WO2018055657A1 - Image display device and image display method - Google Patents

Image display device and image display method Download PDF

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Publication number
WO2018055657A1
WO2018055657A1 PCT/JP2016/077620 JP2016077620W WO2018055657A1 WO 2018055657 A1 WO2018055657 A1 WO 2018055657A1 JP 2016077620 W JP2016077620 W JP 2016077620W WO 2018055657 A1 WO2018055657 A1 WO 2018055657A1
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WIPO (PCT)
Prior art keywords
black
screen
image
display
luminance
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PCT/JP2016/077620
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French (fr)
Japanese (ja)
Inventor
勝之 松井
Original Assignee
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/JP2016/077620 priority Critical patent/WO2018055657A1/en
Priority to JP2018540242A priority patent/JP6645668B2/en
Publication of WO2018055657A1 publication Critical patent/WO2018055657A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • 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
    • 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

Definitions

  • the present invention relates to an image display device such as a liquid crystal monitor and an image display method.
  • image display devices In business such as medical use or graphic design, it is used for diagnosis and expression of colors, so that it is necessary to reproduce color numerically accurately for an image display device (display). For this reason, image display devices are required to be accurate in luminance and chromaticity of an image displayed on the display screen and uniform in the display screen. Further, in recent years, image display apparatuses have been integrated with display of medical image diagnosis (X-ray images) and office electronic medical records that have been operated on different apparatuses, for example, as the display screen has been enlarged. Display using PinP (picture in picture) / PbyP (picture by picture) is required.
  • FIG. 7 is a three-dimensional graph showing an example of display unevenness in the display screen of the image display apparatus. Generally, the state of display unevenness in the display screen differs depending on the individual image display device.
  • FIG. 7 shows the screen brightness value [cd of the z axis in the pixel set by the coordinate values of the x axis corresponding to the horizontal position and the y axis corresponding to the vertical position on the display screen of the image display device. / m 2 ]. That is, the display unevenness (nonuniformity of the screen luminance value) on the display screen of the image display device when each pixel displays an image of the same gradation.
  • the image offset circuit 201 sets the black level of the screen image input via the image input unit 202 in the image quality setting storage unit 203 in advance.
  • the offset is adjusted according to the black level (black level correction data).
  • the image offset circuit 204 also displays the black level of the screen image input via the image input unit 205 (the black level set independently of the black label input to the image offset circuit 201), and the image quality setting storage unit 203. Adjust the offset according to the black level set to.
  • the image composition circuit 206 synthesizes the screen images adjusted by the offsets output from the image offset circuits 201 and 204, and generates a display screen image.
  • the black unevenness correction circuit 207 performs black unevenness correction of the display screen image based on the black unevenness correction data which is the unevenness correction setting set in the image quality setting storage unit 203 and outputs the black image to the image display unit 208.
  • the black unevenness correction circuit 207 performs black unevenness correction by unevenness correction that makes the display unevenness of the image display unit 208 uniform display on the display screen.
  • the image display unit 208 is a liquid crystal panel, and displays the display screen image supplied from the black unevenness correction circuit 207 on the display screen.
  • FIG. 8 is a conceptual diagram of the image display device of Patent Document 1.
  • the image display device disclosed in Patent Document 1 corrects unevenness of black unevenness (display unevenness) in the display screen, which is different from the setting of the black level, and a combination of these two independent black level settings.
  • the image quality on each screen displayed on the display screen of the image display unit 208 is determined.
  • the black unevenness correction circuit 207 performs unevenness correction of the display screen, whereby the black level of the entire display screen of the image display unit 208 is increased, and a desired contrast characteristic for each screen displayed on the display screen is obtained. It becomes impossible.
  • an object of the present invention is to provide an image display device and an image display method capable of displaying an appropriate image for each of a plurality of screens displayed on a display screen.
  • the present invention is an image display apparatus that corrects and displays black unevenness of a plurality of screens displayed on a display screen of a liquid crystal panel, and each of the screens has an offset amount based on a black level set for each screen.
  • An image display comprising: an image offset unit that adjusts the black level; and a black unevenness correcting unit that performs unevenness correction on the entire display screen based on the black level and a white level set for each screen.
  • the present invention is an image display that corrects and displays black unevenness of each of a plurality of screens displayed on a display screen of a liquid crystal panel, and an image offset unit is an offset amount based on a black level set for each screen Therefore, the black offset for adjusting the black level of each of the screens, and the black unevenness correction unit performs unevenness correction on the entire display screen based on the black level and the white level set for each screen. And a correction process.
  • FIG. 4 is a flowchart illustrating a processing example of displaying a display screen image on a liquid crystal panel 21 performed by the image display device 1. It is a three-dimensional graph which shows an example of the display nonuniformity in the display screen of an image display apparatus.
  • 1 is a conceptual diagram of an image display device of Patent Document 1.
  • FIG. 1 is a diagram illustrating a configuration example of an image display device 1 according to an embodiment of the present invention.
  • the image display device 1 includes a black luminance calculation unit 11, an offset amount calculation unit 12, a minimum black luminance selection unit 13, a maximum luminance selection unit 14, a black unevenness correction amount calculation unit 15, and an image input unit 16.
  • the black level and the white level are input by the user as display screen settings for each screen (for example, window display) displayed on the display screen of the liquid crystal panel 21. That is, the user sets each desired white level and black level for the image display device 1 for each screen on the display screen of the liquid crystal panel 21.
  • the unit and range of the set value are arbitrary, but in this embodiment, the unit and range of each of the white level and the black level are 0 to 100%.
  • the white level corresponds to the brightest luminance of the image displayed on a predetermined screen (the luminance when the maximum gradation is displayed).
  • the black level corresponds to the darkest brightness of the image displayed on the predetermined screen (the brightness when the minimum gradation is displayed).
  • the white level is controlled by varying the maximum output level of the backlight and the image signal (the maximum light transmittance in the pixels of the liquid crystal panel 21).
  • the black level varies the minimum level of the image signal (the minimum light transmittance in the pixels of the liquid crystal panel 21).
  • the operation of changing and controlling the backlight and the image signal is the same as that of a general liquid crystal panel.
  • the display screen is displayed using, for example, PinP (picture in picture), PbyP (picture by picture), and the like. That is, when displaying as PinP, a 2nd screen is displayed in the one part area
  • the display area is divided into two, the first screen is displayed in one area, and the second screen is displayed in the other screen.
  • two screens the first screen and the second screen
  • a plurality of screens such as three screens (the first screen, the second screen, and the third screen) are displayed. It may be.
  • the black luminance calculation unit 11 calculates black luminance that is an absolute value of the black level in each screen (actual luminance when displayed on each screen) from the black level and white level for each screen set by the user. .
  • black luminance it is desirable to calculate accurate black screen luminance [cd / m 2 ] on the display screen.
  • the result of simply multiplying each of the black level and the white level is obtained as the black luminance. That is, the black luminance corresponds to the luminance when an image with the minimum gradation is displayed on the display screen.
  • the black level of the screen P1 is 10% and the white level is 30%.
  • the black level indicates the light transmittance in the pixels of the liquid crystal panel 20.
  • the white level is a maximum luminance value and indicates a ratio with respect to the maximum illuminance of a backlight (not shown).
  • the liquid crystal panel 20 displays an image by modulating the light emitted from the backlight based on the video signal.
  • the black level is a relative value with respect to the white level. For this reason, unlike the white level, the black level itself cannot clarify the size between screens.
  • the above-described black luminance is calculated and the relative evaluation of the black level between the screens is performed.
  • the minimum black luminance selection unit 13 selects the smallest black luminance (minimum black luminance) among the black luminances in the respective screens obtained by the black luminance calculation unit 11. In addition, the minimum black luminance selection unit 13 outputs the selected minimum black luminance to the black unevenness correction amount calculation unit 15. Here, in the present embodiment, the minimum black luminance selection unit 13 selects the black luminance 0.03 of the screen P1.
  • the maximum brightness selection unit 14 selects the maximum brightness value (white brightness), that is, the maximum white level (maximum white level) from each white level of the screen. Further, the minimum black luminance selection unit 13 outputs the selected maximum white level to the black unevenness correction amount calculation unit 15. In the present embodiment, the maximum luminance selection unit 14 selects the white level 1.0 of the screen P2.
  • the image input unit 16 inputs each screen display image of the screen displayed on the image display surface of the liquid crystal panel 21 from an external device.
  • the offset amount calculation unit 12 calculates an image offset correction amount based on each of the black luminance, the minimum black luminance, and the maximum white level of the screen.
  • the offset amount calculation unit 12 subtracts the minimum black luminance from each of the black luminances of the screen, and obtains the differential luminance of each screen as the subtraction result. Then, the offset amount calculation unit 12 divides each difference luminance of the screen by the maximum white level to obtain an image offset correction amount for each screen. Further, the offset amount calculation unit 12 outputs the obtained image offset correction amount to the image offset unit 17.
  • the image offset unit 17 increases the black level of each screen display image on the screen based on the image offset correction amount supplied from the offset amount calculation unit 12. That is, the image offset unit 17 performs a process of increasing the gradation of each pixel of the screen display image by the amount of the image offset, and outputs a screen display image having the corrected gradation.
  • the image offset unit 17 since the image offset correction amount for the screen display image of the screen P1 is 0, the image offset unit 17 does not perform correction by the offset for the screen display image of the screen P1.
  • the image offset correction amount with respect to the screen display image of the screen P2 is 0.02, the image offset unit 17 performs a correction to increase each gradation of the screen display image of the screen P2 by the image offset correction amount 0.02. I do.
  • the image composition unit 18 synthesizes each of the screen display image of the screen P1 and the screen display image of the screen P2 on which the offset correction has been performed by the image offset unit 17 as a display screen image to be displayed on the display screen of the liquid crystal panel 21. Then, the image composition unit 18 outputs the synthesized display screen image to the black unevenness correction unit 19.
  • the black unevenness correction amount calculation unit 15 calculates a target contrast ratio from the maximum white level and the minimum black luminance.
  • the black unevenness correction amount calculation unit 15 since the maximum white level is white level 1 and the minimum black luminance is black luminance 0.03, the black unevenness correction amount calculation unit 15 has a target contrast ratio of 100: 3 ( ⁇ 33: 1). Is calculated as This method of calculating the contrast ratio is a simple calculation, and a procedure that can calculate an accurate contrast ratio such as multiplication by a coefficient may be used.
