WO2014162555A1 - Display device, greyscale correction device, greyscale correction method, and greyscale correction program - Google Patents

Display device, greyscale correction device, greyscale correction method, and greyscale correction program Download PDF

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WO2014162555A1
WO2014162555A1 PCT/JP2013/060309 JP2013060309W WO2014162555A1 WO 2014162555 A1 WO2014162555 A1 WO 2014162555A1 JP 2013060309 W JP2013060309 W JP 2013060309W WO 2014162555 A1 WO2014162555 A1 WO 2014162555A1
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unit
luminance
value
correction
display
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PCT/JP2013/060309
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French (fr)
Japanese (ja)
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勝之 松井
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Ｎｅｃディスプレイソリューションズ株式会社
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Priority to PCT/JP2013/060309 priority Critical patent/WO2014162555A1/en
Publication of WO2014162555A1 publication Critical patent/WO2014162555A1/en

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0673—Adjustment of display parameters for control of gamma adjustment, e.g. selecting another gamma curve
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00—Aspects of the architecture of display systems
    • G09G2360/14—Detecting light within display terminals, e.g. using a single or a plurality of photosensors
    • G09G2360/145—Detecting light within display terminals, e.g. using a single or a plurality of photosensors the light originating from the display screen
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2380/00—Specific applications
    • G09G2380/08—Biomedical applications

Definitions

  • the present invention particularly relates to a display device, a gradation correction device, a gradation correction method, and a gradation correction program suitable for use in medical applications.
  • the DICOM gradation characteristic is defined as a luminance value with respect to a JND (Just Noticeable Difference) index value.
  • the JND index value is an input value in which one step is a human luminance discrimination area.
  • a high luminance characteristic is required in order to efficiently find a fine lesion.
  • GSDF Gramscale Standard Display Function
  • DICOM DICOM
  • a display device for medical use is required to have gradation characteristics that match the DICOM curve.
  • the maximum error between the gradation characteristic curve of the display device and the DICOM curve is called MaxGSDF ErrorRate.
  • gradation characteristics are calibrated so that gradation characteristics that match the DICOM curve can be obtained.
  • gamma characteristics are set in advance based on the set unique JND index value.
  • the luminance value is detected by the JND index value of the eigenvalue.
  • the power of the backlight is adjusted so that the detected luminance value at the eigenvalue JND index value matches the luminance value on the DICOM curve.
  • a display device for medical use is required to achieve both high luminance display and high accuracy display. Specifically, it is desired that a high JND index value can be input and MaxGSDF ErrorRate is low.
  • the present invention provides a display device, a gradation correction device, a gradation correction method, and a gradation correction program capable of achieving both high luminance display and high accuracy display. With the goal.
  • a display device that is one embodiment of the present invention drives a display unit that displays an image, a light irradiation unit that irradiates backlight light to the display unit, and a light irradiation unit with a fixed value.
  • Drive unit screen luminance detection unit for detecting a luminance value corresponding to the luminance of the display unit, gradation correction unit for correcting gradation characteristics of the input video signal, and screen luminance detection unit detected at a predetermined cycle
  • a correction value calculation unit configured to calculate a gradation correction characteristic based on the luminance value and set the gradation correction unit.
  • a gradation correction device includes a screen luminance detection unit that detects a luminance value corresponding to the luminance of the display unit when the light source of the display unit is driven with a fixed value.
  • a gradation correction unit that corrects the gradation characteristic of the input video signal, and a correction value calculation unit that calculates the gradation correction characteristic based on the luminance value in a predetermined cycle and sets the gradation correction unit. It is characterized by that.
  • the gradation correction method drives the light for the display portion with a fixed value and corresponds to the luminance of the display portion when the light source of the display portion is driven with a fixed value. And a tone correction characteristic is calculated on the basis of the luminance value at a predetermined cycle, and tone correction of the input video signal is performed.
  • a gradation correction program includes a step of driving light to a display unit with a fixed value, and a luminance of the display unit when the light source of the display unit is driven with a fixed value. And a step of calculating a gradation correction characteristic based on the luminance value in a predetermined cycle.
  • FIG. 1 is a block diagram showing the basic configuration of the present invention.
  • the basic configuration of the present invention includes a display unit 501, a light irradiation unit 502, a drive unit 503, a luminance detection unit 504, a gradation correction unit 505, and a correction value calculation unit 506. It has.
  • Display unit 501 displays an image.
  • the light irradiation unit 502 is a light source of the display unit 501.
  • the drive unit 503 drives the light irradiation unit 502 with a fixed value.
  • the luminance detection unit 504 detects a luminance value corresponding to the luminance of the display unit 501.
  • a gradation correction unit 505 corrects gradation characteristics of the input video signal.
  • the correction value calculation unit 506 calculates a gradation correction characteristic based on the luminance detection value detected by the luminance detection unit 504 and sets the gradation correction characteristic in the gradation correction unit 505.
  • FIG. 2 is a block diagram illustrating a configuration of the display device according to the present embodiment.
  • the display device 1 according to the present embodiment includes an input unit 11, a gamma correction unit 12, a reference video generation unit 13, a display unit 14, a backlight 15, and a backlight driving unit 16. And a screen brightness detector 17 and a correction value calculator 18.
  • the input unit 11 inputs a video signal from the external device 2.
  • This input video signal is a video signal of an image for medical diagnosis, for example, an image such as CT (Computed Tomography) or MRI (magnetic resonance Imaging).
  • the gamma correction unit 12 performs gradation correction on the input video signal so as to conform to the DICOM curve.
  • FIG. 3 shows the gradation characteristics determined by DICOM.
  • the horizontal axis indicates the JND index value
  • the vertical axis indicates the luminance (cd / m 2 ).
  • FIG. 4 shows the correspondence between JND index values and luminance.
  • the gamma correction unit 12 corrects the gradation of the input video signal so that the gradation of the displayed video signal becomes the gradation characteristic of the DICOM curve shown in FIGS.
  • the gamma correction value in the gamma correction unit 12 is set by the correction value calculation unit 18.
  • the reference image generation unit 13 generates a reference image signal such as white.
  • the display unit 14 displays an image corresponding to the video signal input to the input unit 11 or the reference video signal generated from the reference video generation unit 13.
  • an LCD Liquid Crystal Display
  • the backlight 15 irradiates the display unit 14 with backlight light.
  • the backlight drive unit 16 drives the backlight 15. In the present embodiment, the backlight drive unit 16 drives the backlight 15 with a fixed value that maximizes the optical power, for example.
  • the screen brightness detection unit 17 detects the screen brightness of the display unit 14.
  • the screen luminance detection unit 17 is attached to the end of the screen so as not to obstruct display.
  • the display unit 14 displays the white test signal in a small area including the detection area of the screen brightness detection unit 17.
  • the correction value calculation unit 18 determines a JND index value corresponding to the luminance value from the luminance value detected by the screen luminance detection unit 17, and uses the JND index value corresponding to the luminance value as the maximum luminance value, so that the DICOM curve A gamma correction value, which is a tone correction characteristic that satisfies the following, is calculated and set in the gamma correction unit 12.
  • FIG. 5 is a flowchart of gradation characteristic correction processing in the display device according to the present embodiment.
  • the backlight driving unit 16 sets the backlight 15 to the maximum power during the display operation (step S1).
  • the reference video generation unit 13 displays a white image in a small area including the detection area of the screen luminance detection unit 17 provided at the end of the display unit 14 (step S2). This white image may be displayed constantly.
  • the screen brightness detection unit 17 detects the screen brightness of the display unit 14 when the backlight 15 is driven at the maximum power (step S3). Note that the luminance detection may be always performed.
