`:1 CONDITIONS
Contents
1. input side viewing conditions adaptation luminance LA cd m a white point relative XYZ value X p Y y Zy relative luminance of background Yb and a surrounding lumi nance level are set based on the Exif tag information 92 The input profile 21 is set by the process in FIG 5 based on the input viewing condition The viewing conditions mean parameters based on a human color appearance model Specifically the viewing condition parameters includes parameters such as absolute luminance hereinafter referred to as the adaptation lumi nance LA cd m in the adaptation field 406 a white point relative XYZ value Xj Y py Zy relative luminance in the background field 404 hereinafter referred to as the relative luminance of background Yb a surrounding lumi nance level the type ofa light source and the color space etc viewing condition parameters are necessary to convert the relative XYZ value of a color patch into the JCh value or value on the color appearance space independent from viewing conditions The adaptation luminance LA value is usually set at 20 of the white point absolute luminance in the adaptation field 406 FIG 4 The surrounding luminance level is set at Aver age when the relative luminance value of background is higher than 20 of the white point in the adaptation field 406 at Dim when it is lower than 20 or at Dark when it is almost 0 The c2. 2005 025611 LLP 51 Int CI 57 ABSTRACT H04N 5 228 2006 01 A color processing method which sets viewing conditions 52 U S Cl easily and properly from shooting conditions added to an USPC 22d 348 222 1 348 223 1 348 571 image Shot image data and shooting conditions of the image 348 229 1 382 167 382 162 382 274 382 254 are obtained Input side viewing conditions from the 382 276 358 518 358 519 358 520 358 521 obtained shooting conditions are set The image data with a 58 Field of Classification Search color appearance model based on the set input side viewing USPC 348 222 1 229 1 223 1 571 382 162 382 167 274 254 276 358 518 521 See application file for complete search history v g gt INPUT SIDE VIEWING CONDITION SETTING UNIT INPUT SIDE VIEWING CONDITIONS CONDITIONS conditions are converted 9 Claims 9 Drawing Sheets D50 INPUT SIDE VIEWING 202 A OUTPUT SIDE VIEWING CONDITIONS RELATIVE 4y CONDITIONS 23 OUTPUT SIDE VIEWING US 8 493 465 B2 17 5 PATENT DOCUMENTS 2002 0196346 Al 12 2002 Nishio etal 348 207 2 2003 0016862 1 2003 0034986 1 2003 0184779 1 2004 0141069 1 2004 0228523 1 2004 0228524 1 2005 0168596 1 2005 0169523 1 2007 0058186 1 cited by examiner 11 2004 11 2004 8 2005 8 2005 3 2007 Hibi et al Okutsu et al Ito et al Hayaishi Tanaka
3. U S Patent Jul 23 2013 Sheet 1 of 9 US 8 493 465 B2 FIG 1 101 IMAGE PICKUP UNIT RECORDING UNIT 103 OPERATING UNIT 104 US 8 493 465 B2 Sheet 2 of 9 Jul 23 2013 U S Patent MOQVHS 1 H3H1V3M OF YAHLVAM 3NH HSVH rY NALSONNL dAV11N39 3H0fl c ONLLL3S 40 3S V2 NI 3ounos LHD AO 3dAL ooJnoS1uDr SYNLYAdV SN3T1 ALIALLISN3S OS 114 sBuneupeedsosl LHONMAVG 0 po __ VSV AllHOlHd d33d H31L0HS v AlldOldd SHNLYAdY Nvdu9Oud MAINVM EY Po 0 TOHINOO SHNSOAXS psn 390508 5 eunuemsodx3 _______ 99 ___ 3LIHM NOILVAHOANI 3IX3 de Did E Vols Vc DIA US 8 493 465 B2 Sheet 3 of 9 Jul 23 2013 U S Patent g9u9gopy gt AOVdS eoedgJojo INVNIANTI 08 SZ 990 INVNIARTTII 88 Vs MN I1N39S3HOf113 3 LIHM INBVM AV dV LN39S3u0f113 3LIHM LNS0SSYON 13 dV 1 N39S380fl TS Y40109 DIA U S Patent Jul 23 2013 Sheet 4 of 9 US 8 493 465 B2 FIG 3 VIEWING CONDITION PARAMETER SETTING PROC
4. a program code of software which realizes the func tions of the above described embodiment is stored and caus ing a computer or CPU or MPU of the system or apparatus to read out and execute the program code stored in the storage medium In this case the program code itself read from the storage medium realizes the functions of the above described embodiment and hence the program code and a storage medium on which the program code is stored constitute the present invention Further it is to be understood that the functions of the above described embodiment may be accomplished not only by executing the program code read out by a computer but also by causing an OS