  • the black unevenness correction amount calculation unit 15 compares the target contrast ratio with the adjustment contrast ratio that is the contrast ratio at the time of display unevenness adjustment, and obtains the black unevenness correction amount so that the target contrast ratio is obtained. In the storage unit 20, the adjustment contrast ratio is written and stored in advance. Hereinafter, this adjustment contrast ratio will be described.
  • unevenness correction display unevenness
  • the unevenness correction data generally includes color (for example, each of R (red), G (green), and B (blue)) and gradation (gradation 255, 192, 128, 64, 0) is stored as an independent look-up table corresponding to each position on the display screen (for example, a predetermined 20 horizontal pixels and 11 vertical pixels in the display screen pixel arrangement). It is written and stored in the unit 20.
  • correction values are not all set with respect to the pixel position and pixel gradation on the display screen, but to suppress an increase in the storage capacity of the storage unit 20, a predetermined representative gradation or It is set for pixels at positions scattered at predetermined intervals.
  • the unevenness correction of the liquid crystal panel is performed using unevenness correction data. Note that black unevenness correction corresponds to gradation 0 unevenness correction.
  • the correction value is obtained by, for example, linear interpolation of the correction values of the two adjacent pixels that have the correction value. .
  • the correction value is set by linear interpolation of the correction values of the two closest gradations where the correction value exists. Will be asked.
  • the display unevenness adjustment on the display screen is performed by obtaining a correction value for reducing the display unevenness based on a two-dimensional luminance distribution (display unevenness distribution) acquired by an image sensor such as a CCD (charge coupled device).
  • the adjustment contrast ratio is obtained as the contrast ratio between the black level and the white level of the pixel at the center position of the display screen when the above-described display unevenness is corrected, and is stored in the storage unit 20 in advance. Has been written. Further, the contrast ratio when the black unevenness correction of the pixel at the center position of the display screen is not performed is written and stored in the storage unit 20 as an uncorrected contrast ratio.
  • display unevenness black unevenness correction
  • the brightness of the white level decreases and the brightness of the black level increases. For this reason, the contrast ratio at the time of adjustment is lower than the uncorrected contrast ratio. For example, even when the uncorrected contrast ratio is 1000: 1, when the display unevenness is corrected, the contrast ratio during adjustment is reduced to 300: 1.
  • the black unevenness correction amount calculation unit 15 refers to the adjustment contrast ratio stored in the storage unit 20 and displays the target contrast ratio so that the target contrast ratio can be realized using the display unevenness correction value in the lookup table. A black unevenness correction amount of each pixel of the screen image is calculated.
  • the display unevenness correction value in the lookup table stored in the storage unit 20 corresponds to the adjustment contrast ratio. For this reason, when the correction value of the lookup table is used as it is, the target contrast ratio desired by the user cannot be obtained.
  • the black unevenness correction amount calculation unit 15 performs the following processing so as to obtain the target contrast ratio. First, the black unevenness correction amount calculation unit 15 reads the adjustment contrast ratio and the uncorrected contrast ratio from the storage unit 20. Further, the black unevenness correction amount calculation unit 15 looks up the unevenness correction amount for the gradation of each pixel corresponding to the gradation of each pixel and the position of the liquid crystal panel 21 in the display screen image. Calculate with reference to the table. As described above, the black unevenness correction amount calculation unit 15 is the representative position where the target pixel exists in the lookup table and is a representative gradation, and the unevenness correction amount corresponding to that position and gradation. Is a correction value of the pixel.
  • the black unevenness correction amount calculation unit 15 uses linear interpolation or the like from each of the representative position and the representative gradation. calculate.
  • the black unevenness correction amount calculation unit 15 compares the target contrast ratio with each of the adjustment contrast ratio and the uncorrected contrast ratio. Then, if the target contrast ratio is equal to or smaller than the adjustment contrast ratio, the black unevenness correction amount calculation unit 15 uses the gradation value (unevenness correction amount) obtained as described above as the black unevenness correction amount, and the black unevenness correction unit 19. Output for. On the other hand, when the target contrast ratio exceeds the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 sets the black unevenness correction amount to “0” and outputs it to the black unevenness correction unit 19.
  • the black unevenness correction amount calculation unit 15 performs non-correction on the subtraction result obtained by subtracting the adjustment contrast ratio from the target contrast ratio when the target contrast ratio exceeds the adjustment contrast ratio and less than the non-correction contrast ratio. Division is performed by a subtraction result obtained by subtracting the contrast ratio from the contrast ratio at the time of adjustment, and a numerical value obtained by subtracting the division result from 1 is used as the adjustment amount. Then, the black unevenness correction amount calculation unit 15 multiplies the obtained unevenness correction amount by the adjustment amount and outputs the multiplication result to the black unevenness correction unit 19 as a black unevenness correction amount.
  • the black luminance obtained from the white level and the black level set on each screen is set to a relative black level with respect to the maximum white level in correspondence with the comparison between the target contrast ratio and the adjustment contrast ratio. It is converted again.
  • the black unevenness correction is correction of display unevenness of the display screen image.
  • the white level (maximum white level) is set as the maximum luminance value (reference value), and the relative value to the white level is used to correct the display unevenness. This is performed to calculate the black unevenness correction amount to be used.
  • the absolute luminance in a liquid crystal display such as the liquid crystal panel 21 is determined by controlling the irradiation light of the backlight. For this reason, it is necessary to obtain image correction values such as the offset amount and the black unevenness correction amount as relative values with respect to the white level.
  • FIG. 2 is a diagram illustrating an example of display unevenness when black unevenness correction is performed when the target contrast is 100: 1.
  • FIG. 3 is a diagram illustrating an example of display unevenness when black unevenness correction is performed when the target contrast is 30: 1 in the present embodiment.
  • FIG. 4 is a diagram illustrating an example of display unevenness when black unevenness correction is performed when the target contrast is 10: 1 in the present embodiment.
  • the display unevenness in the display screen varies depending on the individual display panel.
  • the x-axis indicates the pixel position in the horizontal direction (for example, the longitudinal direction or the horizontal direction) of the display screen of the liquid crystal panel 21.
  • the y-axis indicates the pixel position in the vertical direction (for example, the short direction or the vertical direction) of the display screen of the liquid crystal panel 21.
  • the z-axis indicates the screen brightness [cd / m 2 ] at the pixel position on the display screen indicated by the x-coordinate on the x-axis and the y-coordinate on the y-axis.
  • This screen brightness corresponds to the black unevenness correction amount.
  • FIG. 2 shows a state where black unevenness correction is not applied or hardly applied.
  • FIG. 3 shows a state in which black unevenness correction is performed so that the minimum luminance of the display screen is about 0.4 [cd / m 2 ].
  • FIG. 4 shows a state in which the black unevenness correction is performed so that the minimum luminance of the display screen is about 0.6 [cd / m 2 ].
  • the black unevenness correction unit 19 corrects the gradation of each pixel of the display screen image with a gradation value corresponding to the black unevenness correction amount obtained by the black unevenness correction amount calculation unit 15. Then, the black unevenness correction unit 19 outputs a display screen image in which the gradation of each pixel is corrected to the liquid crystal panel 21.
  • the liquid crystal panel 21 displays the display screen image supplied from the black unevenness correction unit 19 on the display screen.
  • the black level is divided and corrected, that is, corrected in two stages, so that the image quality setting for each screen and the display unevenness on the display screen
  • Each of the above suppression (unevenness correction) can be performed at the same time.
  • independent black levels can be set for each of a plurality of screens, and black unevenness correction for the entire display screen can be performed.
  • the screen display image corresponding to the set image quality can be appropriately displayed on the screen.
  • FIG. 5 is a diagram for explaining the concept of the embodiment of the present invention.
  • an image display device 100 according to the embodiment of the present invention is an image display device that corrects and displays black unevenness of each of a plurality of screens displayed on the display screen of the liquid crystal panel.
  • a black unevenness correction unit 19 and a liquid crystal panel 21 are provided.
  • the image offset unit adjusts the luminance of the black level of each screen by an offset amount based on the black level set for each screen displayed on the display screen of the liquid crystal panel 21.
  • the black unevenness correction unit 19 performs unevenness correction on the entire display screen image obtained by synthesizing the screen displayed on the display screen of the liquid crystal panel 21 based on the black level and the white level set for each screen.
  • the display screen image is output.
  • FIG. 6 is a flowchart illustrating a processing example of displaying a display screen image on the liquid crystal panel 21 performed by the image display device 1.
  • Step S1 The image input unit 16 inputs a screen display image of each screen displayed on the display screen of the liquid crystal panel 21 from an external device. Further, the setting values of the black level and the white level for each of the screens are input from the input means (not shown) by the user, and are written and stored in the storage unit 20.
  • Step S2 The black luminance calculation unit 11 reads the black level and the white level of each screen from the storage unit 20, calculates the black luminance of each screen, and writes and stores it in the storage unit 20 corresponding to each screen.
  • Step S3 The minimum black luminance selection unit 13 refers to the storage unit 20, selects and reads out the minimum black luminance from the stored black luminances of the respective screens as the minimum black luminance, and outputs it to the offset amount calculation unit 12.
  • the maximum brightness selection unit 14 refers to the storage unit 20, selects and reads the maximum white level from the stored white levels of each screen as the maximum white level, and outputs it to the offset amount calculation unit 12.
  • the offset amount calculation unit 12 calculates an image offset correction amount (offset amount) from the minimum black luminance and the maximum white level. That is, the offset amount calculation unit 12 calculates the difference luminance of each screen from the black luminance and the minimum black luminance of each screen.
  • the offset amount calculation unit 12 divides each difference luminance of the screen by the maximum white level, and calculates the division result as an image offset correction amount for each screen.
  • the offset amount calculation unit 12 outputs each image image offset correction amount on the screen to the image offset unit 17.
  • Step S4 Based on the supplied image offset correction amount, the image offset unit 17 performs gradation correction in the screen display image of each screen by an offset process that increases the black level of each screen display image on the screen. Then, the image composition unit 18 performs composition of each of the screen display images on which the gradation has been corrected, and generates a display screen image to be displayed on the display screen of the liquid crystal panel 21.
  • Step S6 The black unevenness correction amount calculation unit 15 stores the unevenness correction amount corresponding to the gradation and position of each pixel corresponding to the gradation of each pixel and the position of the liquid crystal panel 21 in the display screen image. Referring to the look-up table, a line interpolation using the correction value of the look-up table is performed.
