JP2006340225A - Video determination apparatus, display device and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video determination apparatus which extremely easily and fast determines whether a correction curve (gradation correction table) is abnormal or not and performs correction processing of the correction curve if the correction curve is abnormal, and a display device in which the video determination apparatus is mounted, or the like. <P>SOLUTION: A storage section 17 is comprised of a first storage part 17a for storing a gradation correction table (standard gradation correction table) created in advance for the display device and a second storage part 17b for storing one or more gradation correction tables (user gradation correction tables) originally created by a user or the like. A data processing section 18 comprises a difference processing part 18a for performing difference processing on the gradation correction table set by the user, a determination processing part 18b for determining whether the gradation correction table is abnormal or not based on differential values at points of the gradation correction table, and a correction processing part 18c for performing correction processing on the gradation correction table if it is determined that the gradation correction table is abnormal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention determines whether or not a correction curve or gradation correction table for correcting the signal level of a video signal is abnormal, and if it is determined to be abnormal, a correction curve (tone correction table) is determined. And a computer program for realizing a function as a video determination device by a computer.

  Display devices (including projectors) such as liquid crystal displays, CRT displays, plasma displays, and field emission displays (FEDs) have different optical characteristics for each device itself, and are corrected to manage and unify the color characteristics. A curve (FIG. 9A) is set, and the display color is set by adjusting the emission intensity of each color based on the correction curve. For example, a gradation correction table (FIG. 9B) for changing the signal level of the video signal corresponding to the correction curve is stored in the memory, and the input video signal is based on the gradation correction table. Change the signal level and output.

The gradation correction table is a table for freely correcting video signals, and is a comparison table of input levels and output levels for correcting digitized gradation data to an arbitrary gradation. The video signal is corrected using the gradation correction table, and detailed correction such as “increasing the brightness of a dark part” is possible.
JP 2002-116750 A

  Incidentally, as shown in FIG. 10, the gradation correction table has an output level 910 corresponding to the input level 209, an output level 900 corresponding to the input level 210, and an output level 918 corresponding to the input level 211. Even in the abnormal state where the output level is reversed at the input level 210, the user transmits the generated gradation correction table data to the display device without noticing that the user is abnormal. The user sees the video displayed on the display device, grasps that there is a problem with the gradation correction table for the first time, and recreates the gradation correction table. For example, when gradation display such as a step ladder is performed based on the gradation correction table as shown in FIG. 10, as shown in FIG. 11, an image in which light and dark are reversed at a position corresponding to an input level of 210. There was a problem that was displayed. Therefore, it is necessary for the user to manually correct, and the data of the gradation correction table has to be retransmitted each time correction is made, and there is a problem that it takes time and effort. As described above, in the conventional technique, there is a possibility that the gradation correction table is repeatedly created and modified, and an abnormality in the gradation correction table is automatically detected, and further, the gradation correction table can be automatically corrected. Technology was desired.

  Further, when the display device can display 256 gradations, the display ability of the display device cannot be sufficiently exhibited by the correction curve for 64 gradations. The gradation is a stage in which the color and brightness change. The more the gradation, the more smoothly the change in color and brightness can be expressed, and the continuous color change in the natural world can be reproduced. In such a case, conventionally, as shown in FIG. 12, 256 gradations are divided into four gradations, 0 level at 64 gradations is changed to 0 to 3 levels at 256 gradations, and 1 at 64 gradations. The level is set to 4 to 7 level at 256 gradations,..., 63 level at 64 gradations is set to 252 to 255 level at 256 gradations. Therefore, for example, when the input level of the video signal is 0 to 3, the light emission intensity becomes the same, and the display capability is not sufficiently exhibited.

  The present invention has been made in view of such circumstances, and an image determination apparatus capable of determining whether or not a correction curve (tone correction table corresponding to the correction curve) is abnormal is extremely simple and at high speed. The purpose is to provide a computer program.

  Another object of the present invention is to provide an image determination apparatus that corrects a correction curve (tone correction table) when a correction curve (tone correction table corresponding to the correction curve) is abnormal.

  Further, the present invention can save a storage capacity for storing a correction curve (a gradation correction table corresponding to the correction curve), can store a plurality (many) of gradation correction tables, and has color reproducibility. An object is to provide an excellent display device.

  A video determination apparatus according to the present invention includes a differential processing unit that performs differential processing on an output level of a correction curve in which an input level and an output level are associated with each other in order to correct the signal level of the video signal, And determining means for determining whether or not the correction curve is abnormal based on positive or negative.