  • the correction value calculation unit 18 determines a JND index value corresponding to the detected value of luminance from the detected value of the luminance of the screen of the display unit 14 when the backlight 15 is driven at the maximum power by using a DICOM curve (Step S1). S4).
  • the detected value of the luminance of the display unit 14 when the backlight 15 is driven at the maximum power and a white image is displayed on the display unit 14 is 933 cd / m 2 .
  • the correction value calculation unit 18 sets the determined JND index value as the maximum luminance value, calculates a gamma characteristic that matches the DICOM curve (step S5), and sets it in the gamma correction unit 12 (step S6). .
  • a calculation method for obtaining the gamma characteristic is known, and is described in, for example, Patent Document 1.
  • the above-described processing is repeatedly executed at a predetermined cycle during the display operation. That is, the processing from step S4 to step S6 is repeatedly executed at a predetermined cycle. Since the change in luminance with time is relatively slow, the predetermined period is, for example, one hour. Steps S2 and S3 may be performed all the time, or may be performed at a cycle shorter than a predetermined cycle.
  • the backlight drive unit 16 drives the backlight 15 with the eigenvalue of the maximum power
  • the screen brightness detection unit 17 drives the backlight 15 with the maximum power.
  • the brightness is detected.
  • the correction value calculation unit 18 determines the JND index value corresponding to the luminance value from the detected luminance value, sets the JND index value corresponding to the luminance value as the maximum luminance value, and sets the JND index value to the DICOM curve.
  • a gamma correction value that matches is calculated.
  • FIG. 6 shows a calibration by using a unique JND index value to set a gamma correction value in advance, and adjusting the backlight power so that the detected luminance value matches the luminance value in the DICOM curve, thereby correcting the gradation. It is an example of a structure of the display apparatus which performs.
  • 2 includes the input unit 11, the gamma correction unit 12, the reference video generation unit 13, the display unit 14, the backlight 15, the backlight driving unit 16, the screen luminance detection unit 17, and the correction value calculation.
  • a video signal from the external device 102 is input to the input unit 111.
  • the correction value setting unit 118 sets a unique JND index value at the time of calibration, obtains a gamma characteristic that matches the DICOM curve, and sets it in the gamma correction unit 112 in advance. Therefore, the gamma characteristic of the gamma correction unit 112 is a fixed value. Then, during the display operation, the screen luminance detection unit 117 detects the luminance value of the display unit 14 with the unique JND index value, and the backlight driving unit 116 converts the luminance detection value into the luminance value on the DICOM curve. The power of the backlight 115 is adjusted so as to match. Therefore, the power of the backlight 115 is changed following the detected luminance value.
  • the display device 1 according to the present invention shown in FIG. 2 drives the backlight 15 at a fixed value that provides the maximum power.
  • the screen luminance detection unit 17 detects the luminance of the screen of the display unit 14, and the correction value calculation unit 18 determines a JND index value corresponding to the luminance value from the luminance value detected by the screen luminance detection unit 17. . Then, the correction value calculation unit 18 sets the determined JND index value as the maximum luminance value, obtains a gamma characteristic that matches the DICOM curve, and sets it in the gamma correction unit 12. Therefore, the characteristic of the gamma correction unit 12 is changed following the detected luminance value.
  • the horizontal axis indicates the usage time
  • the vertical axis indicates the luminance converted with the JND index value.
  • the gamma correction unit 112 is set.
  • the display device 101 as shown in FIG. 6 cannot increase the eigenvalue of the JND index set as the maximum value when performing calibration, and it is difficult to achieve both high luminance display and high accuracy display. .
  • high luminance display is possible at the beginning, but due to the luminance deterioration, for example, about 30,000.
  • MaxGSDF ErrorRate will exceed 10%.
  • the display device 1 according to the embodiment of the present invention can display up to the maximum luminance at which the backlight 15 has the maximum power, and can perform high luminance display.
  • the display device 1 according to the embodiment of the present invention detects the luminance of the screen at a predetermined cycle, determines the JND index value corresponding to the detected luminance, and calculates the gamma characteristic. Therefore, even if the characteristics of the display device 1 change due to changes over time, the gamma characteristics of the gamma correction unit 12 are changed according to the change characteristics. For this reason, MaxGSDF ErrorRate does not deteriorate significantly due to a change with time.
  • the maximum luminance value when calculating the gamma correction value is always a JND index value corresponding to the luminance value when the backlight 15 has the maximum power. .
  • the display device 1 according to the present embodiment enables high-luminance display.
  • the gamma characteristic of the gamma correction unit 12 is updated following the detected luminance value of the display unit 14. For this reason, even if the luminance characteristics of the display unit 14 deteriorate due to a change over time, the MaxGSDF ErrorRate does not deteriorate and high-precision display can be maintained. Further, in the display device 1 according to the present embodiment, since the gamma characteristic of the gamma correction unit 12 is updated according to the decrease in luminance, recalibration is unnecessary.
  • JND index 670
  • the display device 1 according to the present embodiment can achieve both high luminance display and high accuracy display.
  • the backlight 15 is set to a fixed value of the maximum power.
  • the fixed value set to the backlight 15 may not be the maximum power, and may be a constant value or a temperature limit value. .
  • the screen brightness detection unit 17 detects the brightness of the display unit 14.
  • the brightness of the backlight 15 may be detected.
  • luminance of the backlight 15 a white screen is unnecessary.
  • a program for realizing the control function is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed by the computer system. Also good.
  • This computer system includes an operating system (OS) and hardware of peripheral devices.
  • the computer-readable recording medium is a portable recording medium such as a flexible disk, a magneto-optical disk, an optical disk, or a memory card, and a storage device such as a magnetic hard disk or a solid state drive provided in the computer system.
  • a computer-readable recording medium holds a program dynamically for a short time, such as a computer network such as the Internet, and a communication line when transmitting a program via a telephone line or a cellular phone network.
  • a server that holds a program for a certain period of time, such as a volatile memory inside a computer system serving as a server device or a client in that case, may be included.
  • the above program may be for realizing a part of the above-described functions, and further, may be realized by combining the above-described functions with a program already recorded in the computer system. Good.

Abstract

The present invention is equipped with a display unit (501), a light irradiation unit (502), a drive unit (503), a brightness detection unit (504), a greyscale correction unit (505), and a correction value calculation unit (506). The display unit (501) displays images. The light irradiation unit (502) irradiates the display unit (501) with light. The drive unit (503) drives the light irradiation unit (502) at a fixed value. The brightness detection unit (504) detects the brightness of the display unit (501). The greyscale correction unit (505) corrects the greyscale characteristic of an input video signal. The correction value calculation unit (506) calculates the greyscale correction characteristic on the basis of the detection value of the brightness detected by the brightness detection unit (504), and sets the greyscale correction characteristic in the greyscale correction unit (505).

Description

表示装置、階調補正装置、階調補正方法、及び階調補正プログラムDisplay device, gradation correction device, gradation correction method, and gradation correction program
　本発明は、特に、医療用途向けとして用いて好適な表示装置、階調補正装置、階調補正方法、及び階調補正プログラムに関する。 The present invention particularly relates to a display device, a gradation correction device, a gradation correction method, and a gradation correction program suitable for use in medical applications.
　医療用途向け表示装置では、正確な診断を行うために、ＤＩＣＯＭ（Digital Imaging and COmmunicationin Medicine）により定められた階調特性で、精度の高い画像表示を行うことが要望される。ＤＩＣＯＭの階調特性は、特許文献１及び特許文献２に示されるように、ＪＮＤ（Just Noticeable Difference ）インデックス値に対する輝度値として定められている。ＪＮＤインデックス値は、１ステップが人間の輝度の弁別域となるような入力値である。医療用途向け表示装置では、例えば微細な病巣を効率よく発見するために、高輝度特性が要望される。 In a display device for medical use, in order to perform an accurate diagnosis, it is required to display an image with high accuracy with gradation characteristics determined by DICOM (Digital Imaging and COmmunicationin Medical). As shown in Patent Document 1 and Patent Document 2, the DICOM gradation characteristic is defined as a luminance value with respect to a JND (Just Noticeable Difference) index value. The JND index value is an input value in which one step is a human luminance discrimination area. In a display device for medical use, for example, a high luminance characteristic is required in order to efficiently find a fine lesion.