  • Step S7 Next, the black unevenness correction amount calculation unit 15 divides the maximum white level by the minimum black luminance and sets the division result as the target contrast ratio. Further, the black unevenness correction amount calculation unit 15 reads out the adjustment contrast ratio and the uncorrected contrast ratio from the storage unit 20. Then, the black unevenness correction amount calculation unit 15 compares the target contrast ratio with each of the adjustment contrast ratio and the uncorrected contrast ratio. At this time, if the target contrast ratio is equal to or less than the adjustment contrast ratio, the black unevenness correction amount calculation unit 15 advances the process to step S8. If the target contrast ratio exceeds the adjustment contrast ratio and is less than the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 advances the process to step S9. If the target contrast ratio exceeds the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 advances the process to step S10.
  • Step S8 When the target contrast ratio is equal to or less than the adjustment contrast ratio, the black unevenness correction amount calculation unit 15 outputs the obtained gradation value (unevenness correction amount) to the black unevenness correction unit 19 as a black unevenness correction amount.
  • Step S9 When the target contrast ratio exceeds the adjustment contrast ratio and is less than the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 obtains the subtraction result obtained by subtracting the adjustment contrast ratio from the target contrast ratio. Is divided by the subtraction result subtracted from the contrast ratio at the time of adjustment, and the numerical value obtained by subtracting the division result from 1 is used as the adjustment amount. Then, the black unevenness correction amount calculation unit 15 multiplies the obtained unevenness correction amount by the adjustment amount and outputs the multiplication result to the black unevenness correction unit 19 as a black unevenness correction amount.
  • Step S10 When the target contrast ratio exceeds the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 sets the black unevenness correction amount to “0” and outputs it to the black unevenness correction unit 19.
  • Step S11 The black unevenness correction unit 19 corrects the gradation of each pixel of the display screen image with a gradation value corresponding to the black unevenness correction amount obtained by the black unevenness correction amount calculation unit 15.
  • Step S12 The liquid crystal panel 21 displays the display screen image corrected by the black unevenness correction unit 19 on the display screen.
  • processing for correcting the display unevenness in the liquid crystal panel in the image display device of FIG. 1 may be performed by an external computer system for realizing a control function in the image display device.
  • the “computer system” includes an OS and hardware such as peripheral devices.
  • the above-described image display system is a display using a liquid crystal that requires numerically accurate color reproduction in a display image and is required to be easy to use by a simple operation without imposing a load on the user. Can be applied. In particular, it is suitable for applications that require accurate color reproduction, such as applications for graphic design and printing shops, and medical diagnostic imaging.

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Abstract

The present invention provides an image display device that displays an image after correcting the black unevenness on a plurality of screens displayed on the display screen of a liquid crystal panel, the image display device including: an image offset unit for adjusting the black level for each screen in accordance with the offset amount based on the black level set for each screen; and a black unevenness correction unit for correcting unevenness on the entire display screen in accordance with the black level and a white level set for each screen.

Description

画像表示装置および画像表示方法Image display device and image display method
　本発明は、液晶モニターなどの画像表示装置及び画像表示方法に関する。 The present invention relates to an image display device such as a liquid crystal monitor and an image display method.
　医用あるいはグラフィックデザインなどといった業務においては、診断や色彩の表現に使用されるため、画像表示装置（ディスプレイ）に対して数値的に正確な色再現が必要である。このため、画像表示装置には、表示画面に表示される画像の輝度や色度の正確さ、及び表示画面内における輝度均一性が求められている。
　さらに、近年において、画像表示装置は、表示画面の大画面化に伴い、例えば、異なる装置で運用していた医用における画像診断（Ｘ線画像）と、事務用の電子カルテとの表示の統合（ＰｉｎＰ（picture in picture）／ＰｂｙＰ（picture by picture）などを用いた表示）が求められている。 In business such as medical use or graphic design, it is used for diagnosis and expression of colors, so that it is necessary to reproduce color numerically accurately for an image display device (display). For this reason, image display devices are required to be accurate in luminance and chromaticity of an image displayed on the display screen and uniform in the display screen.
Further, in recent years, image display apparatuses have been integrated with display of medical image diagnosis (X-ray images) and office electronic medical records that have been operated on different apparatuses, for example, as the display screen has been enlarged. Display using PinP (picture in picture) / PbyP (picture by picture) is required.
　すなわち、画像表示装置の表示画面内において、この表示画面に表示される異なる複数のアプリケーションの画面の各々が、それぞれの独立した画質設定に対応した画像を正確に表示することが求められている。
　このため、画像表示装置においては、映像表示部（液晶パネルやバックライト）における、例えば図７に示す表示画面の表示ムラを補正し、表示画面内で均一な表示を実現している（例えば、特許文献１参照）。
　図７は、画像表示装置の表示画面内における表示ムラの一例を示す３次元グラフである。一般的に、表示画面内における表示ムラは、個々の画像表示装置によって状態が異なる。この図７は、画像表示装置の表示画面における水平方向の位置に対応するｘ軸及び垂直方向の位置に対応するｙ軸の各々の座標値で設定される画素におけるｚ軸の画面輝度値[cd/m２]を示している。すなわち、各画素が同じ階調の画像を表示したときの画像表示装置の表示画面における表示ムラ（画面輝度値の不均一性）を示している。 That is, in the display screen of the image display device, it is required that each of a plurality of different application screens displayed on the display screen accurately display an image corresponding to each independent image quality setting.
Therefore, in the image display device, for example, display unevenness of the display screen shown in FIG. 7 in the video display unit (liquid crystal panel or backlight) is corrected, and uniform display is realized in the display screen (for example, Patent Document 1).
FIG. 7 is a three-dimensional graph showing an example of display unevenness in the display screen of the image display apparatus. Generally, the state of display unevenness in the display screen differs depending on the individual image display device. FIG. 7 shows the screen brightness value [cd of the z axis in the pixel set by the coordinate values of the x axis corresponding to the horizontal position and the y axis corresponding to the vertical position on the display screen of the image display device. / m 2 ]. That is, the display unevenness (nonuniformity of the screen luminance value) on the display screen of the image display device when each pixel displays an image of the same gradation.
特開２００７－２１９０６２号公報Japanese Patent Laid-Open No. 2007-219062
　特許文献１のような表示装置の場合、表示画面における独立した黒レベルをそれぞれ有する画面において、それぞれの画面の独立した画質設定に対応した画像を正確に表示することが困難である。
　すなわち、図８に示すように、特許文献１の画像表示装置２００において、画像オフセット回路２０１は、画像入力部２０２を介して入力される画面画像の黒レベルを、予め画質設定記憶部２０３に設定された黒レベル（黒レベル補正データ）によりオフセット調整する。また、画像オフセット回路２０４は、画像入力部２０５を介して入力される画面画像の黒レベル（画像オフセット回路２０１に入力される黒ラベルと独立に設定された黒レベル）を、画質設定記憶部２０３に設定された黒レベルによりオフセット調整する。 In the case of a display device such as Patent Document 1, it is difficult to accurately display an image corresponding to an independent image quality setting of each screen on a screen having independent black levels on the display screen.
That is, as shown in FIG. 8, in the image display apparatus 200 of Patent Document 1, the image offset circuit 201 sets the black level of the screen image input via the image input unit 202 in the image quality setting storage unit 203 in advance. The offset is adjusted according to the black level (black level correction data). The image offset circuit 204 also displays the black level of the screen image input via the image input unit 205 (the black level set independently of the black label input to the image offset circuit 201), and the image quality setting storage unit 203. Adjust the offset according to the black level set to.
　そして、画像合成回路２０６は、画像オフセット回路２０１及び２０４の各々から出力される、それぞれオフセット調整された画面画像を合成して、表示画面画像を生成する。黒ムラ補正回路２０７は、画質設定記憶部２０３に設定されたムラ補正設定である黒ムラ補正データにより、表示画面画像の黒ムラ補正を行ない、画像表示部２０８に対して出力する。ここで、黒ムラ補正回路２０７は、画像表示部２０８の表示ムラを表示画面内で均一な表示とするムラ補正によって、黒ムラの補正を行なっている。画像表示部２０８は、液晶パネルであり、黒ムラ補正回路２０７から供給される表示画面画像を、表示画面に対して表示する。この図８は、特許文献１の画像表示装置の概念図である。 Then, the image composition circuit 206 synthesizes the screen images adjusted by the offsets output from the image offset circuits 201 and 204, and generates a display screen image. The black unevenness correction circuit 207 performs black unevenness correction of the display screen image based on the black unevenness correction data which is the unevenness correction setting set in the image quality setting storage unit 203 and outputs the black image to the image display unit 208. Here, the black unevenness correction circuit 207 performs black unevenness correction by unevenness correction that makes the display unevenness of the image display unit 208 uniform display on the display screen. The image display unit 208 is a liquid crystal panel, and displays the display screen image supplied from the black unevenness correction circuit 207 on the display screen. FIG. 8 is a conceptual diagram of the image display device of Patent Document 1.
　このため、特許文献１の画像表示装置は、黒レベルの設定とは異なる表示画面内の黒ムラ（表示ムラ）のムラ補正を行なっており、この２つの独立した黒レベルの設定の組合わせにより、画像表示部２０８の表示画面に表示される各画面における画質が決定される。しかしながら、黒ムラ補正回路２０７において表示画面のムラ補正を行なわれることにより、画像表示部２０８の表示画面全体の黒レベルが上昇して、表示画面に表示される画面毎における希望するコントラスト特性が得られなくなる。 For this reason, the image display device disclosed in Patent Document 1 corrects unevenness of black unevenness (display unevenness) in the display screen, which is different from the setting of the black level, and a combination of these two independent black level settings. The image quality on each screen displayed on the display screen of the image display unit 208 is determined. However, the black unevenness correction circuit 207 performs unevenness correction of the display screen, whereby the black level of the entire display screen of the image display unit 208 is increased, and a desired contrast characteristic for each screen displayed on the display screen is obtained. It becomes impossible.
　上述の課題を鑑み、本発明は、表示画面に表示される複数の画面毎に適切な画像を表示することができる画像表示装置および画像表示方法を提供することを目的とする。 In view of the above-described problems, an object of the present invention is to provide an image display device and an image display method capable of displaying an appropriate image for each of a plurality of screens displayed on a display screen.