  In the video determination device according to the present invention, the correction curve corresponds to one gradation degree, and the differentiation processing unit performs a differentiation process when the correction curve corresponds to another gradation degree. It is characterized by being.

  The video determination apparatus according to the present invention is characterized by comprising means for correcting the correction curve when the correction curve is determined to be abnormal.

  The video determination apparatus according to the present invention calculates a difference value between output levels corresponding to two input levels in a gradation correction table in which an input level and an output level are associated with each other in order to correct the signal level of the video signal. Difference calculating means, and means for determining whether or not the gradation correction table is abnormal based on the sign of the calculated difference value.

  In the video determination apparatus according to the present invention, the gradation correction table corresponds to one gradation degree, and the difference calculation means calculates a difference value when the gradation correction table corresponds to another gradation degree. It is characterized by being calculated.

  The video determination apparatus according to the present invention is characterized by comprising means for correcting the gradation correction table when the gradation correction table is determined to be abnormal.

  The display device according to the present invention includes a video signal acquisition unit that acquires a video signal, the above-described video determination device, and the video signal acquired by the video signal acquisition unit based on a correction curve corrected by the video determination device. A correction unit that corrects a signal level, and a display unit that displays an image related to a video signal in which the correction unit corrects the signal level are provided.

  The display device according to the present invention includes a video signal acquisition unit that acquires a video signal, the above-described video determination device, and a video acquired by the video signal acquisition unit based on a gradation correction table corrected by the video determination device. A correction unit that corrects the signal level of the signal, and a display unit that displays an image related to the video signal whose signal level is corrected by the correction unit.

  A computer program according to the present invention is a computer program for determining whether a correction curve associated with an input level and an output level is abnormal in order to correct a signal level of a video signal. , Causing the output level of the correction curve to be differentiated at an input level, and causing the computer to determine whether the correction curve is abnormal based on whether the differential value is positive or negative. And

  A computer program according to the present invention is a computer program for determining whether or not a gradation correction table in which an input level and an output level are associated is abnormal in order to correct a signal level of a video signal. And causing the computer to calculate a difference value between the output levels corresponding to the two input levels of the gradation correction table and whether or not the gradation correction table is abnormal based on whether the difference value is positive or negative. And a step of determining the above.

  According to the present invention, the output level of the correction curve in which the input level and the output level of the video signal are associated with each other is subjected to a differentiation process. Thus, it can be seen that when the differential value is positive, the correction curve is rising to the right, and when the differential value is negative, the correction curve is decreasing to the right. In general, when the correction curve is not monotonously increasing (upward to the right) or monotonously decreasing (downward to the right), the reversal of light and dark occurs, resulting in trouble with color reproduction. Therefore, it is possible to determine whether or not the correction curve is abnormal based on the differential value obtained by performing the differentiation process with the correction curve. Therefore, it is possible to quickly determine whether or not the correction curve is abnormal by an extremely simple process of differentiation of the correction curve. Conventionally, even when an image is displayed on a display device, depending on the signal pattern of the video signal, the user may not be able to grasp the abnormality of the correction curve. There is no such a fear from judging abnormality.

  In the present invention, the correction curve corresponds to one gradation degree (for example, 64 gradations), and differentiation processing is performed when the correction curve corresponds to another gradation degree (for example, 256 gradations). Based on the obtained differential value, it is determined whether or not the correction curve corresponds to a higher gradation. For example, when the correction curve has a stepped shape (step function) having 64 gradations, there exists an input level at which the differential value obtained by performing the differential processing becomes zero. Before and after the input level where the differential value is zero, even if the input level of the video signal is different, it is corrected to the same output level. Therefore, it is impossible to make this correction curve correspond to a high gradation level. As described above, it is possible to quickly determine whether or not the correction curve corresponds to another high gradation degree by an extremely simple process of differentiation of the correction curve.

  In the present invention, the correction curve is corrected when it is determined that the correction curve is abnormal. As described above, the abnormality of the correction curve can be automatically detected and the correction curve can be automatically corrected, so that the user need not repeat the creation and correction of the correction curve.

  In the present invention, the difference value between the output levels corresponding to the two input levels of the gradation correction table in which the input level and the output level are associated is calculated. Thereby, it can be determined whether the correction curve corresponding to the gradation correction table is rising to the right or falling to the right. That is, it can be seen that when the difference value is positive, the correction curve is rising to the right, and when the difference value is negative, the correction curve is falling to the right. Therefore, it is possible to determine whether or not the gradation correction table is abnormal based on the calculated difference value. Therefore, it is possible to quickly determine whether or not the gradation correction table is abnormal by an extremely simple process called difference. Conventionally, even when an image is displayed on a display device, depending on the signal pattern of the image signal, the user may not be able to grasp the abnormality of the gradation correction table. Since there is an abnormality in the tone correction table, there is no such concern.