　ＤＩＣＯＭの階調特性を示す関数は、ＧＳＤＦ（Grayscale Standard Display Function）と呼ばれている。このような階調特性のカーブは、一般的に、ＤＩＣＯＭカーブと呼ばれている。医療用途向け表示装置では、ＤＩＣＯＭカーブと合致した階調特性が要求される。また、表示装置の階調特性のカーブとＤＩＣＯＭカーブとの最大誤差は、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅと呼ばれている。 A function indicating the gradation characteristics of DICOM is called GSDF (Grayscale Standard Display Function). Such a gradation characteristic curve is generally called a DICOM curve. A display device for medical use is required to have gradation characteristics that match the DICOM curve. The maximum error between the gradation characteristic curve of the display device and the DICOM curve is called MaxGSDF ErrorRate.
　医療用途向け表示装置では、ＤＩＣＯＭカーブと合致した階調特性が得られるように、階調特性のキャリブレーションが行われる。キャリブレーションでは、設定された固有のＪＮＤインデックス値に基づいて、ガンマ特性が予め設定される。表示動作中では、固有値のＪＮＤインデックス値で輝度値が検出される。そして、この固有値のＪＮＤインデックス値での輝度の検出値がＤＩＣＯＭカーブでの輝度値と合致するように、バックライトのパワーが調整される。 In a display device for medical use, gradation characteristics are calibrated so that gradation characteristics that match the DICOM curve can be obtained. In the calibration, gamma characteristics are set in advance based on the set unique JND index value. During the display operation, the luminance value is detected by the JND index value of the eigenvalue. Then, the power of the backlight is adjusted so that the detected luminance value at the eigenvalue JND index value matches the luminance value on the DICOM curve.
特開２００７－１１４４２７号公報JP 2007-114427 A 特開２００４－２０８０１７号公報JP 2004-208017 A
　上述のように、医療用途向け表示装置では、高輝度表示と高精度表示との両立を図ることが求められている。具体的には、高ＪＮＤインデックス値の入力が可能で、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅが低いことが要望される。 As described above, a display device for medical use is required to achieve both high luminance display and high accuracy display. Specifically, it is desired that a high JND index value can be input and MaxGSDF ErrorRate is low.
　キャリブレーションを行う際に最大輝度値として設定する固有のＪＮＤインデックス値を高くすると、高輝度表示が可能になる。しかしながら、表示装置には経時変化があり、表示装置の輝度特性は、時間の経過と共に劣化する。このため、表示装置で表示可能な最大輝度値が、最大輝度値として設定した固有のインデックス値の輝度値以下まで劣化すると、ＤＩＣＯＭカーブと合致した階調特性が得られなくなり、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅが悪化する。このため、通常では、経時変化を考慮して、最大輝度値として設定する固有のＪＮＤインデックス値の輝度値を、表示装置が表示可能な最大輝度値よりも低く設定している。このため、高輝度の表示を行うことが難しい。 ・ Higher brightness display is possible by increasing the unique JND index value that is set as the maximum brightness value during calibration. However, the display device changes with time, and the luminance characteristics of the display device deteriorate with the passage of time. For this reason, if the maximum luminance value that can be displayed on the display device deteriorates to a value equal to or less than the luminance value of the unique index value set as the maximum luminance value, gradation characteristics that match the DICOM curve cannot be obtained, and MaxGSDF ErrorRate deteriorates. . For this reason, normally, the luminance value of the unique JND index value set as the maximum luminance value is set lower than the maximum luminance value that can be displayed by the display device in consideration of the change with time. For this reason, it is difficult to display with high luminance.
　なお、表示装置の経時変化により表示装置の輝度が低下した場合には、最大輝度値として設定する固有のＪＮＤインデックス値を下げて、再キャリブレーションを行い、ガンマ特性を設定し直すことが考えられる。しかしながら、再キャリブレーションを行うのでは、管理コストが上昇する。 When the luminance of the display device decreases due to the change of the display device over time, it is conceivable to lower the unique JND index value set as the maximum luminance value, perform recalibration, and reset the gamma characteristic. . However, performing recalibration increases the management cost.
　上述の課題を鑑み、本発明は、高輝度表示と高精度表示との両立を図ることができるようにした表示装置、階調補正装置、階調補正方法、及び階調補正プログラムを提供することを目的とする。 In view of the above-described problems, the present invention provides a display device, a gradation correction device, a gradation correction method, and a gradation correction program capable of achieving both high luminance display and high accuracy display. With the goal.
　上記の課題を解決するため、本発明の一態様である表示装置は、画像を表示する表示部と、表示部に対するバックライト光を照射する光照射部と、光照射部を固定値で駆動する駆動部と、表示部の輝度に対応する輝度値を検出する画面輝度検出部と、入力映像信号の階調特性を補正する階調補正部と、所定の周期で画面輝度検出部で検出された輝度値に基づいて階調補正特性を算出し、階調補正部に設定する補正値算出部と、を具備することを特徴とする。 In order to solve the above problems, a display device that is one embodiment of the present invention drives a display unit that displays an image, a light irradiation unit that irradiates backlight light to the display unit, and a light irradiation unit with a fixed value. Drive unit, screen luminance detection unit for detecting a luminance value corresponding to the luminance of the display unit, gradation correction unit for correcting gradation characteristics of the input video signal, and screen luminance detection unit detected at a predetermined cycle And a correction value calculation unit configured to calculate a gradation correction characteristic based on the luminance value and set the gradation correction unit.
　上記の課題を解決するため、本発明の一態様である階調補正装置は、表示部の光源を固定値で駆動したときの表示部の輝度に対応する輝度値を検出する画面輝度検出部と、入力映像信号の階調特性を補正する階調補正部と、所定の周期で輝度値に基づいて階調補正特性を算出し、階調補正部に設定する補正値算出部と、を具備することを特徴とする。 In order to solve the above problems, a gradation correction device according to an aspect of the present invention includes a screen luminance detection unit that detects a luminance value corresponding to the luminance of the display unit when the light source of the display unit is driven with a fixed value. A gradation correction unit that corrects the gradation characteristic of the input video signal, and a correction value calculation unit that calculates the gradation correction characteristic based on the luminance value in a predetermined cycle and sets the gradation correction unit. It is characterized by that.
　上記の課題を解決するため、本発明の一態様である階調補正方法は、表示部に対する光を固定値で駆動し、表示部の光源を固定値で駆動したときの表示部の輝度に対応する輝度値を検出し、所定の周期で輝度値に基づいて階調補正特性を算出して、入力映像信号の階調補正を行うことを特徴とする。 In order to solve the above-described problem, the gradation correction method according to one embodiment of the present invention drives the light for the display portion with a fixed value and corresponds to the luminance of the display portion when the light source of the display portion is driven with a fixed value. And a tone correction characteristic is calculated on the basis of the luminance value at a predetermined cycle, and tone correction of the input video signal is performed.
　上記の課題を解決するため、本発明の一態様である階調補正プログラムは、表示部に対する光を固定値で駆動するステップと、表示部の光源を固定値で駆動したときの表示部の輝度に対応する輝度値を検出するステップと、所定の周期で輝度値に基づいて階調補正特性を算出するステップと、を含むことを特徴とする。 In order to solve the above problems, a gradation correction program according to one embodiment of the present invention includes a step of driving light to a display unit with a fixed value, and a luminance of the display unit when the light source of the display unit is driven with a fixed value. And a step of calculating a gradation correction characteristic based on the luminance value in a predetermined cycle.