　本発明は、液晶パネルの表示画面に表示される複数の画面の黒ムラを補正して表示する画像表示装置であり、前記画面毎に設定される黒レベルに基づくオフセット量により、前記画面それぞれの前記黒レベルを調整する画像オフセット部と、前記黒レベルと前記画面毎に設定される白レベルとにより、前記表示画面全体におけるムラ補正を行なう黒ムラ補正部とを備えることを特徴とする画像表示装置である。 The present invention is an image display apparatus that corrects and displays black unevenness of a plurality of screens displayed on a display screen of a liquid crystal panel, and each of the screens has an offset amount based on a black level set for each screen. An image display comprising: an image offset unit that adjusts the black level; and a black unevenness correcting unit that performs unevenness correction on the entire display screen based on the black level and a white level set for each screen. Device.
　本発明は、液晶パネルの表示画面に表示される複数の画面の各々の黒ムラを補正して表示する画像表示であり、画像オフセット部が、前記画面毎に設定される黒レベルに基づくオフセット量により、前記画面それぞれの前記黒レベルを調整する画像オフセット過程と、黒ムラ補正部が、前記黒レベルと前記画面毎に設定される白レベルとにより、前記表示画面全体におけるムラ補正を行なう黒ムラ補正過程とを含むことを特徴とする画像表示方法である。 The present invention is an image display that corrects and displays black unevenness of each of a plurality of screens displayed on a display screen of a liquid crystal panel, and an image offset unit is an offset amount based on a black level set for each screen Therefore, the black offset for adjusting the black level of each of the screens, and the black unevenness correction unit performs unevenness correction on the entire display screen based on the black level and the white level set for each screen. And a correction process.
　本発明によれば、表示画面に表示される複数の画面毎に適切な画像を表示することができる。 According to the present invention, it is possible to display an appropriate image for each of a plurality of screens displayed on the display screen.
本発明の実施形態による画像表示装置１の構成例を示す図である。It is a figure which shows the structural example of the image display apparatus 1 by embodiment of this invention. 本実施形態における、目標コントラストが１００：１の場合の黒ムラ補正を行なったときの表示ムラの一例を示す図である。It is a figure which shows an example of the display nonuniformity when performing black nonuniformity correction in case this target contrast is 100: 1. 本実施形態における、目標コントラストが３０：１の場合の黒ムラ補正を行なったときの表示ムラの一例を示す図である。It is a figure which shows an example of the display nonuniformity when performing black nonuniformity correction | amendment in case this target contrast is 30: 1. 本実施形態における、目標コントラストが１０：１の場合の黒ムラ補正を行なったときの表示ムラの一例を示す図である。It is a figure which shows an example of the display nonuniformity when performing black nonuniformity correction in case this target contrast is 10: 1 in this embodiment. 本発明の実施形態の概念を説明する図である。It is a figure explaining the concept of embodiment of this invention. 画像表示装置１が行う液晶パネル２１に表示画面画像を表示する処理例を示すフローチャートである。4 is a flowchart illustrating a processing example of displaying a display screen image on a liquid crystal panel 21 performed by the image display device 1. 画像表示装置の表示画面内における表示ムラの一例を示す３次元グラフである。It is a three-dimensional graph which shows an example of the display nonuniformity in the display screen of an image display apparatus. 特許文献１の画像表示装置の概念図である。1 is a conceptual diagram of an image display device of Patent Document 1. FIG.
　以下、本発明の実施形態による画像表示装置について図面を参照して説明する。図１は、本発明の実施形態による画像表示装置１の構成例を示す図である。
　図１に示すように、画像表示装置１は、黒輝度算出部１１、オフセット量算出部１２、最小黒輝度選択部１３、最大輝度選択部１４、黒ムラ補正量計算部１５、画像入力部１６、画像オフセット部１７、画像合成部１８、黒ムラ補正部１９、記憶部２０及び液晶パネル２１を備えている。 Hereinafter, an image display device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of an image display device 1 according to an embodiment of the present invention.
As shown in FIG. 1, the image display device 1 includes a black luminance calculation unit 11, an offset amount calculation unit 12, a minimum black luminance selection unit 13, a maximum luminance selection unit 14, a black unevenness correction amount calculation unit 15, and an image input unit 16. , An image offset unit 17, an image composition unit 18, a black unevenness correction unit 19, a storage unit 20, and a liquid crystal panel 21.
　本実施形態においては、液晶パネル２１の表示画面に表示される画面（例えば、ウィンドウ表示）毎に黒レベルと白レベルとが、表示画面の設定としてユーザにより入力される。すなわち、ユーザは、液晶パネル２１の表示画面における画面毎に、希望する白レベル及び黒レベルの各々を、画像表示装置１に対して設定する。設定値の単位と範囲とは任意であるが、本実施形態においては、白レベル及び黒レベルの各々の単位及び範囲を、それぞれ０～１００[％]とする。白レベルは、所定の画面に表示される画像の最も明るい輝度（最大階調を表示したときの輝度）に対応する。黒レベルは、所定の画面に表示される画像の最も暗い輝度（最小階調を表示したときの輝度）に対応する。白レベルは、バックライトの出力や画像信号の最大レベル（液晶パネル２１の画素における光の最大透過率）を可変して制御する。黒レベルは、画像信号の最小レベル（液晶パネル２１の画素における光の最小透過率）を可変する。バックライトや画像信号を可変して制御する動作は、一般的な液晶パネルと同様である。表示画面は、例えば、ＰｉｎＰ（picture in picture）、ＰｂｙＰ（picture by picture）などを用いて表示される。すなわち、ＰｉｎＰとして表示する場合、表示領域の一部の領域に第２の画面が表示され、第２の画面を除く表示領域全体に第１の画面が表示される。また、ＰｉｎＰ（picture in picture）として表示する場合、表示領域を２つに分割し、一方の領域に第１の画面が表示され、他方の画面に第２の画面が表示される。なお、２つの画面（第１の画面、第２の画面）について説明したが、３つの画面（第１の画面、第２の画面、第３の画面）など、複数の画面が表示されるようにしてもよい。 In the present embodiment, the black level and the white level are input by the user as display screen settings for each screen (for example, window display) displayed on the display screen of the liquid crystal panel 21. That is, the user sets each desired white level and black level for the image display device 1 for each screen on the display screen of the liquid crystal panel 21. The unit and range of the set value are arbitrary, but in this embodiment, the unit and range of each of the white level and the black level are 0 to 100%. The white level corresponds to the brightest luminance of the image displayed on a predetermined screen (the luminance when the maximum gradation is displayed). The black level corresponds to the darkest brightness of the image displayed on the predetermined screen (the brightness when the minimum gradation is displayed). The white level is controlled by varying the maximum output level of the backlight and the image signal (the maximum light transmittance in the pixels of the liquid crystal panel 21). The black level varies the minimum level of the image signal (the minimum light transmittance in the pixels of the liquid crystal panel 21). The operation of changing and controlling the backlight and the image signal is the same as that of a general liquid crystal panel. The display screen is displayed using, for example, PinP (picture in picture), PbyP (picture by picture), and the like. That is, when displaying as PinP, a 2nd screen is displayed in the one part area | region of a display area, and a 1st screen is displayed in the whole display area except a 2nd screen. Also, when displaying as PinP (picture in picture), the display area is divided into two, the first screen is displayed in one area, and the second screen is displayed in the other screen. Although two screens (the first screen and the second screen) have been described, a plurality of screens such as three screens (the first screen, the second screen, and the third screen) are displayed. It may be.
　黒輝度算出部１１は、ユーザが設定した画面毎の黒レベルと白レベルとから、画面各々における黒レベルの絶対値（各画面に表示される際の実際に輝度）である黒輝度を算出する。黒輝度として、表示画面における正確な黒画面輝度[cd/m２]の算出が望ましい。しかしながら、本実施形態においては、簡便に黒レベルと白レベルとの各々を乗算した結果を黒輝度として求める。すなわち、黒輝度は、表示画面に最小階調の画像を表示したときの輝度に対応している。 The black luminance calculation unit 11 calculates black luminance that is an absolute value of the black level in each screen (actual luminance when displayed on each screen) from the black level and white level for each screen set by the user. . As black luminance, it is desirable to calculate accurate black screen luminance [cd / m 2 ] on the display screen. However, in the present embodiment, the result of simply multiplying each of the black level and the white level is obtained as the black luminance. That is, the black luminance corresponds to the luminance when an image with the minimum gradation is displayed on the display screen.
　例えば、液晶パネル２１の表示画面に画面Ｐ１（第１の画面）及び画面Ｐ２（第２の画面）の各々が表示される際に、画面Ｐ１の黒レベルが１０％、白レベルが３０％として設定された場合、黒輝度は０．０３（＝０．１×０．３）と求められる。同様に、画面Ｐ２の黒レベルが５％、白レベルが１００％として設定された場合、黒輝度は０．０５（＝０．０５×１．０）と求められる。黒レベルは、液晶パネル２０の画素における光の透過率を示している。白レベルは、最大輝度値であり、バックライト（不図示）の最大照度に対する比率を示している。なお、液晶パネル２０は、バックライトが発する光を映像信号に基づいて変調して画像を表示する。 For example, when each of the screen P1 (first screen) and the screen P2 (second screen) is displayed on the display screen of the liquid crystal panel 21, the black level of the screen P1 is 10% and the white level is 30%. When set, the black luminance is determined to be 0.03 (= 0.1 × 0.3). Similarly, when the black level of the screen P2 is set to 5% and the white level is set to 100%, the black luminance is obtained as 0.05 (= 0.05 × 1.0). The black level indicates the light transmittance in the pixels of the liquid crystal panel 20. The white level is a maximum luminance value and indicates a ratio with respect to the maximum illuminance of a backlight (not shown). The liquid crystal panel 20 displays an image by modulating the light emitted from the backlight based on the video signal.
　液晶パネル２１の表示画面に表示される画面の各々において、それぞれ独立した黒レベル及び白レベルを適切に再現するため、画面間における白レベル及び黒レベルの大小を明確化する必要がある。黒レベルは、白レベルに対する相対値である。このため、白レベルとは異なり、黒レベル自体では、画面間における大小を明確化することができない。本実施形態においては、上述した黒輝度を算出し、画面間における黒レベルの相対評価を行なっている。 In each of the screens displayed on the display screen of the liquid crystal panel 21, in order to appropriately reproduce the independent black level and white level, it is necessary to clarify the magnitude of the white level and black level between the screens. The black level is a relative value with respect to the white level. For this reason, unlike the white level, the black level itself cannot clarify the size between screens. In the present embodiment, the above-described black luminance is calculated and the relative evaluation of the black level between the screens is performed.