  In the present invention, the gradation correction table corresponds to one gradation degree (for example, 64 gradations), and the difference is obtained when the gradation correction table is associated with another gradation degree (for example, 256 gradations). Processing is performed to determine whether or not the gradation correction table corresponds to a higher gradation degree based on the obtained difference value. Before and after the input level where the difference value is zero, even if the input level of the video signal is different, it is corrected to the same output level. Therefore, it is impossible to make this gradation correction table correspond to a high gradation degree. In this way, it is possible to quickly determine whether or not the gradation correction table is compatible with other high gradation levels by an extremely simple process called a difference between gradation correction tables.

  In the present invention, the gradation correction table is corrected when it is determined that the gradation correction table is abnormal. As described above, the abnormality of the gradation correction table is automatically detected, and further, the correction process of the gradation correction table can be automatically performed. Therefore, the user needs to repeat the creation and correction of the gradation correction table. Disappear.

  In the present invention, differentiation processing is performed on the correction curve, and it is determined whether or not the correction curve is abnormal based on the sign of the obtained differential value, and correction is performed when it is determined that the correction curve is abnormal. Correct the curve. Then, based on the corrected correction curve, the signal level of the acquired video signal is corrected, and the video related to the corrected video signal is displayed on the display unit. As a result, the abnormality of the correction curve can be automatically detected and the correction curve can be corrected automatically, so that the user does not need to repeat the creation and correction of the correction curve, and the display unit A faulty video is never displayed.

  In the present invention, difference processing is performed on the gradation correction table, and it is determined whether or not the gradation correction table is abnormal based on the sign of the obtained difference value. If this happens, the tone correction table is corrected. Then, based on the corrected gradation correction table, the signal level of the acquired video signal is corrected, and the video related to the corrected video signal is displayed on the display unit. As a result, an abnormality in the gradation correction table can be automatically detected and the correction process of the gradation correction table can be automatically performed, so that the user need not repeat the creation and correction of the gradation correction table. At the same time, a defective image is not displayed on the display unit.

  According to the present invention, the output level of the correction curve associated with the input level and the output level is differentiated at the input level, and it is determined whether the correction curve is abnormal based on the obtained differential value. Since the configuration is adopted, it is possible to quickly determine whether or not the correction curve is abnormal by an extremely simple process of differentiation of the correction curve. Conventionally, even when an image is displayed on a display device, depending on the signal pattern of the video signal, the user may not be able to grasp the abnormality of the correction curve. There is no such a fear from judging abnormality. In addition, if the user is notified of the determination result of whether or not the correction curve is abnormal, the user can grasp that the correction curve has a defect without displaying an image on the display device. Thus, it is possible to take measures such as recreating a correction curve.

  According to the present invention, the correction curve corresponds to one gradation, and when the correction curve corresponds to another gradation, the differentiation process is performed, and the correction curve is determined based on the obtained differential value. Therefore, it is possible to quickly determine whether the correction curve corresponds to another gradation level (for example, high gradation level) by a very simple process called differentiation of the correction curve. Can be determined.

  According to the present invention, since the correction curve is corrected when it is determined that the correction curve is abnormal, the correction curve abnormality is automatically detected, and the correction curve correction processing can be automatically performed. This eliminates the need for the user to repeat the creation and correction of the correction curve.

  According to the present invention, the difference value between the output levels corresponding to the two input levels of the gradation correction table in which the input level and the output level are associated is calculated, and the gradation correction table is based on the calculated difference value. Therefore, it is possible to quickly determine whether or not the gradation correction table is abnormal by an extremely simple process called difference. Conventionally, even when an image is displayed on a display device, depending on the signal pattern of the image signal, the user may not be able to grasp the abnormality of the gradation correction table. Since there is an abnormality in the tone correction table, there is no such concern. Further, if the user is notified of the determination result as to whether or not the gradation correction table is abnormal, the user has a problem with the gradation correction table without having to display an image on the display device. It is possible to grasp this fact and take measures such as recreating the gradation correction table.

  According to the present invention, the gradation correction table corresponds to one gradation degree, and when the gradation correction table is associated with another gradation degree, the difference processing is performed and the calculated difference value is used. Since the gradation correction table is configured to determine whether or not the gradation correction table corresponds to another gradation degree, the gradation correction table can be changed to another gradation degree (for example, a higher order) by an extremely simple process called a difference of the gradation correction table. It is possible to quickly determine whether or not it corresponds to the furniture.