operating system or the like which operates on the computer to perform part or all of the actual operations based on instructions of the program code Further it is to be understood that the functions of the above described embodiment may be accomplished by writ ing the program code read out from the storage medium into a memory provided in an expansion board inserted into a computer or a memory provided in an expansion unit con nected to the computer and then causing a CPU or the like provided in the expansion board or the expansion unit to perform a part or all ofthe actual operations based on instruc tions of the program code Further the above program has only to realize the functions ofthe above mentioned embodiment on a computer and the form of the program may
5. conditions from the obtained shooting conditions and a con verting step of converting the image data with a color appear ance model based on the set input side viewing conditions Preferably the input side viewing conditions contain light source white point information and the converting step con verts the image data into device independent color space data US 8 493 465 B2 3 with converting information corresponding to the light source white point data and the device independent color space data is converted with the color appearance model based on the input side viewing conditions Preferably the shooting conditions contain exposure time film ISO sensitivity and lens aperture and the input side viewing conditions contain adaptation luminance relative Iuminance of background and surrounding luminance level To attain the above object in a third aspect of the present invention there is provided an image pickup apparatus com prising an obtaining unit that obtains shot image data and shooting conditions of the image data a setting device that sets input side viewing conditions from the obtained shooting conditions and a converting device that converts the image data with a color appearance model based on the set input side viewing conditions Preferably the input side viewing conditions contain light source white point data and the converting device converts the image data into device independent color space data with conv
6. data under an light source The XYZ data under the light source of output viewing conditions the light source is converted into CMYK data under A light source by using the output profile 26 Refer to Japanese Laid Open Patent Publication Kokai No 2000 050086 U S Pat No 6 542 634 for example Conventionally there has been another problem that it is a user that needs to set input and output viewing condition parameters through a user interface which is too complicated for an average user to understand A method in which viewing condition parameters for each viewing condition are pre stored in a profile in order to facilitate the user setting and a user needs to choose one of the pre stored viewing condition parameters has also been used However it is difficult to properly set the viewing condition parameters for an image shot by a digital camera because the viewing conditions at a shooting place are unclear and the shooting conditions are different SUMMARY OF THE INVENTION It is an object of the present invention to provide a color processing method that sets viewing conditions easily and properly from shooting conditions added to an image a pro gram thereof and an image pickup apparatus To attain the above object in a first aspect of the present invention there is provided a color processing method com prising an obtaining step of obtaining shot image data and shooting conditions of the image
