1
`
`Inter Partes Review of RE 43,707
`IPR 2014-00778
`Exhibit 1019
`
`

`

`(19)
`
`JAPANESE PATENT OFFICE (JP)
`(12) Published Patent Application (A)
`(11)
` Patent Application Publication (Kokai) No. 2001-134252
`(P2001-134252A)
`(43) Publication Date: May 18, 2001
`
`
`(51) Int. Cl.7:
`
`
`
`G09G 5/00
`
`G02F 1/133
`
`G09G 3/20
`
`
`
` 3/36
`
`
`Classification
`Codes
`510
`505
`642
`680
`
`
`FI
`
`G09G 5/00
`G02F 1/133
` G09G 3/20
`
` 3/36
`
`Theme Codes
`
`(Reference)
`
`510 B 2H093
`505 5C006
`642 A 5C058
`680 C 5C060
`
` 5C080
`
`Number of Claims: 16
`Request for Examination: Not requested
`OL (Total of 14 pages [in original]) Continued on last page
`Patent App. No. H11-311781
`November 2, 1999
`000004112
`Nikon Corp.
`3-2-3 Marunouchi, Chiyoda-ku, Tokyo
`Hirofumi Hidari
`Nikon Corp.
`3-2-3 Marunouchi, Chiyoda-ku, Tokyo
`Keiichi Nitta
`Nikon Corp.
`3-2-3 Marunouchi, Chiyoda-ku, Tokyo
`100084412
`Fuyuki Nagai, Patent Attorney
`
`(21) Application No.:
`(22) Filing Date:
`(71) Applicant:
`
`
`(72) Inventor:
`
`
`(72) Inventor:
`
`
`(74) Agent:
`
`
`Continued on last page
`Data Processing Device, Image Display Device, and
`Image Pickup Device
`
`(54)
`
`[Title of the Invention]
`
`[Abstract]
`(57)
`[Purpose]
`To provide a data processing device, an image display device, and an
`image pickup device capable of suppressing a decrease in the image quality of projected
`images, without requiring a large amount of effort or time.
`[Solution]
`A data processing device 200 sequentially inputs, via an image pickup
`device 52, discontinuous gradation test pattern images displayed by projection on a
`screen 53 by an image display device 51. The data processing device 200 samples only
`
`2
`
`

`

`the image data of parts of points e, f, g, and h in the screen 53, and gradation correction
`values corresponding to all the gradations of points e, f, g, and h are calculated by
`interpolation calculation from the sampling results. Subsequently, the data processing
`device 200 calculates the gradation correction values for parts other than points e, f, g,
`and h by interpolation calculation based on the gradation correction values of points e, f,
`g, and h.
`
`
`
`[FIG. 1]
`
`[Claims]
`[Claim 1]
`
`A data processing device, comprising:
`
`a sample data extraction means for, from data sampled at a first sampling interval,
`extracting sample data at a second sampling interval greater than the first sampling
`interval,
`
`a correction data generating means for generating correction data having a third
`sampling interval that is greater than the first sampling interval and smaller than the
`second sampling interval from the sampling data using interpolation processing, and
`
`2
`
`3
`
`

`

`a correction means for correcting pre-correction data based on the correction data,
`
`and generating post-correction data.
`[Claim 2]
`
`The data processing device according to claim 1, wherein
`
`the correction data is stored in lookup tables that define the relationship of values
`of the post-correction data with values of the pre-correction data.
`[Claim 3]
`
`An image display device for displaying images based on input data, the device
`comprising:
`
`the data processing device according to claim 1 or 2, and
`
`a display signal output means for outputting display signals for displaying images
`based on the post-correction data generated by the correction means.
`[Claim 4]
`
`An image pickup device comprising a photoelectric conversion device for
`performing photoelectric conversion of a photographic subject formed using an imaging
`lens and outputting image signals, the image pickup device comprising:
`
`the data processing device according to claim 1 or 2, wherein
`the correction means corrects the pre-correction data which is image data
`
`generated based on the image signals output from the photoelectric conversion device and
`generates the post-correction data.
`[Claim 5]
`
`The image display device according to claim 3, further comprising
`
`a test pattern generating means for generating test pattern data for displaying a
`plurality of predetermined types of test pattern images, and
`
`a display image monitoring means for inputting at least a portion of display
`images based on the test pattern data, and outputting image data, wherein
`
`the sample data extraction means extracts the sample data from image data output
`from the display image monitoring means.
`[Claim 6]
`
`The image display device according to claim 5, wherein
`
`3
`
`4
`
`