  According to the present invention, since the gradation correction table is corrected when it is determined that the gradation correction table is abnormal, the abnormality of the gradation correction table is automatically detected, and further automatically Since the correction process of the tone correction table can be performed, the user does not need to repeat the creation and correction of the gradation correction table.

  According to the present invention, a differentiation process is performed on the correction curve, and it is determined whether or not the correction curve is abnormal based on whether the obtained differential value is positive or negative, and when it is determined that the correction curve is abnormal, the correction curve is determined. , And based on the corrected correction curve, the signal level of the acquired video signal is corrected, and the video related to the corrected video signal is displayed on the display unit. In addition, since the correction curve can be corrected automatically, the user does not need to repeat the creation and correction of the correction curve, and no defective image is displayed on the display unit.

  According to the present invention, difference processing is performed on the gradation correction table, and it is determined whether or not the gradation correction table is abnormal based on whether the obtained difference value is positive or negative. In this case, the gradation correction table is corrected, the signal level of the acquired video signal is corrected based on the corrected gradation correction table, and the video related to the corrected video signal is displayed on the display unit. An abnormality in the tone correction table can be automatically detected and the gradation correction table can be automatically corrected, so that the user does not need to repeat the creation and correction of the gradation correction table and the display unit Will not display any faulty video. For example, in a display device capable of displaying 256 gradations, a gradation correction table for 64 gradations is stored, and when displaying an image, the gradation correction table for 64 gradations is displayed on the 256th floor. If the tone correction table for adjustment is modified, it is only necessary to store a tone correction table with a low tone level in the storage unit, so that the storage capacity can be saved, and a plurality of (many) tone correction tables can be stored. Can be remembered. Further, when displaying an image, an excellent effect is obtained such that the color reproducibility is not inferior because it is corrected to a gradation correction table having a high gradation.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.

(Embodiment 1)
FIG. 1 is a block diagram showing an example of a system including a configuration of a display device on which a video determination device according to Embodiment 1 of the present invention is mounted.
The display device 1 according to the first embodiment of the present invention includes a control unit 10 composed of a CPU. The control unit 10 is connected to the ROM 11, RAM 12, communication unit 13, operation unit 14, video signal input unit 15, video signal output unit (display unit) 16, storage unit 17, and data processing unit 18, and controls these units. Various functions are executed in accordance with a computer program stored in the ROM 11 in advance.

  The ROM 11 is a nonvolatile memory that is difficult to rewrite, and the ROM 11 has a difference between output levels corresponding to two input levels (here, adjacent input levels) of a gradation correction table for correcting the signal level of the video signal. Calculating the difference value, determining whether the gradation correction table is abnormal based on the difference value, and correcting the gradation when it is determined that the gradation correction table is abnormal A computer program is stored that includes the step of modifying the table. The RAM 12 stores temporary data generated when the control unit 10 executes the computer program, and is configured by, for example, a DRAM or an SDRAM.

  The communication unit 13 is for connecting to the gradation correction table creation device 5 via a connection cable, and is a gradation correction table for correcting the signal level of the video signal between the gradation correction table creation devices 5. Data transmission / reception is performed. Here, the connection is made through a simple connection cable, but it may be connected through a communication network such as a LAN. The gradation correction table creation device 5 is a device that creates a gradation correction table by a user. The gradation correction table is a reference table in which the gradation (output level) of the output video is uniquely determined by the gradation (input level) of the input video, and is defined using the look-up table. To do.

  The operation unit 14 includes various function keys for operating the display device 1. The function key characteristic of the present invention is the correction processing execution key 14a. When the correction processing execution key 14a is pressed by the user, it is determined whether or not the gradation correction table is abnormal. If it is determined, correction processing is executed.

  The video signal input unit 15 is connected to an antenna, for example, and takes in the video signal to the display device 1. The display unit 16 is a display device such as a liquid crystal display or an LED display. In addition, it is also possible to substitute a part or all of the various function keys of the operation unit 14 by using the display unit 16 as a touch panel system.

  The storage unit 17 is a first storage unit 17a for storing one or a plurality of gradation correction tables (standard gradation correction tables) created by the manufacturer of the display device 1 in advance for the display device. The second storage unit 17b for storing one or a plurality of gradation correction tables (user gradation correction tables) uniquely created by the user. The first storage unit 17a is configured by a non-rewritable nonvolatile memory such as a mask ROM so that the user cannot rewrite it without permission. Of course, the first storage unit 17a and the ROM 11 may be shared. On the other hand, the second storage unit 17b is configured by a non-volatile memory that can be easily rewritten. A non-volatile memory that can be easily rewritten is a so-called flash memory such as an EEPROM, for example, and can retain stored information even when power supply is cut off.