7. from a bunch of profiles in response to a plurality of light sources pre held based on the input side viewing condi tion white point relative XYZ value obtained in the step S313 in FIG 3 Then ifthere is any white point relative XYZ value result ing in the profile is equivalent to the input side viewing condition white point relative XYZ value X Y y Zp YES to a step S501 the profile is selected in a step 5502 followed by terminating the process Meanwhile as a result of the determination in the step S501 if it is not equivalent a profile corresponding to a white point closest in a chromaticity diagram to the input side viewing condition white point relative XYZ value Y y Z y is selected Viewing condition white point chromaticity y and white point chromaticity y2 of a profile white point relative XYZ value X Y Z are calculated with the follow ing relational expressions based on the input side viewing condition white point relative XYZ value Y y Zy ina step S503 x 7XVOG Y EZ YI OG EY 2 X25X MAY AZ y Y X AY AZ Next a profile in response to the shortest distance dist x x y y3X in a chromaticity diagram between the viewing condition white point chromaticity x y and the profile white point chromaticity x gt is selected in a step S504 Thereby even if among profiles dependent on light sources any white point relative XYZ value is not equivalent to
8. nota user has instructed updating ofthe viewing conditions in a step S303 Asaresult ofthe determination in the step S303 ifthe user does not instruct updating the viewing condition parameter pre stored in the information processing unit in response to the color space defined in the Exif tag information are set as an input side viewing conditions in the step S304 For example if sRGB is defined as a color space the viewing condition parameters set in a step S304 are an adap tation luminance value 16 cd m a white point relative XYZ value 0 9505 1 0000 1 0891 a relative luminance value of background 2096 and a surrounding luminance level Dim This initialization setting is performed under a light source D 65 Back to FIG 3 if the color space is determined as unde fined in the step S302 or if the user instructs updating of the viewing conditions in the step S303 then the process pro ceeds to a step S306 In the step S306 the imaging object brightness Bv APEX is obtained based upon the shooting conditions of the Exif tag data 92 stored in the image file 90 and B cd m is obtained from the Bv APEX Specifically Av Tv and Sv values are obtained with the formulas mentioned below each of which are APEX Addi tive Photographic EXposure value of lens aperture F expo sure time T sec and film ISO sensitivity 2 Tv log gt 7 Sv log 454 3 125 Between the exposure index value Ev APEX by
9. the viewing condition white point relative XYZ value a profile dependent on a light source can be selected According to an embodiment of the present invention explained above the following effects can be achieved Moreover input side viewing conditions can be set auto matically by calculating the viewing condition parameters from the shooting conditions stored as additional data of the image Furthermore the viewing condition parameters can be set with great credibility by changing the viewing condition parameter setting value according to the contents of the expo sure control program stored as additional data of the image Profiles dependent on the light source can be selected auto matically by selecting a profile based on the additional data of the image Meanwhile the shooting condition data may be obtained from not only Exif tag data but also other data in response to the image information A user may set the shooting conditions with the user interface It is easier for a user proficient in camera shooting to set the shooting conditions rather than to set the viewing conditions directly US 8 493 465 B2 9 Furthermore in color matching so long as it is performed in response to viewing conditions any other matching method may be all right It goes without saying that the object of the present inven tion may also be accomplished by supplying a system or an apparatus with a storage medium or a recording medium in which