`

`when a display gradation count of the images is M, the number of types of test
`
`patterns generated by the test pattern generating means is less than M.
`[Claim 7]
`
`The image display device according to claim 5 or 6, wherein
`
`the correction data generating means generates the correction data so as to
`suppress at least any one of shading and color unevenness that occur with displayed
`images.
`[Claim 8]
`
`The image display device according to any one of claims 5 through 7, wherein
`
`the display image monitoring means is provided as an integral unit with the image
`display device, or as an integral unit with an image display screen.
`[Claim 9]
`
`The image display device according to claim 6, wherein
`
`a correction signal corresponding to a test pattern not generated with the test
`pattern generating means is found by interpolation from the results obtained using test
`patterns of a count of less than M.
`[Claim 10]
`
`An image pickup device, comprising
`
`the data processing device according to claim 1 or 2, and
`
`a photoelectric conversion means for performing image pickup of at least a part of
`an image based on a plurality of types of test pattern data and outputting image data,
`wherein
`
`the sample data extraction means extracts the sample data from image data output
`from the photoelectric conversion means.
`[Claim 11]
`
`The image pickup device according to claim 10, wherein
`
`when the image display gradation count is M, the number of types of the test
`patterns is less than M.
`[Claim 12]
`
`The image pickup device according to claim 11, wherein
`
`4
`
`5
`
`

`

`a correction signal corresponding to a test pattern that has not undergone image
`
`pickup is found by interpolation from the results obtained using the less than M number
`of test patterns.
`[Claim 13]
`
`A data processing device, comprising:
`
`a sample data extraction means for extracting, from data for which image signals
`were sampled at a first sampling interval, sample data at a second sampling interval
`greater than the first sampling interval,
`
`a correction data generating means for generating correction data having a third
`sampling interval that is greater than the first sampling interval and smaller than the
`second sampling interval from the sample data using interpolation processing, and
`
`a correction means for correcting the image signals based on the correction data,
`and generating corrected image signals.
`[Claim 14]
`
`An image display device, comprising:
`
`a sample data extraction means for extracting, from data for which image signals
`were sampled at a first sampling interval, sample data at a second sampling interval
`greater than the first sampling interval,
`
`a correction data generating means for generating correction data having a third
`sampling interval greater than the first sampling interval and smaller than the second
`sampling interval from the sample data using interpolation processing,
`
`a correction means for correcting the image signals based on the correction data,
`and outputting corrected image signals, and
`
`a display means for displaying images based on the image signals corrected and
`output by the correction means.
`[Claim 15]
`
`An image pickup device comprising:
`
`a photoelectric conversion means for performing photoelectric conversion of a
`photographic subject and outputting image signals,
`
`5
`
`6
`
`

`

`a sample data extraction means for extracting, from data for which the image
`
`signals were sampled at a first sampling interval, sample data at a second sampling
`interval greater than the first sampling interval,
`
`a correction data generating means for generating correction data having a third
`sampling interval greater than the first sampling interval and smaller than the second
`sampling interval from the sample data using interpolation processing, and
`
`a correction means for correcting the image signals based on the correction data,
`and generating corrected image signals.
`[Claim 16]
`
`An image pickup device, comprising:
`
`a photoelectric conversion means for performing image pickup of at least a
`portion of an image based on a plurality of types of test patterns, and outputting image
`signals,
`
`a sample data extraction means for extracting, from data for which the image
`signals were sampled at a first sampling interval, sample data at a second sampling
`interval greater than the first sampling interval,
`
`a correction data generating means for generating correction data having a third
`sampling interval greater than the first sampling interval and smaller than the second
`sampling interval from the sample data using interpolation processing, and
`
`a correction means for correcting the image signals based on the correction data
`and generating corrected image signals.
`[Detailed Description of the Invention]
`[0001]
`[Technical Field of the Invention]
`
`The present invention relates to a data processing device, an image display device,
`and an image pickup device, and more specifically relates to a data processing device, an
`image display device, and an image pickup device that generate correction data
`corresponding to a relatively fine sampling interval using interpolation based on data
`sampled at a relatively rough sampling interval, and correct input data based on the
`correction data.
`[0002]
`
`6
`
`7
`
`

