed on the display unit 203 . Then, the luminance of the grayscale image displayed on the display unit 203 is measured by the display luminance measuring device 300 and the luminance is transmitted to the display luminance determination unit 152 .

The display luminance determination unit 152 determines whether or not the luminance measured by the display luminance measuring device 300 repeats increases and decreases. That is, it is determined whether or not the luminance changes so as to repeat increase and decrease according to the image signals sequentially output from the image signal output device 150 . When the measured luminance repeatedly increases and decreases, that is, when there is a regular change in luminance over time, the gradation level values of the continuous images sequentially output from the image signal output device 150 are not accompanied by fluctuations in values. is input to the conversion unit 202 as it is. On the other hand, if the measured luminance does not repeat increases and decreases, that is, if there is disturbance in the regular temporal change of luminance, the gradation of the continuous image sequentially output from the image signal output device 150 It means that the level value is input to the conversion unit 202 with a change in value.

The display luminance determination unit 152 determines the series of measured luminances of a series of continuous images from the lower (upper limit) test gradation level value to the upper (lower limit) test gradation level value output from the image signal output device 150. If the increase/decrease is repeated, it is determined that the signal transmission path does not have nonlinearity.
On the other hand, the display luminance determination unit 152 performs a series of measurements on a series of continuous images from the lower (upper limit) test gradation level value to the upper (lower limit) test gradation level value output from the image signal output device 150. If the received luminance does not repeatedly increase and decrease, it is determined that the signal transmission path has nonlinearity.
As described above, strictly speaking, a conversion rule that cannot be said to be a conversion rule for converting a numerical sequence in which the gradation level values continuously change into a numerical sequence in which the gradation level values repeatedly increase and decrease may be used. In this case, the display luminance determination unit 152 selects a predetermined one of a series of continuous images from the lower (upper limit) test gradation level value to the upper (lower limit) test gradation level value output from the image signal output device 150. It is only necessary to determine whether or not the measured luminance repeats increases and decreases for the series.

FIG. 36 is a flow chart showing an example of the operation of the image display system 30 according to the third embodiment. The flow of operation of the image display system 30 during inspection will be described below with reference to FIG.

In step S<b>100 , the conversion rule setting unit 104 sets conversion rules for inspection in the conversion unit 202 . The conversion rule used here is a conversion rule for converting a numerical sequence in which the gradation level values continuously change into a numerical sequence in which the gradation level values repeatedly increase and decrease.

Next, in step S101, the test signal generator 151 sets the value of the variable L to an initial value. Here, the variable L is a variable that designates the gradation level value of the image to be displayed on the image display device 200 during inspection. For example, the inspection signal generator 151 sets the variable L to the lower limit inspection gradation level value (eg, 0) as an initial value.

Next, in step S102, the inspection signal generator 151 generates an image signal of the image with the gradation level value specified by the variable L. FIG. The image signal output unit 103 then outputs the generated image signal to the image display device 200 . Then, this image signal is received by the image signal receiving unit 201 .

Next, in step S103, the conversion unit 202 performs conversion processing of the gradation level value of the image signal received by the image signal reception unit 201 according to the conversion rule set in step S100.

Next, in step S104, the display unit 203 displays an image based on the image signal converted in step S103.

Next, in step S105, the display luminance measuring device 300 measures the luminance of the image displayed on the display unit 203 in step S104. Then, the measurement result is transmitted to the display brightness determination section 152 .

Next, in step S106, the display luminance determination unit 152 determines whether or not a series of measured luminance values alternately repeat increases and decreases in time series. That is, the display luminance determination unit 152 determines whether increases and decreases in luminance alternately occur in time series. In other words, the display luminance determination unit 152 determines whether or not the pattern of the series of time-series data of the measured luminance values conforms to a data pattern that alternately repeats increases and decreases.

Note that when the value of the variable L is the initial value, there is only one brightness data obtained as a measurement result, so the above-described processing in this determination step is omitted, and the processing proceeds to step S107. In addition, the display luminance determination unit 152 determines that the value of the variable L is not the initial value and that the pattern of the time-series data of the series of measured luminance values follows the data pattern that alternately repeats increases and decreases. Also when it is done, the process moves to step S107. If the value of the variable L is not the initial value and the pattern of the time-series data of the series of measured luminance values does not conform to the data pattern that alternately repeats increases and decreases, the process proceeds to step S109. do.

In step S107, the inspection signal generator 151 determines whether or not the value of the variable L satisfies a predetermined termination condition. For example, the inspection signal generation unit 151 determines whether the value of the variable L is the upper limit inspection gradation level value (for example, 255). If the value of variable L does not satisfy the termination condition, the process proceeds to step S108. On the other hand, if the value of variable L satisfies the termination condition, the process proceeds to step S110.

In step S108, the inspection signal generator 151 increases the current value of the variable L by one. In the example shown in FIG. 36, the gradation level values are set in ascending order, but the gradation level values may be set in descending order. In this case, the test signal generator 151 decrements the current value of the variable L by one in step S108. After step S108, the process returns to step S102.

In step S109, the display luminance determination unit 152 determines that there is a nonlinear characteristic in the signal transmission path, and terminates the inspection.
On the other hand, in step S110, the display brightness determination unit 152 determines that there is no nonlinear characteristic in the signal transmission path, and terminates the inspection.