10. the relative luminance of background is calculated with the shooting condition parameter value hereinafter referred to as another shooting condition parameter value of the Exif tag information to a shot image ofthe gray chart The another shooting condition parameter value men tioned above is not limited to the shooting condition param eter value of the Exif tag information of a shot image to the gray chart if the relative luminance value of background be corrected in the case of manual exposure Ina step S310 the luminance B cd m is calculated based on the shooting condition data ofthe gray chart for example lens aperture and shutter speed Ina step S311 the relative luminance value of background YB 96 is corrected to 18 B B 96 Inastep S312 the surrounding luminance level is decided The surrounding luminance level according to the embodi ment of the present invention is set in response to the relative luminance value of background That is the surrounding luminance level is set at Average when the relative lumi nance value of background is higher than 20 at Dim when it is lower than 2096 or at Dark when it is almost 096 However it is set at Average regardless of the relative Iuminance value of background in the case of manual expo sure In a step S313 the white point relative XYZ value Y p Z 15 calculated When the white point chromaticity param eter value x y is set fo
11. view which is useful in explaining a conven tional color matching among different output devices input and output viewing conditions being considered FIGS 8A to 8C are views showing APEX conversion tables and FIG 9 is a view which is useful in explaining the color matching in this embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the drawings showing preferred embodiments thereof It should be noted that the relative arrangement of the components the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise 20 25 30 35 40 45 50 55 60 65 4 FIG 1 is a block diagram schematically showing the con struction of a digital camera as an image pickup apparatus according to an embodiment of the present invention In FIG 1 a digital camera 100 is provided with the follow ing construction elements linked to one another through a bus An image pickup unit 101 images an image object A CPU 102 controls the entire digital camera 100 A recording unit 103 records an image imaged by the image pickup unit 101 as a file format together with the Exiftag information An operating unit 104 inputs user s instructions relating to image shooting FIGS 2A to 2B are views which are useful in explaining the data contained in an Exif
12. ESS 5301 8302 COLOR SPACE UNDEFINED gt ES 304 TS s 5303 VIEWING CONDITIONS UPDATED READ YES VIEWING CONDITION CALCULATE BRIGHTNESS 3306 PARAMETERS OF SHOOTING OBJECT 5307 CALCULATE ADAPTATION ILLUMINANCE LA AND RELATIVE LUMINANCE OF BACKGROUND Yb S308 EXPOSURE CONTROL MODE NYES MANUAL 5309 GRAY CHART SHOOTING IMAGE DATA 5310 CALCULATE B 8311 CORRECT Yb VALUE TO 18 B B S312 3 DECIDE SURROUNDING LUMINANCE LEVEL 5313 CALCULATE WHITE POINT RELATIVE XYZ VALUE 5305 PROFILE MAKING PROCESS 5314 COLOR MATCHING END U S Patent Jul 23 2013 Sheet 5 of 9 US 8 493 465 B2 402 U S Patent CALCULATE CHROMATICITY OF VIEWING CONDITION WHITE POINT AND THAT OF PROFILE WHITE POINT SELECT PROFILE TO SHORTEST DISTANCE IN CHROMATICITY DIAGRAM BETWEEN VIEWING CONDITION WHITE POINT CHROMATICITY AND PROFILE WHITE POINT CHROMATICITY Jul 23 2013 Sheet 6 of 9 US 8 493 465 B2 FIG 5 PROFILE MAKING PROCESS 5501 WHITE POINT OF ANY LIGHT SOURCE DEPENDENT PROFILES COINCIDE WITH THAT OF VIEWING CONDITIONS YES SELECT PROFILE 5502 FIG 6 601 602 603 5 25 XYZso B CMYK U S Patent Jul 23 2013 Sheet 7 of 9 US 8 493 465 B2 FIG 7 lt gt Y D50 INPUT SIDE VIEWING soe A OUTPUT SIDE VIEWING CONDITIONS RELATIVE 23 C INPUT SIDE OUTPUT SIDE VIEWING VIE
13. US008493465B2 a2 United States Patent 10 Patent No US 8 493 465 B2 Ohga 45 Date of Patent Jul 23 2013 54 COLOR PROCESSING METHOD PROGRAM 56 References Cited THEREFOR AND IMAGE PICKUP APPARATUS U S PATENT DOCUMENTS 5 596 428 A 1 1997 Tytgat et al 75 Inventor Manabu Ohga Ohta ku JP 5 838 333 11 1998 Matsuo 6 226 011 5 2001 Sakuyama et al 73 Assignee Canon Kabushiki Kaisha 6 542 634 B1 4 2003 Ohga 6 594 388 Bl 7 2003 Gindele et al Notice Subject to any disclaimer the term of this p 10200 Kiyokawa al patent is extended or adjusted under 35 6 816 179 B2 11 2004 Hanyu U S C 154 b by 0 days 6 999 617 2 2006 Ohga 7 002 623 2 2006 Ohyama et al 21 Appl No 13 196 091 7 006 105 B2 2 2006 Deishi et al 3 7 369 608 B2 5 2008 Okutsu et al 7 397 947 B2 7 2008 et al Q2 Filed 2 2011 7480421 B2 1 2009 Henley 7 515 744 B2 4 2009 Okutsu et al 65 Prior Publication Data 2002 0027603 Al 3 2002 Kuwata et al US 2011 0285870A1 24 2011 Continued Related U S Application Data FOREIGN DOCUMENTS panes 11 017970 1 1999 62 Division of application No 11 344 515 filed on Jan JP 2000 050086 A 2 2000 31 2006 now Pat No 8 013 903 JP 2002 238056 A 8 2002 30 Foreign Application Priority Data Primary Examiner Antoinette Spinks 74 Attorney Agent or Firm Rossi Kimms amp McDowell Feb 1 2005 1