　本発明によれば、高輝度表示と高精度表示との両立が可能になる。 According to the present invention, it is possible to achieve both high luminance display and high accuracy display.
本発明の基本構成を示すブロック図である。It is a block diagram which shows the basic composition of this invention. 本発明の一実施形態に係る表示装置の構成を示すブロック図である。It is a block diagram which shows the structure of the display apparatus which concerns on one Embodiment of this invention. ＤＩＣＯＭで定められた階調特性を示すグラフである。It is a graph which shows the gradation characteristic defined by DICOM. ＤＩＣＯＭで定められた階調特性のＪＤＮインデックスと輝度値との対応関係の説明図である。It is explanatory drawing of the correspondence of the JDN index of the gradation characteristic defined by DICOM, and a luminance value. 本発明の一実施形態に係る表示装置における階調特性の補正処理のフローチャートである。It is a flowchart of the correction process of the gradation characteristic in the display apparatus which concerns on one Embodiment of this invention. バックライトのパワーを調整して階調補正を行う表示装置の構成の一例のブロック図である。It is a block diagram of an example of the structure of the display apparatus which adjusts the power of a backlight and performs gradation correction. 経時変化による特性の説明に用いるグラフである。It is a graph used for description of the characteristic by a change with time. 経時変化による特性の説明に用いるグラフである。It is a graph used for description of the characteristic by a change with time.
　以下、本発明の実施の形態について図面を参照しながら説明する。図１は、本発明の基本構成を示すブロック図である。図１に示すように、本発明の基本構成は、表示部５０１と、光照射部５０２と、駆動部５０３と、輝度検出部５０４と、階調補正部５０５と、補正値算出部５０６とを具備する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the basic configuration of the present invention. As shown in FIG. 1, the basic configuration of the present invention includes a display unit 501, a light irradiation unit 502, a drive unit 503, a luminance detection unit 504, a gradation correction unit 505, and a correction value calculation unit 506. It has.
　表示部５０１は、画像を表示する。光照射部５０２は、表示部５０１の光源である。駆動部５０３は、光照射部５０２を固定値で駆動する。輝度検出部５０４は、表示部５０１の輝度に対応する輝度値を検出する。階調補正部５０５は、入力映像信号の階調特性を補正する。補正値算出部５０６は、輝度検出部５０４で検出された輝度の検出値に基づいて階調補正特性を算出し、階調補正部５０５に設定する。 Display unit 501 displays an image. The light irradiation unit 502 is a light source of the display unit 501. The drive unit 503 drives the light irradiation unit 502 with a fixed value. The luminance detection unit 504 detects a luminance value corresponding to the luminance of the display unit 501. A gradation correction unit 505 corrects gradation characteristics of the input video signal. The correction value calculation unit 506 calculates a gradation correction characteristic based on the luminance detection value detected by the luminance detection unit 504 and sets the gradation correction characteristic in the gradation correction unit 505.
　次に、本発明の実施の形態について説明する。図２は、本実施形態に係る表示装置の構成を示すブロック図である。図２に示すように、本実施形態に係る表示装置１は、入力部１１と、ガンマ補正部１２と、基準映像発生部１３と、表示部１４と、バックライト１５と、バックライト駆動部１６と、画面輝度検出部１７と、補正値計算部１８とを備えている。 Next, an embodiment of the present invention will be described. FIG. 2 is a block diagram illustrating a configuration of the display device according to the present embodiment. As shown in FIG. 2, the display device 1 according to the present embodiment includes an input unit 11, a gamma correction unit 12, a reference video generation unit 13, a display unit 14, a backlight 15, and a backlight driving unit 16. And a screen brightness detector 17 and a correction value calculator 18.
　入力部１１は、外部機器２からの映像信号を入力する。この入力映像信号は、医療診断用の画像の映像信号、例えば、ＣＴ（Computed Tomography）やＭＲＩ（magnetic resonance imaging）等の画像である。 The input unit 11 inputs a video signal from the external device 2. This input video signal is a video signal of an image for medical diagnosis, for example, an image such as CT (Computed Tomography) or MRI (magnetic resonance Imaging).
　ガンマ補正部１２は、ＤＩＣＯＭカーブに適合するように、入力映像信号に対して階調補正を行う。図３は、ＤＩＣＯＭで定められた階調特性を示すものである。この図において、横軸はＪＮＤインデックス値を示し、縦軸は輝度（ｃｄ／ｍ２）を示している。図４は、ＪＮＤインデックス値と輝度との対応関係を示している。ガンマ補正部１２は、表示される映像信号の階調が図３及び図４に示すＤＩＣＯＭカーブの階調特性となるように、入力映像信号の階調を補正する。ガンマ補正部１２でのガンマ補正値は、補正値計算部１８により設定される。 The gamma correction unit 12 performs gradation correction on the input video signal so as to conform to the DICOM curve. FIG. 3 shows the gradation characteristics determined by DICOM. In this figure, the horizontal axis indicates the JND index value, and the vertical axis indicates the luminance (cd / m 2 ). FIG. 4 shows the correspondence between JND index values and luminance. The gamma correction unit 12 corrects the gradation of the input video signal so that the gradation of the displayed video signal becomes the gradation characteristic of the DICOM curve shown in FIGS. The gamma correction value in the gamma correction unit 12 is set by the correction value calculation unit 18.
　基準映像発生部１３は、白色等の基準の映像信号を発生する。表示部１４は、入力部１１に入力された映像信号又は基準映像発生部１３から発生された基準映像信号に対応する画像を表示する。表示部１４としては、ＬＣＤ（Liquid Crystal Display）やプロジェクタが用いられる。バックライト１５は、表示部１４に対してバックライト光を照射する。バックライト駆動部１６は、バックライト１５を駆動する。本実施形態では、バックライト駆動部１６は、例えば光パワーが最大となる固定値でバックライト１５を駆動する。 The reference image generation unit 13 generates a reference image signal such as white. The display unit 14 displays an image corresponding to the video signal input to the input unit 11 or the reference video signal generated from the reference video generation unit 13. As the display unit 14, an LCD (Liquid Crystal Display) or a projector is used. The backlight 15 irradiates the display unit 14 with backlight light. The backlight drive unit 16 drives the backlight 15. In the present embodiment, the backlight drive unit 16 drives the backlight 15 with a fixed value that maximizes the optical power, for example.
　画面輝度検出部１７は、表示部１４の画面の輝度を検出する。画面輝度検出部１７は、表示の邪魔とならないように画面の端部に取り付けられている。画面の輝度を検出するために、表示部１４は、白色のテスト信号を画面輝度検出部１７の検出エリアを含む小領域に表示する。補正値計算部１８は、画面輝度検出部１７で検出された輝度値から、この輝度値に対応するＪＮＤインデックス値を判定し、この輝度値に対応するＪＮＤインデックス値を最大輝度値として、ＤＩＣＯＭカーブとなるような階調補正特性であるガンマ補正値を算出し、ガンマ補正部１２に設定する。 The screen brightness detection unit 17 detects the screen brightness of the display unit 14. The screen luminance detection unit 17 is attached to the end of the screen so as not to obstruct display. In order to detect the screen brightness, the display unit 14 displays the white test signal in a small area including the detection area of the screen brightness detection unit 17. The correction value calculation unit 18 determines a JND index value corresponding to the luminance value from the luminance value detected by the screen luminance detection unit 17, and uses the JND index value corresponding to the luminance value as the maximum luminance value, so that the DICOM curve A gamma correction value, which is a tone correction characteristic that satisfies the following, is calculated and set in the gamma correction unit 12.