  For example, the gradation correction table transmitted from the gradation correction table creation device 5 is stored in the second storage unit 17b as a user gradation correction table. Alternatively, the standard gradation correction table stored in the first storage unit 17a may be read out and stored as the user gradation correction table in the second storage unit 17b.

  The data processing unit 18 corresponds to the video determination device according to the present invention, determines whether or not the gradation correction table (here, the user gradation correction table) stored in the storage unit 17 is abnormal, Is a block for correcting the gradation correction table when it is determined that the difference processing unit 18a, the determination processing unit 18b, and the correction processing unit 18c are provided.

  The difference processing unit 18a calculates a difference value between output levels corresponding to two input levels of the gradation correction table set by the user. For example, for each input level in the gradation correction table corresponding to the correction curve, a difference value between the input level and the adjacent output level is calculated (FIG. 2). For example, when the output level for the input level 209 is 910, the output level for the input level 210 is 900, and the output level for the input level 211 is 918, the difference value between the input levels 209 and 210 is −10, and between the input levels 210 and 211 The difference value of +18 is calculated.

  The determination processing unit 18b determines whether or not the gradation correction table is abnormal based on the difference value of each input level of the gradation correction table calculated by the difference processing unit 18a. Generally, when the difference value is positive, it can be seen that the correction curve corresponding to the gradation correction table is rising to the right, and when the difference value is negative, the correction curve is falling to the right. Therefore, it is possible to determine whether or not the gradation correction table is abnormal based on the calculated difference value. In this example, when the difference value is negative, it is determined that the gradation correction table is abnormal. The correction processing unit 18c corrects the gradation correction table when it is determined that the gradation correction table is abnormal.

  In this example, when it is determined that the gradation correction table is abnormal, the gradation correction table is corrected by performing a smoothing process using a moving average. By the way, when the tone correction table is simply smoothed, the upper limit (input level: 256) and lower limit (input level: 0) output levels of the tone correction table are changed. The table may get worse. Therefore, in this example, even if smoothing processing is performed, the upper and lower output levels of the gradation correction table are not changed.

Next, a specific example of the smoothing process will be described. Data _{y 0, y 1, y 2} , ..., y N ( total number of data is (N + 1)), the data number of the moving average is 2M + 1: case of the (M is a natural number), data after the moving average of the data y _n Y _n Is expressed as (Equation 1).

Thereby, for example, the data Y _{N-M + 1} after the moving average of the data y _{N-M + 1} is expressed as (Equation 2).

By the way, the third term of the numerator of (Formula 2) does not actually exist because it becomes (y _{N−M + 2} ) + (y _{N−M + 3} ) +... + (Y _{N + 1} ). Data y _{N + 1} will be included. Similarly, for the data up to _{Y N-M + 1 ~Y N} , necessary to calculate the moving average data _{y N + 1, y N +} 2, ..., there is no y _{N + M.}

Therefore, to calculate the data _{y N + 1, y N +} 2, ..., y N + M to add virtually, data after the moving average Y _{N-M + 1} ~Y _N, such as (Equation 3) .

As shown in FIG. 3, this virtual data is added by adding data before y _N (data y _NM , y _{N-M + 1} ,..., Y _N-1 : black circle in FIG. 3) to y _N. This is equivalent to disposing at a point-symmetrically projected position (white circle in FIG. 3). Since y _{N + 1} = y _N + A1 ′, A1 = A1 ′, and A1 = y _N −y _N−1 , y _{N + 1} = y _N + (y _N −y _N−1 ) , Y _{N + 1} = 2y _N −y _N−1 . Moreover, a _{y N + 2 = y N +} A2', A2 = A2', and because it is _{A2 = y N -y N-2} , y N + 2 = y N + (y N -y N-2 ) And y _{N + 2} = 2y _N −y _N−2 . Similarly, since y _{N + M} = y _N + AM ′, AM = AM ′, and AM = y _N −y _NM , y _{N + M} = y _N + (y _N −y _NM ) , Y _{N + M} = 2y _N −y _NM