`

`[Prior Art]
`
`As a projection type image display device capable of correcting brightness
`unevenness (hereafter in this specification, a projection type image display device is
`simply referred to as a "display device"), there is the item disclosed in Unexamined
`Patent Publication No. H08-223519. With this display device, an image displayed on a
`projection screen is photographed using an image pickup camera. At this time, the screen
`is divided into a plurality of grid areas and photographed, and the brightness on the
`projected screen is found for each area. Subsequently, based on the found brightness of
`each area, a brightness correction value corresponding to each area is found. Memory is
`provided in the display device, and a brightness correction value corresponding to each
`divided area of the projection screen is recorded in the memory.
`[0003]
`
`When projection display is performed with the display device noted above, the
`input video signals input to this display device are synchronized, and address values
`corresponding to the divided areas of the projection screen are set with an address
`counter. The brightness correction values are read in sequence from the memory
`corresponding to this address value. The read brightness correction values are converted
`to analog values by a D/A converter circuit to obtain an analog correction value, and by
`doing arithmetic processing of this analog correction value and the input video signal,
`brightness unevenness on the projection screen is corrected.
`[0004]
`[Problems the Invention Attempts to Solve]
`
`For example, with a device using a dichroic mirror such as represented by a three-
`tube type or three-plate type electronic camera or projection type display device, the
`spectral characteristics change according to the angle of incidence of light made
`incidental on the dichroic mirror. By this phenomenon of spectral characteristics
`changing according to the difference in the angle of incidence, shading occurs. By this
`shading, brightness unevenness occurs on the projected screen. When the changes in
`spectral characteristics noted above that occurs due to a difference in the angle of
`incidence differs for each colored light, the color balance changes according to the
`location on the projected screen, and color unevenness occurs. When color unevenness
`
`7
`
`8
`
`

`

`occurs, for example regardless of whether an achromatic image signal is input, coloring
`occurs according to the location on the screen. When an attempt is made to perform color
`unevenness correction in analog form as described previously, there are cases when it is
`not possible to do correction due to variation of the characteristics of the components
`themselves constituting the correction circuit, or to variation of the product performance.
`[0005]
`
`In contrast to this, it is possible to perform digital correction for correction of the
`color unevenness or brightness unevenness described above. In this case, with the kind of
`method described previously, it is possible to apply a method of dividing the projected
`screen into a plurality of areas on a grid and take a photograph, to find the brightness on
`the projection screen for each area, and to find a brightness correction value for each
`area. Then, instead of the analog correction described above, the input video signals are
`digitally corrected using the correction values read from memory described previously.
`[0006]
`
`However, when the number of divisions is low when dividing the projected screen
`into a plurality of areas on a grid and taking a photograph, the input video signals
`corresponding to the interior of a certain division area may be corrected using the same
`correction values, so correction is not performed at a fine level. In other words, when
`focus is placed on each individual pixel constituting the projected screen, complete
`correction is not possible and there are remaining errors, specifically, residual errors.
`These residual errors may suddenly change across a boundary of adjacent division areas.
`In that case, due to the sudden change in residual errors, correction is not performed, and
`there is also a sudden change across the boundary for residual brightness unevenness or
`color unevenness, causing a decrease in the image quality of the projected image.
`[0007]
`
`It is also possible to make corrections for each pixel of the displayed image in
`order to suppress sudden changes in brightness unevenness or color unevenness that
`occur between division areas. However, working in this way, there is the problem that a
`great deal of effort and time is required to obtain correction values, and the memory
`space required for storing the correction values is huge.
`[0008]
`
`8
`
`9
`
`

`

`An object of the present invention is to provide a data processing device, an
`
`image display device, and an image pickup device capable of suppressing a decrease in
`image quality of the projected image while requiring only a small memory capacity for
`storing the correction values and not requiring a great deal of effort and time.
`[0009]
`[Means to Solve the Problems]
`
`We will describe the invention below in correspondence to FIG. 1 and FIG. 2
`which show an embodiment.
`(1)
`The data processing device according to the invention of claim 1 achieves the
`object described above by comprising a sample data extraction means 84 for extracting,
`from data sampled at a first sampling interval, sample data at a second sampling interval
`greater than the first sampling interval, a correction data generating means 84 for
`generating correction data having a third sampling interval that is greater than the first
`sampling interval and smaller than the second sampling interval from the sampling data
`using interpolation processing, and correction means 77, 78, and 79 for correcting the
`pre-correction data based on the correction data, and generating post-correction data.
`(2)
`The data processing device according to the invention of claim 2 stores the
`correction data in lookup tables that define the relationship of values of the post-
`correction data to values of the pre-correction data.
`(3)
`The invention according to claim 3 is applied to an image display device for
`displaying images based on input data. Also, the data processing device according to
`claim 1 or 2, and a display signal output means 80 for outputting display signals for
`displaying images based on the post-correction data generated by the correction means
`77, 78, and 79, are provided.
`(4)
`The invention according to claim 4 is applied to an image pickup device having a
`photoelectric conversion device for doing photoelectric conversion of a photographic
`subject formed using an imaging lens and outputting image signals. The data processing
`device according to claim 1 or 2 is also provided, wherein the correction means 77, 78,
`and 79 correct the pre-correction data which is the image data generated based on the
`image signals output from the photoelectric conversion device and generate the post-
`correction data.
`
`9
`
`10
`
`