　図５は、本実施形態に係る表示装置における階調特性の補正処理のフローチャートである。 FIG. 5 is a flowchart of gradation characteristic correction processing in the display device according to the present embodiment.
　図５において、バックライト駆動部１６は、表示動作中に、バックライト１５を最大パワーに設定する（ステップＳ１）。基準映像発生部１３は、表示部１４の端部に設けられた画面輝度検出部１７の検出エリアを含む小領域に白色画像を表示する（ステップＳ２）。なお、この白色画像は、常時表示していても良い。そして、画面輝度検出部１７は、バックライト１５を最大パワーで駆動したときの表示部１４の画面の輝度を検出する（ステップＳ３）。なお、輝度の検出は、常時行っても良い。補正値計算部１８は、バックライト１５を最大パワーで駆動したときの表示部１４の画面の輝度の検出値から、ＤＩＣＯＭカーブにより、この輝度の検出値に対応するＪＮＤインデックス値を判定する（ステップＳ４）。 In FIG. 5, the backlight driving unit 16 sets the backlight 15 to the maximum power during the display operation (step S1). The reference video generation unit 13 displays a white image in a small area including the detection area of the screen luminance detection unit 17 provided at the end of the display unit 14 (step S2). This white image may be displayed constantly. Then, the screen brightness detection unit 17 detects the screen brightness of the display unit 14 when the backlight 15 is driven at the maximum power (step S3). Note that the luminance detection may be always performed. The correction value calculation unit 18 determines a JND index value corresponding to the detected value of luminance from the detected value of the luminance of the screen of the display unit 14 when the backlight 15 is driven at the maximum power by using a DICOM curve (Step S1). S4).
　例えば、バックライト１５を最大パワーで駆動し、表示部１４に白色画像を表示したときの表示部１４の輝度の検出値が９３３ｃｄ／ｍ２であったとする。この場合、図３及び図４に示したＤＩＣＯＭカーブから、この輝度値に対応するＪＮＤインデックス値は、（JND index＝８００）であると判定できる。 For example, assume that the detected value of the luminance of the display unit 14 when the backlight 15 is driven at the maximum power and a white image is displayed on the display unit 14 is 933 cd / m 2 . In this case, it can be determined from the DICOM curves shown in FIGS. 3 and 4 that the JND index value corresponding to this luminance value is (JND index = 800).
　補正値計算部１８は、判定されたＪＮＤインデックス値を最大輝度値として設定して、ＤＩＣＯＭカーブと合致するようなガンマ特性を算出し（ステップＳ５）、ガンマ補正部１２に設定する（ステップＳ６）。すなわち、輝度の検出値が９３３ｃｄ／ｍ２であった場合、最大輝度値を（JND index＝８００）として設定し、ＤＩＣＯＭカーブと合致するようなガンマ特性を計算する。なお、ガンマ特性を求めるための算出方法については既知であり、例えば特許文献１に記載されている。上述の処理は、表示動作中、所定の周期で繰り返して実行される。すなわち、ステップＳ４からステップＳ６までの処理は、所定の周期で繰り返し実行される。輝度の経時的な変化は比較的緩やかなので、所定の周期は、例えば1時間である。ステップＳ２およびステップＳ３は、常時行っても良いし、所定の周期よりも短い周期で行っても良い。 The correction value calculation unit 18 sets the determined JND index value as the maximum luminance value, calculates a gamma characteristic that matches the DICOM curve (step S5), and sets it in the gamma correction unit 12 (step S6). . In other words, when the detected luminance value is 933 cd / m 2 , the maximum luminance value is set as (JND index = 800), and the gamma characteristic that matches the DICOM curve is calculated. Note that a calculation method for obtaining the gamma characteristic is known, and is described in, for example, Patent Document 1. The above-described processing is repeatedly executed at a predetermined cycle during the display operation. That is, the processing from step S4 to step S6 is repeatedly executed at a predetermined cycle. Since the change in luminance with time is relatively slow, the predetermined period is, for example, one hour. Steps S2 and S3 may be performed all the time, or may be performed at a cycle shorter than a predetermined cycle.
　このように、本実施形態に係る表示装置１では、バックライト駆動部１６は、バックライト１５を最大パワーの固有値で駆動し、画面輝度検出部１７は、バックライト１５を最大パワーで駆動したときの輝度を検出している。そして、補正値計算部１８は、検出された輝度値から、この輝度値に対応するＪＮＤインデックス値を判定し、この輝度値に対応するＪＮＤインデックス値を最大輝度値として設定して、ＤＩＣＯＭカーブに合致するようなガンマ補正値を算出している。そしてこれらの処理を表示動作中、所定の周期で繰り返し実行している。これにより、高輝度表示が可能になると共に、経時変化による輝度の低下が生じても、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅが悪化しない。このことについて、以下、本実施形態に係る表示装置１と、図６に示す構成の表示装置１０１とを対比しながら説明する。 Thus, in the display device 1 according to the present embodiment, the backlight drive unit 16 drives the backlight 15 with the eigenvalue of the maximum power, and the screen brightness detection unit 17 drives the backlight 15 with the maximum power. The brightness is detected. Then, the correction value calculation unit 18 determines the JND index value corresponding to the luminance value from the detected luminance value, sets the JND index value corresponding to the luminance value as the maximum luminance value, and sets the JND index value to the DICOM curve. A gamma correction value that matches is calculated. These processes are repeatedly executed at a predetermined cycle during the display operation. As a result, high-luminance display becomes possible, and MaxGSDF ErrorRate does not deteriorate even if the luminance is lowered due to change over time. This will be described below by comparing the display device 1 according to the present embodiment with the display device 101 having the configuration shown in FIG.
　図６は、固有のＪＮＤインデックス値でキャリブレーションを行ってガンマ補正値を予め設定し、輝度の検出値がＤＩＣＯＭカーブでの輝度値と合致するようにバックライトのパワーを調整して階調補正を行う表示装置の構成の一例である。 FIG. 6 shows a calibration by using a unique JND index value to set a gamma correction value in advance, and adjusting the backlight power so that the detected luminance value matches the luminance value in the DICOM curve, thereby correcting the gradation. It is an example of a structure of the display apparatus which performs.
　図６において、表示装置１０１を構成する入力部１１１、ガンマ補正部１１２、基準映像発生部１１３、表示部１１４、バックライト１１５、バックライト駆動部１１６、画面輝度検出部１１７、補正値設定部１１８は、図２における表示装置１を構成する、入力部１１、ガンマ補正部１２、基準映像発生部１３、表示部１４、バックライト１５、バックライト駆動部１６、画面輝度検出部１７、補正値計算部１８と対応している。入力部１１１には、外部機器１０２からの映像信号が入力される。 In FIG. 6, an input unit 111, a gamma correction unit 112, a reference video generation unit 113, a display unit 114, a backlight 115, a backlight driving unit 116, a screen luminance detection unit 117, and a correction value setting unit 118 that constitute the display device 101. 2 includes the input unit 11, the gamma correction unit 12, the reference video generation unit 13, the display unit 14, the backlight 15, the backlight driving unit 16, the screen luminance detection unit 17, and the correction value calculation. Corresponds to part 18. A video signal from the external device 102 is input to the input unit 111.