Exactly the same applies to the other end point, that is, Y ₀ . That is, as shown in FIG. 4, the virtual data _{y -1, y -2, ...,} y -M: a black circle) in FIG. 4 is disposed at a position obtained by projecting the point symmetry with respect to y ₀ (in FIG. 4 White circle). Since y ₋₁ = y ₀ + B1 ′, B1 = B1 ′, and B1 = y ₀ −y ₁ , y ₋₁ = y ₀ + (y ₀ −y ₁ ) and y ₋₁ = 2y ₀ −y ₁ Since y ₋₂ = y ₀ + B2 ′, B2 = B2 ′, and B2 = y ₀ −y ₂ , y ₋₂ = y ₀ + (y ₀ −y ₂ ), and y ₋₂ = 2y ₀ -y ₂ Similarly, since y _−M = y ₀ + BM ′, BM = BM ′, and BM = y ₀ −y _M , y _−M = y ₀ + (y ₀ −y _M ) and y the _-M = 2y ₀ -y _M. In this way, data y ₋₁ , y ₋₂ ,..., Y _−M like (Equation 4) are virtually added to calculate data Y _{0 to} Y _M−1 after moving average.

As described above, by adding virtual data, pseudo-continuity (smoothness) of data within the effective range (Y _{0 to} Y _N ) is guaranteed. In other words, when virtual data is not added in this example, the upper limit is Y _NM at the boundary, and the lower limit is Y _M at the boundary, and the data is pseudo-discontinuous (not smooth). End up.

Further, since the added virtual data is symmetric with respect to y ₀ and y _N , the end points of the data, that is, Y _N is equal to y _N and Y ₀ is equal to y ₀ . Since the end point is generally the limit (upper limit, lower limit) of the potential of the display device, the smoothing process of this example has a characteristic that it does not change from the original data even when moving average is performed. Is preferred.

Next, the operation of the display device according to the present invention configured as described above will be described.
FIG. 5 is a flowchart when the correction process of the gradation correction table is performed in the display device according to the first embodiment of the present invention.
Based on whether or not the correction process execution key 14a is pressed, the control unit 10 determines whether or not to perform the correction process on the gradation correction table (step S1). If the correction process is not performed (S1: NO), the process is terminated. If the correction process is performed (S1: YES), first, the number of correction processes is set to 0 in order to grasp the number of times of the following correction processes. Setting is performed (step S2), and output level difference processing corresponding to adjacent input levels in the target gradation correction table is performed (step S3).

  Then, it is determined whether or not the difference value at each data point (input level) subjected to the difference process is 0 or less (step S4). In the gradation correction table, since the output level is a curve that increases monotonously with respect to the input level, if the difference value at each data point is 0 or less, it is determined that the gradation correction table is abnormal. Can do.

  When it is determined that the difference value at each data point is positive (S4: NO), it is not possible to determine that the target gradation correction table is abnormal, so the process ends without performing the correction process. On the other hand, when it is determined that the difference value at each data point is 0 or less (S4: YES), it is determined whether or not the number of correction processes is equal to or less than the specified number N (step S5). If it is determined that there is (S5: YES), the target gradation correction table is corrected (step S6). Then, the number of correction processes is incremented (step S7), and the process returns to S3. That is, since the gradation correction table corrected in S6 is not always normal, the process returns to S3 to determine again whether or not the corrected gradation correction table is abnormal. .

  On the other hand, when it is determined that the number of correction processes exceeds the specified number N (S5: NO), the process ends without performing the correction process. That is, when the difference value is 0 or less, it can be determined that the target gradation correction table is abnormal, and thus correction processing is performed. However, the correction processing is smoothed using the original data. Since the meaning of the gradation correction table may be lost by repeating the process, the correction process is not performed when the number of correction processes exceeds the specified number N. The specified number N is set so that the setting can be appropriately changed according to the user's preference.

  As described above, according to the present embodiment, whether or not the gradation correction table is abnormal can be quickly determined by an extremely simple process of difference processing of output levels corresponding to two input levels of the gradation correction table. Can be determined. Conventionally, even when an image is displayed, depending on the signal pattern of the image signal, there is a possibility that the user cannot grasp the abnormality of the gradation correction table. Therefore, there is no such fear.

  In the present embodiment, the mode in which the signal level of the video signal is corrected based on the gradation correction table corresponding to the correction curve has been described. However, based on the correction curve in which the input level and the output level are associated with each other. In such a form that the signal level of the video signal is corrected, the output level of the correction curve is differentiated with the input level as shown in FIG. It can be seen that when the differential value is positive, the correction curve is rising to the right, and when the differential value is negative, the correction curve is decreasing to the right. In general, if the correction curve is not monotonously increasing (upward to the right) or monotonously decreasing (downward to the right), the reversal of light and dark will cause trouble in color reproduction. It is determined whether or not the curve is abnormal. Therefore, it is possible to quickly determine whether or not the correction curve is abnormal by an extremely simple process of differentiation of the correction curve (the same applies to the following embodiments).

