(19) Japan Patent Office
`(JP)
`
`(12) Japanese Unexamined Patent
`Application Publication (A)
`
`(11) Japanese Unexamined Patent
`Application Publication Number
`H9-198019
`
`(43) Publication date July 31,1997
`
`(51) Int. CL®
`GO09G 5/10
`5/00
`
`HO4N 1/407
`
`Identification codes
`
`550
`
`JPO file numbers
`9377-5H
`9377-5H
`9377-5H
`
`FI
`GO09G 5/10
`5/00
`
`HO4N 1/407
`
`B
`X
`550 C
`101
`~2£
`
`Technical indications
`
`Request for examination Not yet requested Numberof claims 4 OL (Total of 4 pages)
`
`(21) Application
`number
`
`(22) Date of application
`
`Japanese Patent
`Application
`H8-5867
`January17, 1996
`
`(71) Applicant
`
`000005201
`FUJI PHOTO FILM CO., LTD.
`210 Nakanuma, Minami-ashigara, Kanagawa-
`ken
`
`(72) Inventor
`
`(74) Agent
`
`OGAWA EIJI
`c/o FUJI PHOTO FILM CO., LTD
`798 Miyanodai, Kaisei-machi, Ashigarakami-
`gun, Kanagawa-ken
`Patent attorney Yanagida Masashi (and | other)
`
`
`
`(54) (TITLE OF THE INVENTION) IMAGE DISPLAY METHOD AND APPARATUS
`
`(57) (ABSTRACT)
`(PROBLEM) In displaying an image on a light emitting display means such as a CRT, shading resulting from
`variation in the brightness of the CRT is corrected to accurately display an image.
`(MEANS FOR SOLVING) A CRT 2 is divided into three regions 2A, 2B, 2C, and the brightnesses of the respective
`regions 2A, 2B, 2C are detected by a detecting means 3. The detection result is compared at a comparing means4,
`and correction is performed so that the brightnesses of the images to be displayed at the respective regions 2A, 2B,
`2C are made approximately equivalent by means of a shading correcting means | based on this comparison result.
`The corrected image signals S1, S2, $3 are subject to gradation correction by a gradation correcting means 5 and are
`respectively displayed at the respective regions 2A, 2B, 2C of the CRT 2.
`
`

`

`Japanese Unexamined Patent Application Publication H9-198019
`(2)
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`Japanese Unexamined Patent Application Publication H9-198019
`3)
`
`(SCOPE OF PATENT CLAIMS)
`(CLAIM1) An image display method that displays an image signal as visible light on a light emitting display means;
`characterized in that
`the brightness of each of the portions of the light emitting display meansts detected, and,
`based on said detection result, shading correction is performed on the image signal so that the brightness of each of
`the portions of the light emitting display means becomes approximately equivalent.
`(CLAIM 2) An image display method according to Claim 1; characterized in that the light emitting display meansis
`divided into a plurality of regions,
`the brightnesses of said respective regions are detected, and the shading
`correction is performed for each of said respective regions.
`(CLAIM 3) An image display apparatus that displays an image signal as visible light on a light emitting display
`means; characterized in that it comprises
`a brightness detecting means, which detects the brightness of each of the portions of the light emitting
`display means, and
`a shading correcting means, which, based on said detection result, performs shading correction on the
`image signal so that
`the brightness of each of the portions of the light emitting display means becomes
`approximately equivalent.
`(CLAIM4) An image display apparatus according to Claim 3; characterized in that the brightness detecting meansis
`a means that divides the light emitting display means into a plurality of regions to detect the brightness of each of
`said respective regions, and the shading correcting means is a means that performs the shading correction for each of
`said respective regions.
`(DETAILED DESCRIPTION OF THE INVENTION)
`{O001}
`(TECHNICAL FIELD OF THE INVENTION)
`The present invention relates to an image display method and apparatus that display an image on a light
`emitting display means such as a CRT and particularly relates to an image display method and apparatus that
`perform shading correction on an image signal to performdisplay on a light emitting display means.
`{0002}
`(PRIOR ART)
`Conventionally, in the case in which an imageis to be displayed on a light emitting display means suchas a
`CRT, a gradation conversion table, which makes the gradation characteristic (the relationship between the image
`signal value and the logarithmic value of the brightness on the light emitting display means) of the light emitting
`display means linear, is comprised, and an image is displayed after gradation conversion has been performed on an
`image signal according to this gradation conversiontable.
`[0003]
`(PROBLEMS TO BE SOLVED BY THE INVENTION)
`However,
`in a light emitting display means such as that discussed above, due to such factors as
`irregularities of the fluorescent material layer, variation in the curvature of the tube surface, and electron gun output
`irregularity, shading occurs, and the brightmess unfortunately becomesirregular at each of the portions on the light
`emitting display means. For example, in the CRT, in general, the brightness is higher the nearer the center of the
`tube surface, and the brightness is lower than nearer the periphery. When the brightness varies in this way, it
`becomes impossible to correctly display image information that the image signal carries on the light emitting display
`means. Particularly in a case such as one in which the light emitung display means is divided into a phuirality of
`regions, and an image for medical use is displayed in the respective regions to perform a comparative diagnosis,
`whenthere is variation in brightness, there is concern that it will not be possible to perform an accurate comparison
`and that misdiagnosis will unfortunately occur.
`{0004}
`
`The present invention takes the aforementioned circumstances into account, and its purpose is to provide an
`image display method and apparatus that are able to eliminate variation in brightess resulting from shading of the
`light emitting display means.
`{0005}
`(MEANS TO SOLVE PROBLEMS)
`The image display method and apparatus of the present invention are such that an image display method
`that displays an image signal as a visible image on a light emitting display means is characterized im that the
`brightness of each of the portions of the light emitting display means is detected, and shading correction is
`performed on the image signa! based on said detection result so that the brightness of each of the portions of the
`light emitting display means becomes approximately equivalent.
`{0006}
`
`