　図６における表示装置１０１では、補正値設定部１１８は、キャリブレーション時に、固有のＪＮＤインデックス値を設定し、ＤＩＣＯＭカーブに合致するようなガンマ特性を求め、ガンマ補正部１１２に予め設定する。したがって、ガンマ補正部１１２のガンマ特性は、固定値となる。そして、表示動作中に、画面輝度検出部１１７で、固有のＪＮＤインデックス値での表示部１４の輝度値を検出し、バックライト駆動部１１６により、この輝度の検出値がＤＩＣＯＭカーブでの輝度値と合致するように、バックライト１１５のパワーを調整している。したがって、バックライト１１５のパワーが輝度の検出値に追従して変更される。 6, the correction value setting unit 118 sets a unique JND index value at the time of calibration, obtains a gamma characteristic that matches the DICOM curve, and sets it in the gamma correction unit 112 in advance. Therefore, the gamma characteristic of the gamma correction unit 112 is a fixed value. Then, during the display operation, the screen luminance detection unit 117 detects the luminance value of the display unit 14 with the unique JND index value, and the backlight driving unit 116 converts the luminance detection value into the luminance value on the DICOM curve. The power of the backlight 115 is adjusted so as to match. Therefore, the power of the backlight 115 is changed following the detected luminance value.
　これに対して、図２に示した本発明に係る表示装置１は、バックライト１５を最大パワーとなる固定値で駆動する。そして、画面輝度検出部１７は表示部１４の画面の輝度を検出し、補正値計算部１８は画面輝度検出部１７で検出された輝度値から、この輝度値に対応するＪＮＤインデックス値を判定する。そして、補正値計算部１８は、判定されたＪＮＤインデックス値を最大輝度値として設定し、ＤＩＣＯＭカーブに合致するようなガンマ特性を求め、ガンマ補正部１２に設定する。したがって、ガンマ補正部１２の特性が輝度の検出値に追従して変更される。 On the other hand, the display device 1 according to the present invention shown in FIG. 2 drives the backlight 15 at a fixed value that provides the maximum power. The screen luminance detection unit 17 detects the luminance of the screen of the display unit 14, and the correction value calculation unit 18 determines a JND index value corresponding to the luminance value from the luminance value detected by the screen luminance detection unit 17. . Then, the correction value calculation unit 18 sets the determined JND index value as the maximum luminance value, obtains a gamma characteristic that matches the DICOM curve, and sets it in the gamma correction unit 12. Therefore, the characteristic of the gamma correction unit 12 is changed following the detected luminance value.
　図６に示したような表示装置１０１では、高輝度表示を行うためには、キャリブレーションを行う際に最大輝度値として設定する固有値のＪＮＤインデックス値を高くする必要がある。しかしながら、最大輝度値として設定する固有値のＪＮＤインデックス値を高くすると、表示装置の輝度が経時変化により劣化した場合に、ＤＩＣＯＭカーブと合致した階調特性が得られなくなり、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅが悪化してしまう。 In the display device 101 as shown in FIG. 6, in order to perform high luminance display, it is necessary to increase the JND index value of the eigenvalue set as the maximum luminance value when performing calibration. However, if the JND index value of the eigenvalue that is set as the maximum luminance value is increased, the gradation characteristics that match the DICOM curve cannot be obtained when the luminance of the display device deteriorates due to changes over time, and MaxGSDF ErrorRate deteriorates. .
　つまり、経時変化により、表示装置１０１で表示可能な輝度が図７に示すような特性で劣化していくとする。図７において、横軸は使用時間を示し、縦軸はＪＮＤインデックス値で換算した輝度を示す。この例では、表示可能な輝度の劣化を考慮して、キャリブレーションを行う際の最大輝度値を（JND index＝６７０）の固有値に設定して、ＤＩＣＯＭカーブに合致するようなガンマ特性を求め、ガンマ補正部１１２に設定している。 That is, it is assumed that the luminance that can be displayed on the display device 101 deteriorates with the characteristics shown in FIG. In FIG. 7, the horizontal axis indicates the usage time, and the vertical axis indicates the luminance converted with the JND index value. In this example, in consideration of deterioration of displayable luminance, the maximum luminance value at the time of calibration is set to an eigenvalue of (JND index = 670), and a gamma characteristic that matches the DICOM curve is obtained. The gamma correction unit 112 is set.
　図７に示すように、表示部１１４は、最初の使用状態では、ＪＮＤインデックス値が（JND index＝８００）に相当する輝度値で表示可能である。しかし、表示可能な輝度値は時間と共に劣化していき、使用時間Ｔ１では、表示可能な輝度値がＪＮＤインデックス値で（JND index＝６７０）に相当する輝度値以下まで劣化している。 As shown in FIG. 7, the display unit 114 can display a luminance value corresponding to the JND index value (JND index = 800) in the first use state. However, the displayable luminance value deteriorates with time, and at the usage time T1, the displayable luminance value is deteriorated to a luminance value equal to or less than the luminance value corresponding to the JND index value (JND index = 670).
　このような例では、使用時間Ｔ１までは、表示部１１４で表示可能な輝度は、最大値として設定したＪＮＤインデックスの固有値（JND index＝６７０）に対応する輝度値以上である。したがって、バックライト１１５を調整することで、表示部１１４の輝度の検出値を、最大値として設定したＪＮＤインデックスの固有値（JND index＝６７０）に相当する輝度値と合致させることができる。これにより、ＤＩＣＯＭカーブと合致した階調特性が得られる。 In such an example, until the usage time T1, the luminance that can be displayed on the display unit 114 is equal to or higher than the luminance value corresponding to the unique value of the JND index (JND index = 670) set as the maximum value. Therefore, by adjusting the backlight 115, the detected value of the luminance of the display unit 114 can be matched with the luminance value corresponding to the eigenvalue of the JND index (JND index = 670) set as the maximum value. As a result, gradation characteristics that match the DICOM curve are obtained.
　ところが、使用時間Ｔ１を超えると、表示部１１４で表示可能な輝度値が、最大輝度値として設定したＪＮＤインデックスの固有値（JND index＝６７０）に相当する輝度値以下になる。このため、使用時間Ｔ１を超えた後では、バックライト１１５を調整しても、表示部１１４の輝度の検出値を、最大値として設定したＪＮＤインデックスの固有値（JND index＝６７０）に相当する輝度値と合致させることができない。このため、ＤＩＣＯＭカーブと合致した階調特性が得られなくなり、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅが悪化する。 However, when the usage time T1 is exceeded, the luminance value that can be displayed on the display unit 114 becomes equal to or less than the luminance value corresponding to the unique value (JND index = 670) of the JND index set as the maximum luminance value. For this reason, after the usage time T1 is exceeded, even if the backlight 115 is adjusted, the luminance value corresponding to the eigenvalue (JND index = 670) of the JND index set as the maximum value of the luminance detection value of the display unit 114 Cannot match the value. For this reason, gradation characteristics that match the DICOM curve cannot be obtained, and MaxGSDF ErrorRate is deteriorated.
　このような制限から、図６に示したような表示装置１０１では、キャリブレーションを行う際に最大値として設定するＪＮＤインデックスの固有値を高くできず、高輝度表示と高精度表示との両立が難しい。例えば、上述のような劣化特性で、最大値として設定するＪＮＤインデックスの固有値を（JND index＝８００）とすると、初期には高輝度表示が可能となるが、輝度劣化により、例えば約３０，０００時間後には、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅが１０％を超えてしまう。 Due to such limitations, the display device 101 as shown in FIG. 6 cannot increase the eigenvalue of the JND index set as the maximum value when performing calibration, and it is difficult to achieve both high luminance display and high accuracy display. . For example, if the characteristic value of the JND index set as the maximum value in the deterioration characteristics as described above is (JND 劣化 index = 800), high luminance display is possible at the beginning, but due to the luminance deterioration, for example, about 30,000. After time, MaxGSDF ErrorRate will exceed 10%.