`

`The image display device according to the invention of claim 5 further has a test
`(5)
`pattern generating means 82 for generating test pattern data for displaying a plurality of
`predetermined types of test pattern images, and a display image monitoring means 52 for
`inputting at least a portion of the display image based on the test pattern data, and
`outputting image data, wherein the sample data extraction means 84 extracts the sample
`data from image data output from the display image monitoring means 52.
`(6) With the image display device according to the invention in claim 6, when the
`image display gradation count is M, the number of types of test patterns generated by the
`test pattern generating means 82 is less than M.
`(7) With the image display device according to the invention of claim 7, the
`correction data generating means 84 generates the correction data so as to suppress at
`least one of shading and color unevenness that occur with displayed images.
`(8) With the image display device according to the invention of claim 8, the display
`image monitoring means 52 is provided as an integral unit with the image display device
`51, or as an integral unit with an image display screen 53.
`(9) With the image display device according to the invention of claim 9, a correction
`signal corresponding to a test pattern not generated with the test pattern generating means
`82 is found by interpolation from the results obtained using test patterns of a count of less
`than M.
`(10) The image pickup device according to the invention of claim 10 has the data
`processing device according to claim 1 or 2, and a photoelectric conversion means 52 for
`performing image pickup of at least a part of an image based on a plurality of types of
`test pattern data and outputting image data, wherein the sample data extraction means 84
`extracts the sample data from image data output from the photoelectric conversion means
`52.
`(11) With the image pickup device according to the invention of claim 11, when the
`image display gradation count is M, the number of types of the test patterns is less than
`M.
`(12) With the image pickup device according to the invention of claim 12, a correction
`signal corresponding to a test pattern that has not undergone image pickup is found by
`interpolation from the results obtained using the less than M number of test patterns.
`
`10
`
`11
`
`

`

`(13) The data processing device according to the invention of claim 13 has a sample
`data extraction means 84 for extracting, from data for which image signals were sampled
`at a first sampling interval, sample data at a second sampling interval greater than the first
`sampling interval, a correction data generating means 84 for generating correction data
`having a third sampling interval that is greater than the first sampling interval and smaller
`than the second sampling interval from the sample data using interpolation processing,
`and correction means 77, 78, and 79 for correcting the image signals based on the
`correction data, and generating corrected image signals.
`(14) The image display device according to the invention of claim 14 has a sample
`data extraction means 84 for extracting, from data for which image signals were sampled
`at a first sampling interval, sample data at a second sampling interval greater than the first
`sampling interval, a correction data generating means 84 for generating correction data
`having a third sampling interval greater than the first sampling interval and smaller than
`the second sampling interval from the sample data using interpolation processing,
`correction means 77, 78, and 79 for correcting the image signals based on the correction
`data, and outputting corrected image signals, and a display means 80 for displaying
`images based on the image signals corrected and output by the correction means 84.
`(15) The image pickup device according to the invention of claim 15 has a
`photoelectric conversion means 52 for performing photoelectric conversion of a
`photographic subject and outputting image signals, a sample data extraction means 84 for
`extracting sample data at a second sampling interval greater than a first sampling interval
`from data for which the image signals were sampled at the first sampling interval, a
`correction data generating means 84 for generating correction data having a third
`sampling interval greater than the first sampling interval and smaller than the second
`sampling interval from the sampling data using interpolation processing, and correction
`means 77, 78, and 79 for correcting the image signals based on the correction data, and
`generating corrected image signals.
`(16) The image pickup device according to the invention of claim 16 has a
`photoelectric conversion means 52 for performing image pickup of at least a portion of an
`image based on a plurality of types of test patterns, and outputting image signals, a
`sample data extraction means 84 for extracting, from data for which the image signals
`
`11
`
`12
`
`