　最小黒輝度選択部１３は、黒輝度算出部１１が求めた各画面における黒輝度の中で、最も小さな黒輝度（最小黒輝度）を選択する。また、最小黒輝度選択部１３は、選択した最小黒輝度を黒ムラ補正量計算部１５に対して出力する。ここで、本実施形態の場合、最小黒輝度選択部１３は、画面Ｐ１の黒輝度０．０３を選択する。 The minimum black luminance selection unit 13 selects the smallest black luminance (minimum black luminance) among the black luminances in the respective screens obtained by the black luminance calculation unit 11. In addition, the minimum black luminance selection unit 13 outputs the selected minimum black luminance to the black unevenness correction amount calculation unit 15. Here, in the present embodiment, the minimum black luminance selection unit 13 selects the black luminance 0.03 of the screen P1.
　最大輝度選択部１４は、画面の各々の白レベルから、最大の輝度値（白輝度）、すなわち最大の白レベル（最大白レベル）を選択する。また、最小黒輝度選択部１３は、選択した最大白レベルを黒ムラ補正量計算部１５に対して出力する。本実施形態の場合、最大輝度選択部１４は、画面Ｐ２の白レベル１．０を選択する。 The maximum brightness selection unit 14 selects the maximum brightness value (white brightness), that is, the maximum white level (maximum white level) from each white level of the screen. Further, the minimum black luminance selection unit 13 outputs the selected maximum white level to the black unevenness correction amount calculation unit 15. In the present embodiment, the maximum luminance selection unit 14 selects the white level 1.0 of the screen P2.
　画像入力部１６は、外部機器から液晶パネル２１の画像表示面に表示される画面の各々の画面表示画像それぞれを入力する。 The image input unit 16 inputs each screen display image of the screen displayed on the image display surface of the liquid crystal panel 21 from an external device.
　オフセット量算出部１２は、画面の黒輝度と、最小黒輝度と、最大白レベルとの各々により、画像オフセット補正量の算出を行なう。ここで、オフセット量算出部１２は、画面の黒輝度の各々から、最小黒輝度を減算し、減算結果として画面それぞれの差分輝度を求める。そして、オフセット量算出部１２は、画面の差分輝度の各々を、最大白レベルで除算し、画面それぞれの画像オフセット補正量を求める。また、オフセット量算出部１２は、求めた画像オフセット補正量を画像オフセット部１７へ出力する。 The offset amount calculation unit 12 calculates an image offset correction amount based on each of the black luminance, the minimum black luminance, and the maximum white level of the screen. Here, the offset amount calculation unit 12 subtracts the minimum black luminance from each of the black luminances of the screen, and obtains the differential luminance of each screen as the subtraction result. Then, the offset amount calculation unit 12 divides each difference luminance of the screen by the maximum white level to obtain an image offset correction amount for each screen. Further, the offset amount calculation unit 12 outputs the obtained image offset correction amount to the image offset unit 17.
　例えば、最小黒輝度が０．０３であるため、画面Ｐ１の画面表示画像の差分輝度は、０．０（＝０．０３－０．０３）となる。一方、画面Ｐ２の画面表示画像の差分輝度は、０．０２（＝０．０５－０．０３）となる。また、最大白レベルが１であるため、画面Ｐ１及び画面Ｐ２の各々の画面表示画像の画像オフセット補正量は、それぞれ０．０（＝０．０／１．０）、０．０２（＝０．０２／１．０）となる。 For example, since the minimum black luminance is 0.03, the difference luminance of the screen display image of the screen P1 is 0.0 (= 0.03 to 0.03). On the other hand, the difference luminance of the screen display image of the screen P2 is 0.02 (= 0.05−0.03). Since the maximum white level is 1, the image offset correction amounts of the screen display images of the screen P1 and the screen P2 are 0.0 (= 0.0 / 1.0) and 0.02 (= 0, respectively. .02 / 1.0).
　画像オフセット部１７は、オフセット量算出部１２から供給される画像オフセット補正量に基づいて、画面の各々の画面表示画像の黒レベルを上昇させる。すなわち、画像オフセット部１７は、画面表示画像の各画素の階調を画像オフセット量分上昇させる処理を行ない、補正後の階調からなる画面表示画像を出力する。本実施形態において、画像オフセット部１７は、画面Ｐ１の画面表示画像に対する画像オフセット補正量が０であるため、画面Ｐ１の画面表示画像に対するオフセットによる補正を行なわない。一方、画像オフセット部１７は、画面Ｐ２の画面表示画像に対する画像オフセット補正量が０．０２であるため、画面Ｐ２の画面表示画像の各々の階調を画像オフセット補正量０．０２分上昇させる補正を行う。 The image offset unit 17 increases the black level of each screen display image on the screen based on the image offset correction amount supplied from the offset amount calculation unit 12. That is, the image offset unit 17 performs a process of increasing the gradation of each pixel of the screen display image by the amount of the image offset, and outputs a screen display image having the corrected gradation. In the present embodiment, since the image offset correction amount for the screen display image of the screen P1 is 0, the image offset unit 17 does not perform correction by the offset for the screen display image of the screen P1. On the other hand, since the image offset correction amount with respect to the screen display image of the screen P2 is 0.02, the image offset unit 17 performs a correction to increase each gradation of the screen display image of the screen P2 by the image offset correction amount 0.02. I do.
　画像合成部１８は、画像オフセット部１７がオフセット補正を行なった画面Ｐ１の画面表示画像と画面Ｐ２の画面表示画像との各々を、液晶パネル２１の表示画面に表示する表示画面画像として合成する。そして、画像合成部１８は、合成した表示画面画像を、黒ムラ補正部１９に対して出力する。 The image composition unit 18 synthesizes each of the screen display image of the screen P1 and the screen display image of the screen P2 on which the offset correction has been performed by the image offset unit 17 as a display screen image to be displayed on the display screen of the liquid crystal panel 21. Then, the image composition unit 18 outputs the synthesized display screen image to the black unevenness correction unit 19.
　黒ムラ補正量計算部１５は、最大白レベルと最小黒輝度とから目標コントラスト比を算出する。本実施形態において、黒ムラ補正量計算部１５は、最大白レベルが白レベル１であり、最小黒輝度が黒輝度０．０３であるため、目標コントラスト比が１００：３（≒３３：１）として算出される。このコントラスト比の計算方法は、簡易的な計算であり、さらに係数を乗じるなどする正確なコントラスト比を計算できる手順を用いても良い。黒ムラ補正量計算部１５は、目標コントラスト比と、表示ムラ調整時におけるコントラスト比である調整時コントラスト比とを比較し、目標コントラスト比が得られるように、黒ムラ補正量を求める。
　記憶部２０には、調整時コントラスト比が予め書き込まれて記憶されている。以下、この調整時コントラスト比について説明する。 The black unevenness correction amount calculation unit 15 calculates a target contrast ratio from the maximum white level and the minimum black luminance. In the present embodiment, since the maximum white level is white level 1 and the minimum black luminance is black luminance 0.03, the black unevenness correction amount calculation unit 15 has a target contrast ratio of 100: 3 (≈33: 1). Is calculated as This method of calculating the contrast ratio is a simple calculation, and a procedure that can calculate an accurate contrast ratio such as multiplication by a coefficient may be used. The black unevenness correction amount calculation unit 15 compares the target contrast ratio with the adjustment contrast ratio that is the contrast ratio at the time of display unevenness adjustment, and obtains the black unevenness correction amount so that the target contrast ratio is obtained.
In the storage unit 20, the adjustment contrast ratio is written and stored in advance. Hereinafter, this adjustment contrast ratio will be described.
　液晶パネル２１を製造した際または表示装置を製造した際など、この液晶パネル２１の表示画面の表示ムラを補正するための基準となるムラ補正（表示ムラ）データを決定し、予め記憶部２０に書き込んで記憶させておく。このムラ補正データ（補正値）は、一般的に、色（例えば、Ｒ（レッド）、Ｇ（グリーン）及びＢ（ブルー）の各々）と、階調（階調２５５、１９２、１２８、６４、０）の各々との組合わせ毎に、上記表示画面における位置（例えば、表示画面の画素の配列において、所定の横２０画素、縦１１画素）に対応して、それぞれ独立したルックアップテーブルとして記憶部２０に書き込まれて記憶されている。これらの補正値は、表示画面における画素の位置、画素の階調に対して全て設定されているのではなく、記憶部２０の記憶容量の増加を抑制するため、所定の代表的な階調あるいは所定の間隔に散布された位置の画素に対して設定されている。液晶パネルのムラ補正は、ムラ補正データを用いて行われる。なお、黒ムラ補正は階調０のムラ補正に対応する。 When the liquid crystal panel 21 is manufactured or when a display device is manufactured, unevenness correction (display unevenness) data serving as a reference for correcting display unevenness of the display screen of the liquid crystal panel 21 is determined and stored in the storage unit 20 in advance. Write and remember. The unevenness correction data (correction value) generally includes color (for example, each of R (red), G (green), and B (blue)) and gradation (gradation 255, 192, 128, 64, 0) is stored as an independent look-up table corresponding to each position on the display screen (for example, a predetermined 20 horizontal pixels and 11 vertical pixels in the display screen pixel arrangement). It is written and stored in the unit 20. These correction values are not all set with respect to the pixel position and pixel gradation on the display screen, but to suppress an increase in the storage capacity of the storage unit 20, a predetermined representative gradation or It is set for pixels at positions scattered at predetermined intervals. The unevenness correction of the liquid crystal panel is performed using unevenness correction data. Note that black unevenness correction corresponds to gradation 0 unevenness correction.
　したがって、補正値が存在する画素間にある、補正値が存在しない画素に対しては、補正値が存在する最も近接する２つの画素の補正値の直線補完などにより、補正値を求めることになる。同様に、補正値が存在する階調間にある、補正値が存在しない階調に対しては、補正値が存在する最も近接する２つの階調の補正値の直線補完などにより、補正値を求めることになる。
　表示画面における表示ムラ調節は、例えば、ＣＣＤ（charge coupled device）などの撮像素子により取得した２次元輝度分布（表示ムラ分布）に基づいて、表示ムラが低減される補正値を求めることで行なう。すなわち、液晶パネル２１の製造時において、表示画面における各位置の画素の階調を全て同一とし、表示ムラが均一となるように、その階調となる各画素の補正値を求める。これをすでに述べた代表的な階調毎に行ない、それぞれの階調における補正値を求める。 Therefore, for pixels that do not have a correction value between pixels that have a correction value, the correction value is obtained by, for example, linear interpolation of the correction values of the two adjacent pixels that have the correction value. . Similarly, for gradations between which there is a correction value, and where there is no correction value, the correction value is set by linear interpolation of the correction values of the two closest gradations where the correction value exists. Will be asked.