The third embodiment has been described above. As described above, in the present embodiment, a series of images output with the gradation level values continuously changed in time series are sequentially output to the display unit 203 via the conversion unit 202 . Then, when there is nonlinearity in the signal transmission path, the regular change over time of the brightness of the image displayed on the display unit 203 is disturbed. Therefore, by detecting this by equipment or by an inspector, it is possible to easily confirm whether there is nonlinearity in the input/output characteristics of the signal transmission path.

It should be noted that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the scope of the invention. For example, in each of the above-described embodiments, the display of numerical values indicating the gradation level values set in the inspection signal generation units 102 and 151 is superimposed on the image to be displayed on the image display device 200 during inspection. good too. In other words, the inspection signal generation unit 102 may superimpose the gradation level value of each partial image forming the pattern image. Moreover, the inspection signal generation unit 151 may superimpose the gradation level value of the image on each of the series of images for inspection. Note that the gradation level value of the superimposed character is a gradation level value with a contrast difference of a predetermined value or more from the background image. By doing so, the gradation level value set in the image signal output device 100 can be confirmed on the display unit 203 . Therefore, it is possible for the person in charge of the inspection to easily grasp which gradation level value is affected by the nonlinear characteristic.

By the way, in general, monitor products for business use such as medical monitors are equipped with a function for adjusting display characteristics and a function for inspecting display characteristics. Specifically, as a function for adjusting the display characteristics, a function for matching the gamma characteristics of the display with the gamma characteristics complying with medical standards is installed. More specifically, an LUT is installed in the monitor itself, and software is provided to give the desired gamma characteristics to this LUT. Then, by operating using software, LUT data for realizing the desired gamma characteristics is generated, and by using the communication function of the software to write this in the LUT built in the monitor body, the desired gamma characteristics can be obtained. It can be adjusted to achieve gamma characteristics. Further, as a function of inspecting the display characteristics, a function of inspecting defects in the display characteristics by displaying a test pattern with the software and visually checking the pattern is installed.

The above-described embodiments may be realized by utilizing the function for adjusting the display characteristics and the function for inspecting the display characteristics, which are provided in advance in the monitor product. Thereby, the introduction cost of the embodiment described above can be suppressed. Specifically, the inspection signal generators 102 and 151 may be realized by utilizing software pre-installed in the monitor as a function of inspecting the display characteristics. Further, the conversion unit 202 may be realized by utilizing a gamma characteristic generation LUT that is pre-installed in the monitor as a function for adjusting display characteristics. Also, the conversion rule setting unit 104 may be realized by utilizing software pre-installed in the monitor as a function for adjusting display characteristics.

The programs described above can be stored and provided to computers using various types of non-transitory computer readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (eg, floppy disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg, magneto-optical discs), Compact Disc Read Only Memory (CD-ROM), CD- R, CD-R/W, semiconductor memory (eg Mask ROM, Programmable ROM (PROM), Erasable PROM (EPROM), Flash ROM, Random Access Memory (RAM)). The program may also be supplied to the computer on various types of transitory computer readable medium. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. Transitory computer-readable media can deliver the program to the computer via wired channels, such as wires and optical fibers, or wireless channels.

10 image display system 30 image display system 100 image signal output device 101 non-inspection signal generation unit 102 inspection signal generation unit 103 image signal output unit 104 conversion rule setting unit 150 image signal output device 151 inspection signal generation unit 152 display luminance Determination unit 200 Image display device 201 Image signal reception unit 202 Conversion unit 203 Display unit 300 Display luminance measurement device

Claims (7)

an image signal receiving unit that receives an image signal of a pattern image in which N (N is an integer equal to or greater than 2) partial images with different gradation level values are regularly arranged;
a conversion unit that converts some of the gradation level values included in the image signal into gradation level values according to a predetermined conversion rule;
a display unit that displays using the image signal converted by the conversion unit;
the gradation level value of the n-th (n is an integer of 1 or more and N or less) partial image among the N partial images is the n-th gradation level value of successive N stages of gradation levels;
The conversion unit converts a gradation level value corresponding to a term of a predetermined arithmetic progression according to the predetermined conversion rule ,
The predetermined arithmetic progression is an arithmetic progression representing even numbers or an arithmetic progression representing odd numbers
Image display device. The image display device according to claim 1 , wherein the conversion rule is a conversion rule for adding a predetermined pattern to the pattern image. 3. The image display device according to claim 1, wherein the conversion rule is a rule for uniformly converting gradation level values into predetermined gradation level values. 4. The image display device according to claim 3 , wherein the predetermined gradation level value is a minimum value or a maximum value of the consecutive N stages of gradation levels. 3. The image display device according to claim 1, wherein the conversion rule is a rule for performing conversion by shifting a gradation level value by a predetermined level value. The conversion rule uniformly converts gradation level values less than a predetermined threshold to a predetermined first gradation level value, and converts gradation level values equal to or greater than the threshold to a predetermined second gradation level value. 3. The image display device according to claim 1 or 2 , wherein the rule uniformly converts to . receiving an image signal of a pattern image in which N (N is an integer equal to or greater than 2) partial images with different gradation level values are regularly arranged;
Converting some of the gradation level values included in the image signal according to a predetermined conversion rule,
display using the converted image signal;
the gradation level value of the n-th (n is an integer of 1 or more and N or less) partial image among the N partial images is the n-th gradation level value of successive N stages of gradation levels;
In the conversion, the gradation level values corresponding to the terms of the predetermined arithmetic progression are converted according to the predetermined conversion rule ;
The predetermined arithmetic progression is an arithmetic progression representing even numbers or an arithmetic progression representing odd numbers
Inspection methods.

Images