`

`Japanese Unexamined Patent Application Publication H9-198019
`(4)
`
`In addition, in the image display method and apparatus,it is preferable that the light emitting display means
`is divided into a plurality of regions, the brightness of each of said respective regions be detected, and the shading
`correction to be performed for each of said respective regions.
`{0007|
`(EFFECTS OF THE INVENTION)
`The image display method and apparatus according to the present invention detect the brightness of each of
`the portions of a light emitting display means such as a CRT and perform shading correction on an image signal
`based on these detected brightnesses so that the brightness of each of these portions becomes equivalent, so even if
`there is variation in the brightness of each of the portions of the light emitting display means, this variation is
`corrected. Therefore, it is possible to display an accurate tmage that has no effects of shading on the light emitting
`display means.
`[O008}
`
`In addition, in a case in whichthe light emitting display means is divided into a plurality of regions, and a
`plurality of images are displayed at the respective regions for the purpose of a comparative diagnosis, by detecting
`the brightness of each of the respective regions to perform shading correction,it is possible to correct variation of
`the brightness in each of the respective regions to display images using a brightness that is approximately mutually
`equivalent in the respective regions. Therefore, in the case in which a plurality of images are displayed on a light
`emitting display means to perform comparative diagnosis,
`it
`is possible to perform an accurate comparative
`diagnosis, and, throughthis, it is possible to prevent misdiagnosis resulting fromthe effects of shading.
`{0009}
`(EMBODIMENTSOF THE INVENTION)
`Embodiments of the present invention will be described while referring to the following drawings.
`
`{OO10}
`
`is a block diagram that shows an embodiment of an image display apparatus resulting from the
`1
`Fig.
`present invention. The illustrated display apparatus is a display apparatus that displays a plurality of images for
`medical use on one light emitting display means, and it comprises a shading correcting means |, which performs
`shading correction on image signals $1, $2, S3 as discussed below, a gradation correcting means 5, which performs
`gradation correction of the image signals S1, $2, $3 on which shading correction has been performed by the shading
`correcting means 1, a CRT 2 as an example of a light emitting display means that, based on the image signals S1,
`$2, S3 that have been gradation corrected by the gradation correcting means 5, displays images carried by these
`image signals S1, $2, $3 in the respective three divided regions 2A, 2B, 2C as shownin Fig. 1, a detecting means 3
`such as a luminance meter, which detects the brightnesses of the respective regions 2A, 2B, 2C of the CRT 2, anda
`comparing means 4, which compares the brightnesses of the respective regions 2A, 2B, 2C of the CRT2. It is also
`such that, at the shading correcting means 1, shading correction of the image signals S1, $2, $3 is performed based
`on the comparison results of the comparing means 4 so that the brightnesses of the respective regions 2A, 2B, 2C
`become approximately equivalent.
`{Oo
`
`Next, the action of an image display apparatus according to the present invention will be described. First,
`the brightnesses of the respective regions 2A, 2B, 2C of the CRT 2 are detected by the detecting means 3. This
`detection of the brightesses is performed in the following way. First, in a state in which an image with a uniform
`pixel value has been displayed on the CRT 2, the brightness L1, L2, L3 of each of the three divided regions 2A, 2B,
`2C is detected by the detecting means 3. This detection of the brightnesses L1, L2, L3 is performed by detecting,for
`example, the average level of the brightnesses of the respective regions 2A, 2B, 2C. Whenthe brightnesses LI, L2,
`L3 of the respective regions 2A, 2B, 2C are detected in this way, a comparison of these brightnesses L1, L2, L3 is
`performed at the comparing means 4. Then the comparison result from the comparing means 4 is input to the
`shading correcting means 1.
`{0012}
`
`At the shading correcting means 1, correction of the respective image signals $1, $2, S3 is performed based
`on the comparison result from the comparing means 4 so that the brightnesses of the images to be displayed in the
`respective regions 2A, 2B, 2C become approximately equivalent. This correction is performed so that, based on the
`comparison result, the brightness levels of other regions match that of the region in which the brightness level is
`lowest. For example, in the case in which brightness L3 of region 2C from amongbrightnesses L1, L2 and L3 of the
`respective regions 2A, 2B, 2C shown in Fig. 2 had the lowest level, correction of image signals SI and S2 is
`performed so that brightnesses LI and L2 of the other regions 2A, 2B match brightness L3 of region 2C.
`Specifically, correction is performed so that the levels of the respective image signals SI and S2 are reduced so that
`the levels of image signals Si and S2 to be respectively displayed in regions 2A and 2B become approximately
`equivalent to the brightness level of image signal S3 to be displayed in region 2C. Then, image signals $1, $2 and
`
`