(Embodiment 2)
FIG. 7 is a block diagram showing an example of the configuration of the video determination apparatus according to Embodiment 2 of the present invention. A computer program for realizing the function of the video determination apparatus by a computer is executed on a so-called general-purpose computer. This is the case.
The video determination apparatus 2 according to Embodiment 2 of the present invention includes a control unit 20 configured with a CPU. The control unit 20 is connected to the ROM 21, the RAM 22, the communication unit 23, the operation unit 24, the storage unit 25, and the data processing unit 26, controls these units, and executes various functions according to computer programs stored in the ROM 21 in advance. To do. The RAM 22 stores temporary data generated when the control unit 20 executes the computer program, and is configured by, for example, a DRAM, an SDRAM, or the like.

  The communication unit 23 is for connecting to the display device 6 via a connection cable, and transmits and receives data related to the gradation correction table for correcting the signal level of the video signal between the display devices 6. Here, the connection is made through a simple connection cable, but it may be connected through a communication network such as a LAN.

  The operation unit 24 includes various function keys for operating the display device 1, and the user can create a desired gradation correction table. A function key characteristic of the present invention is a correction processing execution key 24a. When the correction processing execution key 24a is pressed by the user, the correction processing of the created gradation correction table is executed. The storage unit 25 is for storing one or a plurality of gradation correction tables (user gradation correction tables) uniquely created by the user of the display device 6 using the operation unit 24.

  The data processing unit 26 determines whether or not the gradation correction table (for example, the user gradation correction table) stored in the storage unit 25 is abnormal. This is a block for correction processing, and includes a difference processing unit 26a, a determination processing unit 26b, and a correction processing unit 26c. Since the correction processing unit 26a, the determination processing unit 26b, and the correction processing unit 26c are the same as the correction processing unit 18a, the determination processing unit 18b, and the correction processing unit 18c of the first embodiment, the description thereof is omitted.

  As described above, according to the present embodiment, whether or not the gradation correction table is abnormal can be quickly determined by an extremely simple process of difference processing of output levels corresponding to two input levels of the gradation correction table. Can be determined. In addition, since it can be determined whether or not the gradation correction table is abnormal, the abnormal gradation correction table is not transmitted to the display device 6.

(Embodiment 3)
The display device according to Embodiment 3 of the present invention has the same configuration as that of the display device 1 according to Embodiment 1 (see FIG. 1). Embodiment 3 is a case where a gradation correction table for 64 gradations is created by the gradation correction table creation apparatus 5 in FIG. 1 and the created gradation correction table is given to the display device. Difference processing is performed on the output levels corresponding to the two input levels of the correction table, and it is determined whether the gradation correction table is abnormal based on the sign of the difference value at each point of the gradation correction table subjected to the difference processing. Further, when it is determined that the gradation correction table is abnormal, the gradation correction table is corrected.

In this example, when it is determined that the gradation correction table is abnormal, the gradation correction table is corrected by performing an interpolation process. FIG. 8 is an explanatory diagram for explaining the interpolation processing according to the third embodiment of the present invention.
First, 0 level of the given gradation correction table for 64 gradations is changed to 0 level at 256 gradations, 1 level of the gradation correction table for 64 gradations is changed to 4 levels at 256 gradations,. 63 levels in gradation are set to 252 levels in 256 gradations (FIG. 8: black circles).

  Next, polynomial approximation is performed using these data as data samples (FIG. 8: one-dot chain line). The order of the polynomial can be set as appropriate by the user. Then, unset data in the gradation correction table is added based on the polynomial calculated by polynomial approximation (FIG. 8: white circle). Of course, as the interpolation processing, polynomial approximation is performed. However, it is only necessary to calculate an approximation formula by linear approximation (also referred to as a first-order polynomial) and perform sampling processing as appropriate, and the types of interpolation processing are limited. It is not something.

  As described above, according to the present embodiment, the gradation correction table for 64 gradations is interpolated and corrected to the gradation correction table for 256 gradations, so that the displayed display capability is exhibited. Can do. In particular, when used as a display device, a gradation correction table for 64 gradations is stored in the first storage unit 17a, this gradation correction table is read, and correction processing is executed as described above for 256 gradations. The tone correction table is created and stored in the second storage unit 17b, and the video signal is corrected based on the tone correction table for 256 tones stored in the second storage unit 17b. Since the memory capacity of the first storage unit 17a can be reduced, the cost of the apparatus can be reduced.