The display unevenness adjustment on the display screen is performed by obtaining a correction value for reducing the display unevenness based on a two-dimensional luminance distribution (display unevenness distribution) acquired by an image sensor such as a CCD (charge coupled device). That is, at the time of manufacturing the liquid crystal panel 21, all the gradations of the pixels at each position on the display screen are made the same, and the correction value of each pixel having the gradation is obtained so that the display unevenness is uniform. This is performed for each representative gradation already described, and a correction value for each gradation is obtained.
　そして、調整時コントラスト比は、上述した表示ムラが均一となるように補正した際における、表示画面の中央の位置における画素の黒レベルと白レベルとのコントラスト比として求められ、予め記憶部２０に書き込まれている。また、表示画面の中央の位置における画素の黒ムラ補正を行なわない場合のコントラスト比を、無補正コントラスト比として、記憶部２０に書き込んで記憶させる。表示ムラ（黒ムラ補正）の補正を行なった場合、原理的に白レベルの輝度が低下し、黒レベルの輝度が上昇する。このため、調整時コントラスト比は、無補正コントラスト比に対して低下することになる。例えば、無補正コントラスト比が１０００：１であっても、表示ムラの補正を行なった場合、調整時コントラスト比として３００：１に低下する。 The adjustment contrast ratio is obtained as the contrast ratio between the black level and the white level of the pixel at the center position of the display screen when the above-described display unevenness is corrected, and is stored in the storage unit 20 in advance. Has been written. Further, the contrast ratio when the black unevenness correction of the pixel at the center position of the display screen is not performed is written and stored in the storage unit 20 as an uncorrected contrast ratio. When display unevenness (black unevenness correction) is corrected, in principle, the brightness of the white level decreases and the brightness of the black level increases. For this reason, the contrast ratio at the time of adjustment is lower than the uncorrected contrast ratio. For example, even when the uncorrected contrast ratio is 1000: 1, when the display unevenness is corrected, the contrast ratio during adjustment is reduced to 300: 1.
　黒ムラ補正量計算部１５は、上述した記憶部２０に記憶されている調整時コントラスト比を参照して、ルックアップテーブルにおける表示ムラの補正値を用いて目標コントラスト比が実現できるように、表示画面画像の各々の画素の黒ムラ補正量を算出する。ここで、記憶部２０に記憶されているルックアップテーブルにおける表示ムラの補正値は、調整時コントラスト比に対応している。このため、ルックアップテーブルの補正値をそのまま用いた場合、ユーザが希望とする目標コントラスト比が得られない。 The black unevenness correction amount calculation unit 15 refers to the adjustment contrast ratio stored in the storage unit 20 and displays the target contrast ratio so that the target contrast ratio can be realized using the display unevenness correction value in the lookup table. A black unevenness correction amount of each pixel of the screen image is calculated. Here, the display unevenness correction value in the lookup table stored in the storage unit 20 corresponds to the adjustment contrast ratio. For this reason, when the correction value of the lookup table is used as it is, the target contrast ratio desired by the user cannot be obtained.
　黒ムラ補正量計算部１５は、目標コントラスト比が得られるように、以下の処理を行なう。まず、黒ムラ補正量計算部１５は、記憶部２０から調整時コントラスト比と無補正コントラスト比とを読み出す。また、黒ムラ補正量計算部１５は、表示画面画像における画素の各々の階調及び液晶パネル２１の位置に対応して、それぞれの画素の階調に対するムラ補正量を、記憶部２０のルックアップテーブルを参照して計算する。すでに述べたように、黒ムラ補正量計算部１５は、対象の画素がルックアップテーブルに存在する代表位置であり、かつ代表の階調であれば、その位置及び階調に対応するムラ補正量を、その画素の補正値とする。一方、黒ムラ補正量計算部１５は、対象の画素がルックアップテーブルに存在する代表位置でないか、あるいは代表の階調でない場合、代表位置及び代表の階調の各々から直線補完などを用いて算出する。 The black unevenness correction amount calculation unit 15 performs the following processing so as to obtain the target contrast ratio. First, the black unevenness correction amount calculation unit 15 reads the adjustment contrast ratio and the uncorrected contrast ratio from the storage unit 20. Further, the black unevenness correction amount calculation unit 15 looks up the unevenness correction amount for the gradation of each pixel corresponding to the gradation of each pixel and the position of the liquid crystal panel 21 in the display screen image. Calculate with reference to the table. As described above, the black unevenness correction amount calculation unit 15 is the representative position where the target pixel exists in the lookup table and is a representative gradation, and the unevenness correction amount corresponding to that position and gradation. Is a correction value of the pixel. On the other hand, if the target pixel is not a representative position existing in the lookup table or is not a representative gradation, the black unevenness correction amount calculation unit 15 uses linear interpolation or the like from each of the representative position and the representative gradation. calculate.
　また、黒ムラ補正量計算部１５は、目標コントラスト比と、調整時コントラスト比及び無補正コントラスト比の各々とを比較する。そして、黒ムラ補正量計算部１５は、目標コントラスト比が調整時コントラスト比以下であれば、上述したように求めた階調値（ムラ補正量）を黒ムラ補正量として、黒ムラ補正部１９に対して出力する。
　一方、黒ムラ補正量計算部１５は、目標コントラスト比が無補正コントラスト比を超えている場合、黒ムラ補正量を「０」として、黒ムラ補正部１９に対して出力する。また、黒ムラ補正量計算部１５は、目標コントラスト比が、調整時コントラスト比を超え、かつ無補正コントラスト比未満である場合、目標コントラスト比から調整時コントラスト比を減算した減算結果を、無補正コントラスト比から調整時コントラスト比から減算した減算結果により除算し、１から除算結果を減算した数値を調整量とする。そして、黒ムラ補正量計算部１５は、求めたムラ補正量に対して上記調整量を乗算し、この乗算結果を黒ムラ補正量として、黒ムラ補正部１９に対して出力する。 Further, the black unevenness correction amount calculation unit 15 compares the target contrast ratio with each of the adjustment contrast ratio and the uncorrected contrast ratio. Then, if the target contrast ratio is equal to or smaller than the adjustment contrast ratio, the black unevenness correction amount calculation unit 15 uses the gradation value (unevenness correction amount) obtained as described above as the black unevenness correction amount, and the black unevenness correction unit 19. Output for.
On the other hand, when the target contrast ratio exceeds the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 sets the black unevenness correction amount to “0” and outputs it to the black unevenness correction unit 19. In addition, the black unevenness correction amount calculation unit 15 performs non-correction on the subtraction result obtained by subtracting the adjustment contrast ratio from the target contrast ratio when the target contrast ratio exceeds the adjustment contrast ratio and less than the non-correction contrast ratio. Division is performed by a subtraction result obtained by subtracting the contrast ratio from the contrast ratio at the time of adjustment, and a numerical value obtained by subtracting the division result from 1 is used as the adjustment amount. Then, the black unevenness correction amount calculation unit 15 multiplies the obtained unevenness correction amount by the adjustment amount and outputs the multiplication result to the black unevenness correction unit 19 as a black unevenness correction amount.
　上述した処理において、各画面において設定された白レベルと黒レベルとから求めた黒輝度を、目標コントラスト比と調整時コントラスト比との比較に対応して、最大白レベルに対する相対的な黒レベルに再度変換している。この変換は、黒ムラ補正が表示画面画像の表示ムラの補正であり、白レベル（最大白レベル）を輝度の最大値（基準値）として、この白レベルに対する相対値として、表示ムラの補正に用いる黒ムラ補正量を算出するために行なわれる。一般的に、液晶パネル２１などの液晶ディスプレイにおける絶対的な輝度は、バックライトの照射光の制御により決定される。このため、オフセット量、黒ムラ補正量などの画像補正値は、白レベルに対する相対値として求める必要がある。 In the above-described processing, the black luminance obtained from the white level and the black level set on each screen is set to a relative black level with respect to the maximum white level in correspondence with the comparison between the target contrast ratio and the adjustment contrast ratio. It is converted again. In this conversion, the black unevenness correction is correction of display unevenness of the display screen image. The white level (maximum white level) is set as the maximum luminance value (reference value), and the relative value to the white level is used to correct the display unevenness. This is performed to calculate the black unevenness correction amount to be used. In general, the absolute luminance in a liquid crystal display such as the liquid crystal panel 21 is determined by controlling the irradiation light of the backlight. For this reason, it is necessary to obtain image correction values such as the offset amount and the black unevenness correction amount as relative values with respect to the white level.
　図２は、本実施形態における、目標コントラストが１００：１の場合の黒ムラ補正を行なったときの表示ムラの一例を示す図である。図３は、本実施形態における、目標コントラストが３０：１の場合の黒ムラ補正を行なったときの表示ムラの一例を示す図である。図４は、本実施形態における、目標コントラストが１０：１の場合の黒ムラ補正を行なったときの表示ムラの一例を示す図である。なお、表示画面内における表示ムラは、個々の表示パネルによって異なる。
　図２、図３及び図４の各々において、ｘ軸は液晶パネル２１の表示画面の横方向（例えば、長尺方向、または水平方向）の画素の位置を示している。また、ｙ軸は液晶パネル２１の表示画面の縦方向（例えば、短尺方向、または垂直方向）の画素の位置を示している。ｚ軸は、ｘ軸におけるｘ座標とｙ軸におけるｙ座標とにより示される、表示画面の画素の位置における画面輝度[cd/m２]を示している。この画面輝度は、黒ムラ補正量に対応している。
　図２、図３及び図４の各々に示されるように、目標コントラスト比が小さくなるに従い、輝度を補正する黒ムラ補正量が増加する。すなわち、図２は、黒ムラ補正がかかっていない、またはほとんどかかっていない状態を示す。図３は、表示画面の最低輝度が０．４[cd/m２]程度になるように黒ムラ補正をかけた状態を示す。また、図４は、表示画面の最低輝度が０．６[cd/m２]程度になるように黒ムラ補正をかけた状態を示す。 FIG. 2 is a diagram illustrating an example of display unevenness when black unevenness correction is performed when the target contrast is 100: 1. FIG. 3 is a diagram illustrating an example of display unevenness when black unevenness correction is performed when the target contrast is 30: 1 in the present embodiment. FIG. 4 is a diagram illustrating an example of display unevenness when black unevenness correction is performed when the target contrast is 10: 1 in the present embodiment. The display unevenness in the display screen varies depending on the individual display panel.