`

`Japanese Unexamined Patent Application Publication H9-198019
`(5)
`
`$3, on which shading correction has been performed in this way, are subject to gradation correction at the gradation
`cofrecting means 5 and are displayed as visible imagesat the respective regions 2A, 2B, 2C of the CRT 2.
`{0013}
`
`In this way, in the case in which respectively different images are displayed in the divided regions 2A, 2B,
`2C of the CRT 2 to perform comparative diagnosis, by detecting the brightness L1, L2, L3 of each of the respective
`regions 2A, 2B, 2C to perform shading correction, it is possible to correct the variation in the brightness in each of
`the respective regions 2A, 2B, 2C to display images at approximately mutually equivalent brightnesses in the
`respective regions 2A, 2B, 2C. Therefore, in the case in which a plurality of images are to be displayed on the CRT
`2 to perform comparative diagnosis, it is possible to perform accurate comparative diagnosis, and, through this, it is
`possible to prevent misdiagnosis resulting fromthe effects of shading.
`[0014]
`
`Note that, in the embodiments discussed above, an example of shading correction in the case in which the
`CRT 2 has been divided vertically in three was described, but it is also possible to apply the present invention with
`any division format, such as three horizontal divisions or four divisions.
`{OO15}
`
`In addition, in the aforementioned embodiments, a CRT 2 was divided, and images were displayed in the
`respective divided regions 2A, 2B, 2C, but even in the case in which the CRT 2 is not divided and one image is
`displayed, variation in brightness resulting from shading is apparent at each of the portions of the CRT 2. In the case
`in which one image is to be displayed on a CRT inthis way, the brightness of each of the portions of the CRT 2 may
`be detected by the detecting means 3 similarly to the embodiments discussed above, the detection result may be
`compared at the comparing means 4, and correction of the image signals of each of the respective portions may be
`performed based on this comparison result by the shading correcting means |. By performing shading correction on
`the image signals so that the brightness of each of the portions of the CRT 2 becomes equivalent in this way, even if
`there is variation in the brightness of each of the portions of the CRT 2, it is possible for this variation to be
`corrected and for an accurate image in which there are no effects of shading to thereby be displayed on the CRT 2.
`(BRIEF DESCRIPTION OF THE DRAWINGS)
`FIG. 1
`
`FIG. 1 is a block diagram that shows an embodiment of an image display apparatus according to the present
`invention.
`FIG. 2
`
`FIG.2 is a graphthat showsthe brightnesses of the respective regions of the CRT.
`(DESCRIPTION OF SYMBOLS)
`1
`shading correcting means
`2
`light emitting display means (CRT)
`2A, 2B, 2C
`region
`3
`detecting means
`4
`comparing means
`5
`gradation correcting means
`SI, $2, 83
`image signal
`
`

`

`Japanese Unexamined Patent Application Publication H9-198019
`(6)
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