`

`were sampled at a first sampling interval, sample data at a second sampling interval
`greater than the first sampling interval, a correction data generating means 84 for
`generating correction data having a third sampling interval greater than the first sampling
`interval and smaller than the second sampling interval from the sample data using
`interpolation processing, and correction means 77, 78, and 79 for correcting the image
`signals based on the correction data and generating corrected image signals.
`[0010]
`
`With the items of the means for addressing the problems noted above describing
`the constitution of the present invention, drawings of modes for embodying the invention
`have been used to make it easy to understand the present invention, but this does not limit
`the modes for embodying the present invention.
`[0011]
`[Embodiments of the Invention]
`
`FIG. 1 is a drawing showing the schematic constitution of the image display
`device equipped with the data processing device of a mode for embodying the present
`invention. An image display device 51 is equipped with an image pickup device 52 and a
`data processing device 200. The image display device 51 is for example a projection-type
`liquid crystal projector, and is equipped with a liquid crystal light bulb for generating an
`image based on video signals input from an external device, a light source for
`illuminating an image generated by the liquid crystal light bulb, a projection lens for
`projecting onto the screen 53 the image illuminated by the light source, and the like. The
`image display device 51 is further equipped with the image pickup device 52 for
`inputting (photographing) the image displayed on the screen 53, and the data processing
`device 200 for processing the image signals output from the image pickup device 52. The
`image pickup device 52 and the data processing device 200 are incorporated as a single
`unit with the image display device 51.
`[0012]
`
`The constitution is such that power is supplied from the power supply of the
`image display device 51 main unit to the image pickup device 52 and the data processing
`device 200. A calibration operation setting switch (not illustrated) is provided on the
`image display device 51. By the operator operating this switch and the calibration mode
`
`12
`
`13
`
`

`

`being set, power is supplied to the image pickup device 52 and the data processing device
`200. Meanwhile, in a normal use state, specifically, a state for which an image based on
`the video signal input from an external device is projected on the screen 53, power is not
`supplied to the image pickup device 52 and the data processing device 200. Therefore,
`wasteful consumption of power is inhibited. We will later give an explanation regarding
`the four points e, f, g, and h displayed with X-marks on the screen 53.
`[0013]
`
`FIG. 2 is a block diagram schematically showing the internal configuration of the
`image display device 51. On terminals 71, 72, and 73, the analog R, G, and B image
`signals are respectively input for displaying the image of the screen 53, and are converted
`to digital image signals by A/D converters 74, 75, and 76. The timing of the A/D
`conversion by the A/D converters 74, 75, and 76 is controlled by timing signals output
`from an address supply circuit 87.
`[0014]
`
`The address supply circuit 87 generates the previously described A/D conversion
`timing signals and address signals from horizontal synchronization signals input to a
`terminal 85 and vertical synchronization signals input to a terminal 86. The address
`signals generated by the address supply circuit 87 are input to lookup tables (hereafter in
`this specification, lookup tables are called "LUTs") 77, 78, and 79.
`[0015]
`
`We will give a detailed description of the internal configuration of the address
`supply circuit 87 while referring to FIG. 3 which schematically shows the internal
`configuration of the address supply circuit 87. The horizontal synchronization signals
`input from the terminal 85 are input to a phase comparator 91. Signals output from a TC
`terminal of a horizontal counter 93 described later are input to the other input of the phase
`comparator 91. Analog voltage signals according to the phase difference of two signals
`input to the phase comparator 91 are input to a VCO 92 from the phase comparator 91.
`[0016]
`
`The VCO 92 outputs pulse signals of frequencies according to the input voltage
`from the phase comparator 91. The pulse signals output from the VCO 92 are input to
`A/D converters 74, 75, and 76, and to a clock terminal (CK) of the horizontal counter 93.
`
`13
`
`14
`
`