In each of FIGS. 2, 3, and 4, the x-axis indicates the pixel position in the horizontal direction (for example, the longitudinal direction or the horizontal direction) of the display screen of the liquid crystal panel 21. Further, the y-axis indicates the pixel position in the vertical direction (for example, the short direction or the vertical direction) of the display screen of the liquid crystal panel 21. The z-axis indicates the screen brightness [cd / m 2 ] at the pixel position on the display screen indicated by the x-coordinate on the x-axis and the y-coordinate on the y-axis. This screen brightness corresponds to the black unevenness correction amount.
As shown in FIG. 2, FIG. 3, and FIG. 4, as the target contrast ratio decreases, the black unevenness correction amount for correcting the luminance increases. That is, FIG. 2 shows a state where black unevenness correction is not applied or hardly applied. FIG. 3 shows a state in which black unevenness correction is performed so that the minimum luminance of the display screen is about 0.4 [cd / m 2 ]. FIG. 4 shows a state in which the black unevenness correction is performed so that the minimum luminance of the display screen is about 0.6 [cd / m 2 ].
　黒ムラ補正部１９は、表示画面画像の各画素の階調を、黒ムラ補正量計算部１５が求めた黒ムラ補正量に対応した階調値により補正する。そして、黒ムラ補正部１９は、各画素の階調が補正された表示画面画像を、液晶パネル２１に対して出力する。
　液晶パネル２１は、黒ムラ補正部１９から供給される表示画面画像を、表示画面に対して表示する。 The black unevenness correction unit 19 corrects the gradation of each pixel of the display screen image with a gradation value corresponding to the black unevenness correction amount obtained by the black unevenness correction amount calculation unit 15. Then, the black unevenness correction unit 19 outputs a display screen image in which the gradation of each pixel is corrected to the liquid crystal panel 21.
The liquid crystal panel 21 displays the display screen image supplied from the black unevenness correction unit 19 on the display screen.
　上述したように、本実施形態によれば、液晶パネル２１の表示画面に複数の画面を表示させる際、黒ムラ補正部１９で補正される表示画面画像の全体で共有される最小黒輝度のレベルと、画像オフセット部１７で補正される画面間の黒レベルに基づくオフセットとにより、黒レベルを分割して補正、すなわち２段階で補正することにより、画面毎の画質設定と、表示画面における表示ムラの抑圧（ムラ補正）との各々を両立して行なうことができる。このため、本実施形態によれば、複数の画面の各々に対して、それぞれに独立した黒レベルの設定を行ない、かつ表示画面全体における黒ムラのムラ補正を行なえるため、画面の各々の独立した画質設定に対応した画面表示画像を、それぞれ画面に適切に表示することができる。 As described above, according to the present embodiment, when a plurality of screens are displayed on the display screen of the liquid crystal panel 21, the level of the minimum black luminance shared by the entire display screen image corrected by the black unevenness correction unit 19. And the offset based on the black level between the screens corrected by the image offset unit 17, the black level is divided and corrected, that is, corrected in two stages, so that the image quality setting for each screen and the display unevenness on the display screen Each of the above suppression (unevenness correction) can be performed at the same time. For this reason, according to the present embodiment, independent black levels can be set for each of a plurality of screens, and black unevenness correction for the entire display screen can be performed. The screen display image corresponding to the set image quality can be appropriately displayed on the screen.
　図５は、本発明の実施形態の概念を説明する図である。図５において、本発明の実施形態における画像表示装置１００は、液晶パネルの表示画面に表示される複数の画面の各々の黒ムラを補正して表示する画像表示装置であり、画像オフセット部１７と黒ムラ補正部１９と液晶パネル２１とを備えている。画像オフセット部は、液晶パネル２１の表示画面に表示される画面毎に設定される黒レベルに基づくオフセット量により、画面それぞれの黒レベルの輝度を調整する。黒ムラ補正部１９は、黒レベルと画面毎に設定される白レベルとにより、液晶パネル２１の表示画面に表示される画面を合成した表示画面画像全体におけるムラ補正を行ない、液晶パネル２１に対して、この表示画面画像を出力する。 FIG. 5 is a diagram for explaining the concept of the embodiment of the present invention. In FIG. 5, an image display device 100 according to the embodiment of the present invention is an image display device that corrects and displays black unevenness of each of a plurality of screens displayed on the display screen of the liquid crystal panel. A black unevenness correction unit 19 and a liquid crystal panel 21 are provided. The image offset unit adjusts the luminance of the black level of each screen by an offset amount based on the black level set for each screen displayed on the display screen of the liquid crystal panel 21. The black unevenness correction unit 19 performs unevenness correction on the entire display screen image obtained by synthesizing the screen displayed on the display screen of the liquid crystal panel 21 based on the black level and the white level set for each screen. The display screen image is output.
　これにより、表示画面に表示される複数の画面毎に適切な画像を表示することができる。また、表示画面に表示される複数の画面毎に独立した画質設定に対応した画像を画面に正確に表示することができる。 This makes it possible to display an appropriate image for each of a plurality of screens displayed on the display screen. In addition, an image corresponding to an independent image quality setting for each of a plurality of screens displayed on the display screen can be accurately displayed on the screen.
　図６は、画像表示装置１が行う液晶パネル２１に表示画面画像を表示する処理例を示すフローチャートである。
　ステップＳ１：
　画像入力部１６は、外部機器から液晶パネル２１の表示画面に表示する画面の各々の画面表示画像を入力する。
　また、図示しない入力手段から、ユーザによって画面の各々に対する黒レベルと白レベルとのそれぞれの設定値が入力され、記憶部２０に書き込まれて記憶される。 FIG. 6 is a flowchart illustrating a processing example of displaying a display screen image on the liquid crystal panel 21 performed by the image display device 1.
Step S1:
The image input unit 16 inputs a screen display image of each screen displayed on the display screen of the liquid crystal panel 21 from an external device.
Further, the setting values of the black level and the white level for each of the screens are input from the input means (not shown) by the user, and are written and stored in the storage unit 20.
　ステップＳ２：
　黒輝度算出部１１は、記憶部２０から画面の各々の黒レベル及び白レベルを読出し、それぞれの画面の黒輝度を算出し、各画面に対応させて記憶部２０に対して書き込んで記憶させる。 Step S2:
The black luminance calculation unit 11 reads the black level and the white level of each screen from the storage unit 20, calculates the black luminance of each screen, and writes and stores it in the storage unit 20 corresponding to each screen.
　ステップＳ３：
　最小黒輝度選択部１３は、記憶部２０を参照し、記憶されている各画面の黒輝度から最小の黒輝度を、最小黒輝度として選択して読み出し、オフセット量算出部１２に対して出力する。
　また、最大輝度選択部１４は、記憶部２０を参照し、記憶されている各画面の白レベルから最大の白レベルを、最大白レベルとして選択して読み出し、オフセット量算出部１２に対して出力する。
　そして、オフセット量算出部１２は、最小黒輝度と最大白レベルから画像オフセット補正量（オフセット量）を算出する。すなわち、オフセット量算出部１２は、画面の各々の黒輝度と最小黒輝度とから、それぞれの画面の差分輝度を求める。オフセット量算出部１２は、画面の各々の差分輝度を最大白レベルで除算し、除算結果を画面それぞれの画像オフセット補正量として算出する。オフセット量算出部１２は、画面の各々の画像画像オフセット補正量それぞれを画像オフセット部１７に対して出力する。 Step S3:
The minimum black luminance selection unit 13 refers to the storage unit 20, selects and reads out the minimum black luminance from the stored black luminances of the respective screens as the minimum black luminance, and outputs it to the offset amount calculation unit 12. .
Further, the maximum brightness selection unit 14 refers to the storage unit 20, selects and reads the maximum white level from the stored white levels of each screen as the maximum white level, and outputs it to the offset amount calculation unit 12. To do.
Then, the offset amount calculation unit 12 calculates an image offset correction amount (offset amount) from the minimum black luminance and the maximum white level. That is, the offset amount calculation unit 12 calculates the difference luminance of each screen from the black luminance and the minimum black luminance of each screen. The offset amount calculation unit 12 divides each difference luminance of the screen by the maximum white level, and calculates the division result as an image offset correction amount for each screen. The offset amount calculation unit 12 outputs each image image offset correction amount on the screen to the image offset unit 17.
　ステップＳ４：
　画像オフセット部１７は、供給された画像オフセット補正量に基づき、画面の各々の画面表示画像の黒レベルを上昇させるオフセット処理により、各画面の画面表示画像における階調の補正を行う。
　そして、画像合成部１８は、階調の補正が行なわれた画面表示画像の各々の合成を行ない、液晶パネル２１の表示画面に表示される表示画面画像を生成する。 Step S4:
Based on the supplied image offset correction amount, the image offset unit 17 performs gradation correction in the screen display image of each screen by an offset process that increases the black level of each screen display image on the screen.
Then, the image composition unit 18 performs composition of each of the screen display images on which the gradation has been corrected, and generates a display screen image to be displayed on the display screen of the liquid crystal panel 21.
　ステップＳ６：
　黒ムラ補正量計算部１５は、上記表示画面画像における画素の各々の階調及び液晶パネル２１の位置に対応して、それぞれの画素の階調及び位置に対応したムラ補正量を、記憶部２０のルックアップテーブルを参照して、ルックアップテーブルの補正値を用いた直線補完などを行なって求める。 Step S6:
The black unevenness correction amount calculation unit 15 stores the unevenness correction amount corresponding to the gradation and position of each pixel corresponding to the gradation of each pixel and the position of the liquid crystal panel 21 in the display screen image. Referring to the look-up table, a line interpolation using the correction value of the look-up table is performed.