　なお、表示装置の経時変化により表示装置１０１の輝度が低下した場合には、図７に示すように、設定するＪＮＤインデックス値を例えば（JND index＝５００）に下げて、再キャリブレーションを行い、ガンマ特性を設定し直すことが考えられる。しかしながら、輝度の劣化に応じて、再キャリブレーションを繰り返すのでは、管理コストが上昇してしまう。 When the luminance of the display device 101 decreases due to the change of the display device with time, as shown in FIG. 7, the JND index value to be set is lowered to, for example, (JND index = 500), and recalibration is performed. It may be possible to reset the gamma characteristic. However, if recalibration is repeated according to the deterioration of luminance, the management cost increases.
　これに対して、本発明の実施形態に係る表示装置１は、バックライト１５が最大パワーとなる最大輝度まで表示することができ、高輝度表示が行える。また、本発明の実施形態に係る表示装置１は、表示動作中は、所定の周期で画面の輝度を検出し、検出した輝度に対応するＪＮＤインデックス値を判定してガンマ特性を算出しているため、経時変化により表示装置１の特性が変化しても、この変化特性に応じて、ガンマ補正部１２のガンマ特性が変更される。このため、経時変化により、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅが大きく劣化することがない。 On the other hand, the display device 1 according to the embodiment of the present invention can display up to the maximum luminance at which the backlight 15 has the maximum power, and can perform high luminance display. In addition, during the display operation, the display device 1 according to the embodiment of the present invention detects the luminance of the screen at a predetermined cycle, determines the JND index value corresponding to the detected luminance, and calculates the gamma characteristic. Therefore, even if the characteristics of the display device 1 change due to changes over time, the gamma characteristics of the gamma correction unit 12 are changed according to the change characteristics. For this reason, MaxGSDF ErrorRate does not deteriorate significantly due to a change with time.
　つまり、本発明の実施形態に係る表示装置１において、経時変化により、表示部１４で表示可能な輝度が図８に示すような特性で劣化していくとする。図８に示すように、表示部１４は、最初の使用状態では、ＪＮＤインデックス値が（JND index＝８００）に相当する輝度値で表示可能である。しかし、表示可能な輝度値は時間と共に劣化していき、使用時間Ｔ１では、表示可能な輝度値はＪＮＤインデックス値で（JND index＝６７０）に相当する輝度値以下まで劣化している。 That is, in the display device 1 according to the embodiment of the present invention, it is assumed that the luminance that can be displayed on the display unit 14 deteriorates with the characteristics shown in FIG. As shown in FIG. 8, the display unit 14 can display a luminance value corresponding to the JND index value (JNDJindex = 800) in the first use state. However, the displayable luminance value deteriorates with time, and at the usage time T1, the displayable luminance value is deteriorated to a luminance value corresponding to (JND index = 670) or less as the JND index value.
　最初の状態では、バックライト１５を最大パワーで駆動したときの輝度の検出値は、（JND index＝８００）に相当する輝度値である。このため、補正値計算部１８は、最大輝度値を（JND index＝８００）に設定して、ガンマ補正部１２のガンマ特性を設定する。使用時間Ｔ１に達すると、バックライト１５を最大パワーで駆動したときの輝度の検出値は、（JND index＝６７０）に相当する輝度値となる。このため、補正値計算部１８は、最大輝度値を（JND index＝６７０）に設定して、ガンマ補正部１２のガンマ特性を設定する。 In the initial state, the detected value of luminance when the backlight 15 is driven at the maximum power is a luminance value corresponding to (JND index = 800). For this reason, the correction value calculation unit 18 sets the maximum luminance value to (JND ＝ index = 800) and sets the gamma characteristic of the gamma correction unit 12. When the usage time T1 is reached, the detected luminance value when the backlight 15 is driven at the maximum power becomes a luminance value corresponding to (JND index = 670). Therefore, the correction value calculation unit 18 sets the maximum luminance value to (JNDJindex = 670) and sets the gamma characteristic of the gamma correction unit 12.
　このように、本発明の実施形態に係る表示装置１では、ガンマ補正値を算出する際の最大輝度値は、常に、バックライト１５が最大パワーのときの輝度値に相当するＪＮＤインデックス値となる。このため、本実施形態に係る表示装置１では、高輝度表示が可能になる。 Thus, in the display device 1 according to the embodiment of the present invention, the maximum luminance value when calculating the gamma correction value is always a JND index value corresponding to the luminance value when the backlight 15 has the maximum power. . For this reason, the display device 1 according to the present embodiment enables high-luminance display.
　すなわち、本実施形態に係る表示装置１では、最初の状態で、最大輝度値を（JND index＝８００）に設定でき、その後も、経時変化による表示可能な輝度の劣化特性に沿って、最大輝度値を設定できる。これに対して、図６に示したような表示装置１０１では、最初の状態で設定できる最大輝度値は、経時変化による表示可能な輝度の劣化を考慮して、（JND index＝６７０）となる。 That is, in the display device 1 according to the present embodiment, the maximum luminance value can be set to (JND index = 800) in the initial state, and thereafter, the maximum luminance value can be set in accordance with the luminance degradation characteristics that can be displayed over time. You can set the value. On the other hand, in the display device 101 as shown in FIG. 6, the maximum luminance value that can be set in the initial state is (JND index = 670) in consideration of the degradation of displayable luminance due to the change with time. .
　また、本実施形態に係る表示装置１では、ガンマ補正部１２のガンマ特性が表示部１４の輝度の検出値に追従して更新される。このため、経時変化により、表示部１４の輝度特性が低下しても、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅは悪化せず、高精度の表示が維持できる。また、本実施形態に係る表示装置１では、ガンマ補正部１２のガンマ特性が輝度低下に応じて更新されるので、再キャリブレーションは不要である。 In the display device 1 according to the present embodiment, the gamma characteristic of the gamma correction unit 12 is updated following the detected luminance value of the display unit 14. For this reason, even if the luminance characteristics of the display unit 14 deteriorate due to a change over time, the MaxGSDF ErrorRate does not deteriorate and high-precision display can be maintained. Further, in the display device 1 according to the present embodiment, since the gamma characteristic of the gamma correction unit 12 is updated according to the decrease in luminance, recalibration is unnecessary.
　これに対して、図６に示したような表示装置１０１では、最大輝度値として設定した例えば（JND index＝６７０）より、表示装置１０１で表示可能な輝度が劣化すると、ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅが著しく悪化する。ＭａｘＧＳＤＦ　ＥｒｒｏｒＲａｔｅの悪化を防ぐには、再キャリブレーションを繰り返す必要がある。 On the other hand, in the display device 101 as shown in FIG. 6, MaxGSDF ErrorRate is significantly deteriorated when the luminance that can be displayed on the display device 101 is deteriorated from, for example, (JND index = 670) set as the maximum luminance value. . In order to prevent the deterioration of MaxGSDF ErrorRate, it is necessary to repeat recalibration.
　以上説明したように、本実施形態に係る表示装置１では、高輝度表示と高精度表示との両立が可能である。 As described above, the display device 1 according to the present embodiment can achieve both high luminance display and high accuracy display.
　なお、上述の例では、バックライト１５を最大パワーの固定値に設定しているが、バックライト１５に設定する固定値は、最大パワーでなくても良く、一定値又は温度制限値などでも良い。 In the above-described example, the backlight 15 is set to a fixed value of the maximum power. However, the fixed value set to the backlight 15 may not be the maximum power, and may be a constant value or a temperature limit value. .
　また、上述の例では、画面輝度検出部１７で、表示部１４の輝度を検出しているが、バックライト１５の輝度を検出しても良い。なお、バックライト１５の輝度を検出する場合は、白色画面は不要である。 In the above-described example, the screen brightness detection unit 17 detects the brightness of the display unit 14. However, the brightness of the backlight 15 may be detected. In addition, when detecting the brightness | luminance of the backlight 15, a white screen is unnecessary.