`

`The horizontal counter 93 is an N-decimal counter, and when N pulses are input from the
`clock terminal, one pulse is output from the terminal count terminal (TC). The signals
`output from the terminal count terminal are input to the phase comparator 91, and as
`described above, undergo a phase comparison with the horizontal synchronization signals
`input from the terminal 85.
`[0017]
`
`The horizontal counter 93 counts the number of pulse signals output from the
`VCO 92, and outputs count values from an output terminal (Qn). The signals output from
`the horizontal counter 93 are parallel signals, and the parallel signals become horizontal
`address signals input to LUTs 77, 78, and 79. The aforementioned N is set according to
`the display resolution of the horizontal direction of the image display device 51, and can
`also be fixed according to the specification of the image display device 51, and if this
`image display device 51 is a so-called multi-scan type, setting changes can be performed
`automatically according to the input video signals, or manually.
`[0018]
`
`The pulse signals output from the terminal counter terminal (TC) are then input to
`a vertical counter 94 clock terminal (CK). The vertical synchronization signals input from
`the terminal 86 are input to the vertical counter 94 reset terminal (RST). The vertical
`counter 94 counts the number of pulse signals input from the horizontal counter 93, and a
`count value is output from the output terminal (Qn). This count value is reset when the
`vertical synchronization signal is input to the reset terminal. The output signals of the
`vertical counter 94 are parallel signals, the same as with the output signals of the
`horizontal counter 93, and become vertical address signals input to the LUTs 77, 78, and
`79.
`[0019]
`
`Referring to FIG. 2 again, we will describe the internal configuration of the image
`display device 51. The outputs of the LUTs 77, 78, and 79 are respectively connected to
`terminal A of a switch 81. The output of a test pattern generating circuit 82 is connected
`to terminal B of the switch 81. When the switch 81 is connected to the terminal A, the
`image data output from the LUTs 77, 78, and 79 is input to an LCD driver 80. The LCD
`driver 80 outputs drive signals such as for a liquid crystal light bulb or the like (not
`
`14
`
`15
`
`

`

`illustrated) based on the input image data. Later, we will give a detailed description of the
`test pattern generating circuit 82.
`[0020]
`
`The data processing device 200 is constituted from a CPU 84, a working memory
`83 and the like. The CPU 84 issues a test pattern generating instruction signal to the test
`pattern generating circuit 82 during the calibration operation described in detail later, and
`switches the switch 81 to terminal B. When this happens, a designated test pattern is
`projected and displayed on the screen 53 (FIG. 1). At this time, the image pickup device
`52 inputs, specifically, photographs, the image projected on the screen 53, and outputs an
`image signal to the working memory 83. The CPU 84 processes the image signal
`described above stored in the working memory 83 as described later, and calculates
`correction values for correcting at least one of shading and color unevenness and outputs
`the correction values to the LUTs 77, 78, and 79. The LUTs 77, 78, and 79 store these
`correction values.
`[0021]
`
`With the image display device 51 constituted as described above, we will describe
`in sequence the calibration operation performed by the data processing device 200 that
`this image display device 51 has, and the image display operation performed by the
`image display device 51. To simplify the description, hereafter, the display resolution of
`the image display device 51 will be 6 pixels each for both the horizontal direction and the
`vertical direction. Also, the gradations of each color R, G, and B is 3 bits, specifically, 8
`gradations of 0 (darkest) to 7 (brightest), but the present invention is not limited to these
`values.
`[0022]
`Calibration Operation
`
`FIG. 4 is a flow chart for describing the calibration procedure executed by the
`CPU 84 incorporated in the data processing device 200. Hereinbelow, we will describe
`the calibration procedure executed by the CPU 84 while referring to FIG. 1 through FIG.
`7.
`[0023]
`
`15
`
`16
`
`

`

`At step S101, the CPU 84 switches the switch 81 to terminal B. Regarding this
`
`switching of the switch 81, instead of having the CPU 84 perform the switching
`automatically, it is also possible to have the operator perform the switching manually.
`[0024]
`
`At step S102, the CPU 84 issues a test pattern generating instruction signal to the
`test pattern generating circuit 82. The test pattern generating circuit 82 generates a test
`pattern described hereafter in response to the instruction signal output from the CPU 84.
`When this happens, a designated test pattern is displayed on the screen 53.
`[0025]
`
`With this embodiment, the test pattern projected on the screen 53 is a neutral gray
`uniform pattern for which R, G, and B are the same gradation values. At this time,
`according to the gradation values being changed to 0, 4, and 7, the test pattern projected
`on the screen 53 changes to black, gray, and white. However, the image projected on the
`screen 53 has not undergone a correction. Because of this, variation of the γ
`characteristics (display image concentration characteristics in relation to the input
`signals) of the liquid crystal light bulb of each color R, G, and B, or shading or the like is
`affected. As a result, brightness unevenness or coloring (color unevenness) occurs where
`a uniform pattern originally having neutral colors is supposed to be displayed on the
`screen 53 depending on the locations on the screen 53.
`[0026]
`
`The test pattern image projected and displayed on the screen 53 is input by the
`image pickup device 52, and the image data is output from the image pickup devi