　ステップＳ７：
　次に、黒ムラ補正量計算部１５は、最大白レベルを最小黒輝度により除算し、除算結果を目標コントラスト比とする。また、黒ムラ補正量計算部１５は、記憶部２０から調整時コントラスト比と無補正コントラスト比とを読み出す。
　そして、黒ムラ補正量計算部１５は、目標コントラスト比と、調整時コントラスト比及び無補正コントラスト比の各々とを比較する。このとき、黒ムラ補正量計算部１５は、目標コントラスト比が調整時コントラスト比以下であれば、処理をステップＳ８へ進める。また、黒ムラ補正量計算部１５は、目標コントラスト比が、調整時コントラスト比を超え、かつ無補正コントラスト比未満である場合、処理をステップＳ９へ進める。また、黒ムラ補正量計算部１５は、目標コントラスト比が無補正コントラスト比を超えている場合、処理をステップＳ１０へ進める。 Step S7:
Next, the black unevenness correction amount calculation unit 15 divides the maximum white level by the minimum black luminance and sets the division result as the target contrast ratio. Further, the black unevenness correction amount calculation unit 15 reads out the adjustment contrast ratio and the uncorrected contrast ratio from the storage unit 20.
Then, the black unevenness correction amount calculation unit 15 compares the target contrast ratio with each of the adjustment contrast ratio and the uncorrected contrast ratio. At this time, if the target contrast ratio is equal to or less than the adjustment contrast ratio, the black unevenness correction amount calculation unit 15 advances the process to step S8. If the target contrast ratio exceeds the adjustment contrast ratio and is less than the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 advances the process to step S9. If the target contrast ratio exceeds the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 advances the process to step S10.
　ステップＳ８：
　黒ムラ補正量計算部１５は、目標コントラスト比が調整時コントラスト比以下の場合、求めた階調値（ムラ補正量）を黒ムラ補正量として、黒ムラ補正部１９に対して出力する。 Step S8:
When the target contrast ratio is equal to or less than the adjustment contrast ratio, the black unevenness correction amount calculation unit 15 outputs the obtained gradation value (unevenness correction amount) to the black unevenness correction unit 19 as a black unevenness correction amount.
　ステップＳ９：
　黒ムラ補正量計算部１５は、目標コントラスト比が、調整時コントラスト比を超え、かつ無補正コントラスト比未満である場合、目標コントラスト比から調整時コントラスト比を減算した減算結果を、無補正コントラスト比から調整時コントラスト比から減算した減算結果により除算し、１から除算結果を減算した数値を調整量とする。そして、黒ムラ補正量計算部１５は、求めたムラ補正量に対して上記調整量を乗算し、この乗算結果を黒ムラ補正量として、黒ムラ補正部１９に対して出力する。 Step S9:
When the target contrast ratio exceeds the adjustment contrast ratio and is less than the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 obtains the subtraction result obtained by subtracting the adjustment contrast ratio from the target contrast ratio. Is divided by the subtraction result subtracted from the contrast ratio at the time of adjustment, and the numerical value obtained by subtracting the division result from 1 is used as the adjustment amount. Then, the black unevenness correction amount calculation unit 15 multiplies the obtained unevenness correction amount by the adjustment amount and outputs the multiplication result to the black unevenness correction unit 19 as a black unevenness correction amount.
　ステップＳ１０：
　黒ムラ補正量計算部１５は、目標コントラスト比が無補正コントラスト比を超えている場合、黒ムラ補正量を「０」として、黒ムラ補正部１９に対して出力する。 Step S10:
When the target contrast ratio exceeds the uncorrected contrast ratio, the black unevenness correction amount calculation unit 15 sets the black unevenness correction amount to “0” and outputs it to the black unevenness correction unit 19.
　ステップＳ１１：
　黒ムラ補正部１９は、表示画面画像の各画素の階調を、黒ムラ補正量計算部１５が求めた黒ムラ補正量に対応した階調値により補正する。 Step S11:
The black unevenness correction unit 19 corrects the gradation of each pixel of the display screen image with a gradation value corresponding to the black unevenness correction amount obtained by the black unevenness correction amount calculation unit 15.
　ステップＳ１２：
　液晶パネル２１は、黒ムラ補正部１９が補正した表示画面画像を、表示画面に表示する。 Step S12:
The liquid crystal panel 21 displays the display screen image corrected by the black unevenness correction unit 19 on the display screen.
　また、図１の画像表示装置における液晶パネルにおける表示ムラを補正する処理を、画像表示装置における制御機能を実現するためのコントロールを外部コンピュータシステムによって行てもよい。なお、ここでいう「コンピュータシステム」とは、ＯＳや周辺機器等のハードウェアを含むものとする。 Further, the processing for correcting the display unevenness in the liquid crystal panel in the image display device of FIG. 1 may be performed by an external computer system for realizing a control function in the image display device. Here, the “computer system” includes an OS and hardware such as peripheral devices.
　以上、この発明の実施形態を図面を参照して詳述してきたが、具体的な構成はこの実施形態に限られるものではなく、この発明の要旨を逸脱しない範囲の設計等も含まれる。 As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design and the like within the scope not departing from the gist of the present invention.
　上述した画像表示システムは、表示画像において数値的に正確な色再現が必要であり、かつユーザに対して負荷をかけることなく、簡便な操作により使い勝手が良いことが求められる液晶を用いたディスプレイに適用することができる。特に、グラフィックデザインや印刷所向け用途や、医用の画像診断向け用途など、正確な色再現が必要な用途に適している。 The above-described image display system is a display using a liquid crystal that requires numerically accurate color reproduction in a display image and is required to be easy to use by a simple operation without imposing a load on the user. Can be applied. In particular, it is suitable for applications that require accurate color reproduction, such as applications for graphic design and printing shops, and medical diagnostic imaging.
　１，１００…画像表示装置
　１１…黒輝度算出部
　１２…オフセット量算出部
　１３…最小黒輝度選択部
　１４…最大輝度選択部
　１５…黒ムラ補正量計算部
　１６…画像入力部
　１７…画像オフセット部
　１８…画像合成部
　１９…黒ムラ補正部
　２０…記憶部
　２１…液晶パネル DESCRIPTION OF SYMBOLS 1,100 ... Image display apparatus 11 ... Black brightness calculation part 12 ... Offset amount calculation part 13 ... Minimum black brightness selection part 14 ... Maximum brightness selection part 15 ... Black nonuniformity correction amount calculation part 16 ... Image input part 17 ... Image offset part 18 ... Image composition unit 19 ... Black unevenness correction unit 20 ... Storage unit 21 ... Liquid crystal panel

Claims (6)

  1. 　液晶パネルの表示画面に表示される複数の画面の黒ムラを補正して表示する画像表示装置であり、
    　前記画面毎に設定される黒レベルに基づくオフセット量により、前記画面それぞれの前記黒レベルを調整する画像オフセット部と、
    　前記黒レベルと前記画面毎に設定される白レベルとにより、前記表示画面全体におけるムラ補正を行なう黒ムラ補正部と
    　を備えることを特徴とする画像表示装置。     An image display device that corrects and displays black unevenness of a plurality of screens displayed on a display screen of a liquid crystal panel,
    An image offset unit for adjusting the black level of each of the screens by an offset amount based on the black level set for each of the screens;
    An image display device comprising: a black unevenness correction unit that performs unevenness correction on the entire display screen based on the black level and the white level set for each screen.
  2. 　前記画面毎に設定される黒レベル及び白レベルから、それぞれの前記画面の黒レベルの絶対値である黒輝度を算出する黒輝度計算部と、
    　前記画面の前記黒輝度における最小値を、前記画面の各々の前記黒輝度から減算し、前記画面それぞれの差分輝度を求め、当該差分輝度からオフセット量を求めるオフセット量算出部と
    　をさらに備える
    　ことを特徴とする請求項１に記載の画像表示装置。     A black luminance calculator for calculating black luminance, which is an absolute value of the black level of each screen, from a black level and a white level set for each screen;
    An offset amount calculation unit that subtracts the minimum value of the black luminance of the screen from the black luminance of each of the screens, obtains the difference luminance of each of the screens, and obtains an offset amount from the difference luminance. The image display device according to claim 1, wherein
  3. 　前記白レベルにおける最大値の最大白レベルを前記黒輝度の最小値で減算した目標コントラスト比に基づいて、前記オフセット量により調整された前記画面の画像が合成された表示画像の画素各々の階調を補正する黒ムラ補正量を求める黒ムラ補正量計算部
    　をさらに備える
    　ことを特徴とする請求項２に記載の画像表示装置。     The gradation of each pixel of the display image in which the screen image adjusted by the offset amount is synthesized based on the target contrast ratio obtained by subtracting the maximum white level of the maximum value in the white level by the minimum value of the black luminance. The image display apparatus according to claim 2, further comprising: a black unevenness correction amount calculation unit that obtains a black unevenness correction amount for correcting.
  4. 　前記黒輝度計算部が、
    　前記黒レベルと前記白レベルとを乗算し、乗算結果を前記黒輝度とする
    　ことを特徴とする請求項２及び請求項３に記載の画像表示装置。     The black luminance calculation unit is
    4. The image display device according to claim 2, wherein the black level is multiplied by the white level, and the multiplication result is set to the black luminance. 5.
  5. 　前記黒ムラ補正量計算部が、
    　前記白レベルにおける最大値の最大白レベルを前記黒輝度の最小値で減算した目標コントラスト比と、製造時における表示ムラ補正の調整を行なった際の調整時コントラスト比とを比較し、前記黒ムラ補正量を算出する
    　ことを特徴とする請求項３または請求項４に記載の表示装置。     The black unevenness correction amount calculation unit
    A target contrast ratio obtained by subtracting the maximum white level of the maximum value of the white level by the minimum value of the black luminance is compared with the contrast ratio at the time of adjustment of display unevenness correction at the time of manufacture, and the black unevenness is compared. The display device according to claim 3, wherein a correction amount is calculated.
  6. 　液晶パネルの表示画面に表示される複数の画面の黒ムラを補正して表示する画像表示方法であり、
    　画像オフセット部が、前記画面毎に設定される黒レベルに基づくオフセット量により、前記画面それぞれの前記黒レベルを調整する画像オフセット過程と、
    　黒ムラ補正部が、前記黒レベルと前記画面毎に設定される白レベルとにより、前記表示画面全体におけるムラ補正を行なう黒ムラ補正過程と
    　を含むことを特徴とする画像表示方法。     An image display method for correcting and displaying black unevenness of a plurality of screens displayed on a display screen of a liquid crystal panel,
    An image offset unit adjusts the black level of each screen by an offset amount based on the black level set for each screen; and
    An image display method comprising: a black unevenness correcting unit including a black unevenness correcting process for performing unevenness correction on the entire display screen based on the black level and the white level set for each screen.
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