  In each embodiment, the case where the data processing unit 18 (26) includes the difference processing unit 18a (26a), the determination processing unit 18b (26b), and the correction processing unit 18c (26c) has been described. A data processing unit configured by 18a (26a) and a determination processing unit 18b (26b) determines whether or not the gradation correction table is abnormal by a very simple method called a difference between gradation correction tables. Can be widely used.

  In each embodiment, the gradation correction table is monotonously increased according to the input level. However, depending on the display device, there is a monotonous decrease. In this case, the difference value at each data point is determined. When is equal to or greater than 0, it is determined that the target gradation correction table is abnormal.

It is a block diagram which shows an example of the system containing the structure of the display apparatus by which the video determination apparatus which concerns on Embodiment 1 of this invention is mounted. It is explanatory drawing for demonstrating operation | movement of a difference process part. It is explanatory drawing for demonstrating the smoothing process by a moving average. It is explanatory drawing for demonstrating the smoothing process by a moving average. 6 is a flowchart in a case where a gradation correction table correction process is performed in the display device according to the first embodiment of the present invention. It is explanatory drawing about the case where it is determined whether a correction curve is abnormal by differentiation processing. It is a block diagram which shows an example of a structure of the image | video determination apparatus which concerns on Embodiment 2 of this invention. It is explanatory drawing for demonstrating the interpolation process which concerns on Embodiment 3 of this invention. It is a figure which shows an example of a correction curve and a gradation correction table. It is a figure which shows an example at the time of abnormality of a gradation correction table. It is a figure which shows the malfunction example of a display apparatus. It is a figure which shows an example at the time of abnormality of a gradation correction table.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,6 Display apparatus 2 Image | video determination apparatus 5 Gradation correction table preparation apparatus 10,20 Control part 11,21 ROM
12,22 RAM
13, 23 Communication unit 14, 24 Operation unit 14a, 24a Correction processing execution key 15 Video signal input unit 16 Video signal output unit (display unit)
17, 25 Storage unit 17a First storage unit 17b Second storage unit 18, 26 Data processing unit 18a, 26a Difference processing unit 18b, 26b Determination processing unit 18c, 26c Correction processing unit

Claims (10)

Differential processing means for differentiating the output level of the correction curve in which the input level and the output level are associated with each other in order to correct the signal level of the video signal;
And a determination unit that determines whether or not the correction curve is abnormal based on whether the differential value is positive or negative. The correction curve corresponds to one gradation,
The video determination apparatus according to claim 1, wherein the differential processing unit performs differential processing when the correction curve is made to correspond to another gradation level. The video determination apparatus according to claim 1, further comprising: a unit that corrects the correction curve when the correction curve is determined to be abnormal. A difference calculating means for calculating a difference value between the output levels corresponding to the two input levels of the gradation correction table in which the input level and the output level are associated with each other in order to correct the signal level of the video signal;
An image determination apparatus comprising: means for determining whether or not the gradation correction table is abnormal based on whether the calculated difference value is positive or negative. The gradation correction table corresponds to one gradation degree,
The video determination apparatus according to claim 4, wherein the difference calculation unit calculates a difference value when the gradation correction table is associated with another gradation degree. 6. The video determination apparatus according to claim 4, further comprising means for correcting the gradation correction table when the gradation correction table is determined to be abnormal. Video signal acquisition means for acquiring a video signal;
The video determination device according to claim 3,
Correction means for correcting the signal level of the video signal acquired by the video signal acquisition means based on the correction curve corrected by the video determination device;
A display device comprising: a display unit that displays an image related to a video signal in which the correction means corrects the signal level. Video signal acquisition means for acquiring a video signal;
The video determination device according to claim 6;
Correction means for correcting the signal level of the video signal acquired by the video signal acquisition means based on a gradation correction table corrected by the video determination device;
A display device comprising: a display unit that displays an image related to a video signal in which the correction means corrects the signal level. A computer program for determining whether a correction curve associated with an input level and an output level is abnormal in order to correct a signal level of a video signal,
Causing the computer to differentiate the output level of the correction curve at the input level;
And causing the computer to determine whether or not the correction curve is abnormal based on whether the differential value is positive or negative. A computer program for determining whether or not a gradation correction table in which an input level and an output level are associated with each other in order to correct a signal level of a video signal,
Causing a computer to calculate a difference value between output levels corresponding to two input levels of the gradation correction table;
And causing the computer to determine whether or not the gradation correction table is abnormal based on whether the difference value is positive or negative.

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