　なお、上述した実施形態である表示装置の一部、例えば補正値計算部１８の機能をコンピュータで実現するようにしてもよい。この場合、その制御機能を実現するためのプログラムをコンピュータ読み取り可能な記録媒体に記録し、この記録媒体に記録されたプログラムをコンピュータシステムに読み込ませて、このコンピュータシステムが実行することによって実現してもよい。なお、このコンピュータシステムとは、オペレーティング・システム（Ｏｐｅｒａｔｉｎｇ　Ｓｙｓｔｅｍ；ＯＳ）や周辺装置のハードウェアを含むものである。また、コンピュータ読み取り可能な記録媒体とは、フレキシブルディスク、光磁気ディスク、光ディスク、メモリカード等の可搬型記録媒体、コンピュータシステムに備えられる磁気ハードディスクやソリッドステートドライブ等の記憶装置のことをいう。さらに、コンピュータ読み取り可能な記録媒体とは、インターネット等のコンピュータネットワーク、および電話回線や携帯電話網を介してプログラムを送信する場合の通信回線のように、短時間の間、動的にプログラムを保持するもの、さらには、その場合のサーバ装置やクライアントとなるコンピュータシステム内部の揮発性メモリのように、一定時間プログラムを保持するものを含んでもよい。また上記のプログラムは、前述した機能の一部を実現するためのものであってもよく、さらに、前述した機能をコンピュータシステムにすでに記録されているプログラムとの組み合わせにより実現するものであってもよい。 In addition, you may make it implement | achieve the function of a part of display apparatus which is embodiment mentioned above, for example, the correction value calculation part 18, with a computer. In this case, a program for realizing the control function is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed by the computer system. Also good. This computer system includes an operating system (OS) and hardware of peripheral devices. The computer-readable recording medium is a portable recording medium such as a flexible disk, a magneto-optical disk, an optical disk, or a memory card, and a storage device such as a magnetic hard disk or a solid state drive provided in the computer system. Furthermore, a computer-readable recording medium holds a program dynamically for a short time, such as a computer network such as the Internet, and a communication line when transmitting a program via a telephone line or a cellular phone network. In addition, a server that holds a program for a certain period of time, such as a volatile memory inside a computer system serving as a server device or a client in that case, may be included. Further, the above program may be for realizing a part of the above-described functions, and further, may be realized by combining the above-described functions with a program already recorded in the computer system. Good.
　以上、本発明の実施の形態について図面を参照して詳述したが、具体的な構成はその実施形態に限られるものではなく、本発明の要旨を逸脱しない範囲の設計等も含まれる。 The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to the embodiment, and includes design and the like within the scope not departing from the gist of the present invention.
　１１　　入力部
　１２　　ガンマ補正部
　１３　　基準映像発生部
　１４　　表示部
　１５　　バックライト
　１６　　バックライト駆動部
　１７　　画面輝度検出部
　１８　　補正値計算部
　５０１　　表示部
　５０２　　光照射部
　５０３　　駆動部
　５０４　　輝度検出部
　５０５　　階調補正部
　５０６　　補正値算出部 DESCRIPTION OF SYMBOLS 11 Input part 12 Gamma correction part 13 Reference | standard image generation part 14 Display part 15 Backlight 16 Backlight drive part 17 Screen brightness | luminance detection part 18 Correction value calculation part 501 Display part 502 Light irradiation part 503 Drive part 504 Brightness detection part 505 Gradation Correction unit 506 Correction value calculation unit

Claims (7)

  1. 　画像を表示する表示部と、
    　前記表示部に対するバックライト光を照射する光照射部と、
    　前記光照射部を固定値で駆動する駆動部と、
    　前記表示部の輝度に対応する輝度値を検出する画面輝度検出部と、
    　入力映像信号の階調特性を補正する階調補正部と、
    　所定の周期で前記画面輝度検出部で検出された輝度値に基づいて階調補正特性を算出し、前記階調補正部に設定する補正値算出部と、
    　を具備することを特徴とする表示装置。     A display for displaying an image;
    A light irradiating unit for irradiating backlight light to the display unit;
    A drive unit for driving the light irradiation unit with a fixed value;
    A screen luminance detection unit for detecting a luminance value corresponding to the luminance of the display unit;
    A tone correction unit for correcting the tone characteristics of the input video signal;
    A correction value calculation unit configured to calculate a gradation correction characteristic based on a luminance value detected by the screen luminance detection unit at a predetermined period, and to set the gradation correction unit;
    A display device comprising:
  2. 　前記駆動部は、前記表示部に対する光が最大パワーとなる固定値で前記光照射部を駆動する
    　ことを特徴とする請求項１に記載の表示装置。     The display device according to claim 1, wherein the driving unit drives the light irradiation unit with a fixed value at which light with respect to the display unit has a maximum power.
  3. 　前記補正値算出部は、ＤＩＣＯＭ階調特性に合致する階調補正特性を前記階調補正部に設定する
    　ことを特徴とする請求項１または２に記載の表示装置。     The display device according to claim 1, wherein the correction value calculation unit sets a gradation correction characteristic that matches a DICOM gradation characteristic in the gradation correction unit.
  4. 　前記補正値算出部は、前記画面輝度検出部で検出された輝度値に対応するＪＮＤインデックス値を判定し、前記判定されたＪＮＤインデックス値に基づいて、ＤＩＣＯＭカーブ階調特性に合致する階調特性を前記階調補正部に設定する
    　ことを特徴とする請求項３に記載の表示装置。     The correction value calculation unit determines a JND index value corresponding to the luminance value detected by the screen luminance detection unit, and based on the determined JND index value, a gradation characteristic that matches the DICOM curve gradation characteristic The display device according to claim 3, wherein: is set in the gradation correction unit.
  5. 　表示部の光源を固定値で駆動したときの前記表示部の輝度に対応する輝度値を検出する画面輝度検出部と、
    　入力映像信号の階調特性を補正する階調補正部と、
    　所定の周期で前記輝度値に基づいて階調補正特性を算出し、前記階調補正部に設定する補正値算出部と、
    　を具備することを特徴とする階調補正装置。     A screen luminance detection unit for detecting a luminance value corresponding to the luminance of the display unit when the light source of the display unit is driven at a fixed value;
    A tone correction unit for correcting the tone characteristics of the input video signal;
    A correction value calculation unit that calculates a gradation correction characteristic based on the luminance value at a predetermined period and sets the gradation correction unit;
    A gradation correction apparatus comprising:
  6. 　表示部の光源を固定値で駆動し、
    　前記表示部に対する光を固定値で駆動したときの前記表示部の輝度に対応する輝度値を検出し、
    　所定の周期で前記輝度値に基づいて階調補正特性を算出して、入力映像信号の階調補正を行う
    　ことを特徴とする階調補正方法。     Drive the light source of the display unit at a fixed value,
    Detecting a luminance value corresponding to the luminance of the display unit when the light for the display unit is driven at a fixed value;
    A gradation correction method, wherein gradation correction characteristics are calculated based on the luminance value at a predetermined period to perform gradation correction of an input video signal.
  7. 　表示部の光源を固定値で駆動するステップと、
    　前記表示部に対する光を固定値で駆動したときの前記表示部の輝度に対応する輝度値を検出するステップと、
    　所定の周期で前記輝度値に基づいて階調補正特性を算出するステップと、
    　を含むことを特徴とするコンピュータにより実行可能な階調補正プログラム。     Driving the light source of the display unit at a fixed value;
    Detecting a luminance value corresponding to the luminance of the display unit when the light for the display unit is driven with a fixed value;
    Calculating a gradation correction characteristic based on the luminance value at a predetermined period;
    A gradation correction program that can be executed by a computer.
PCT/JP2013/060309 2013-04-04 2013-04-04 Display device, greyscale correction device, greyscale correction method, and greyscale correction program WO2014162555A1 (en)

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