14. WING CONDITIONS CONDITIONS US 8 493 465 B2 Sheet 8 of 9 Jul 23 2013 U S Patent 28 DIA 0002 1 Oi 9 6 8 88 DIA V8 DIA US 8 493 465 B2 Sheet 9 of 9 Jul 23 2013 U S Patent LINN ONILLAS NOLLICINOO ONIMAIA SNOILIGNOO 3415 SNOLLIQNOO ONIM3IA LAdLNO VO osa v1va RA E A mo SZAXL 894 ONILOOHS 9c 56 o 4 12 311108897 06 ez 3ALLV T3H SNOLLIGNOD ONIMAIA FAIS 108100 Y 395 ONIM3IA 3915 LNANI OSG E it 6 OI US 8 493 465 B2 1 COLOR PROCESSING METHOD PROGRAM THEREFOR AND IMAGE PICKUP APPARATUS CROSS REFERENCE TO RELATED APPLICATION This is a divisional of and claims priority from U S patent application Ser No 11 344 515 filed Jan 31 2006 the con tent of which is incorporated herein by reference BACKGROUND OF THE INVENTION 1 Field of the Invention The present invention relates to a color processing method that sets viewing conditions based on shooting conditions a program thereof and an image pickup apparatus 2 Description of the Related Art Conventionally color matching among different devices is generally made in such a method as is shown in FIG 6 Specifically input data such as RGB data is converted into XYZ data in a de
15. background field 403 and the surrounding field 404 is called an adaptation field 405 Typical color appearance models such as CIECAM97s and CIE define the viewing condition parameters neces sary to convert a relative XYZ value ofa color patch into a JCh value or QMh value on the color appearance space indepen dent from viewing conditions Next input and output viewing conditions being consid ered a color matching method performed among different output devices will be described with reference to FIG 7 FIG 7 is a view which is useful in explaining the color matching among different output devices considering input output viewing conditions A light source on the input side is D50 and a light source on the output side is First the input data such as the RGB data under a D50 light source is converted into XYZ data under the D50 light source by using an input profile 21 Next the converted XYZ data is subjected to the forward conversion of a color appearance model according to the input side viewing conditions in a CAM 22 and then is 5 30 40 45 65 2 converted into JCh data 23 or QMh data 24 in color space independent from the viewing conditions Then the gamut mapping is performed to the JCh data 23 or QMh data 24 The JCh data 23 or QMh data 24 is subjected to inverse conversion of the color appearance model according to the output side viewing conditions in CAM 25 and then is converted into XYZ
16. be an object code a program executed by an interpreter or script data supplied to an OS Examples of the storage medium for supplying the pro gram code include a floppy registered trademark disk a hard disk a magnetic optical disk a CD ROM a CD R a CD RW a DVD ROM a DVD RAM a DVD RW a DVD RW a magnetic tape a nonvolatile memory card and a ROM Alternatively the program is supplied by downloading from another computer a database or the like not shown con nected to the Internet a commercial network a local area network or the like This application claims the benefit of Japanese Application No 2005 025611 filed Feb 1 2005 which is hereby incor porated by reference herein in its entirety What is claimed is 1 An image processing apparatus comprising a recording unit configured to record an image data of a shot image together with additional information regard ing a shooting condition of the shot image data a determining unit configured to determine whether a color space of the image data is defined or undefined as a shooting condition parameter value based on the addi tional information of the image data a first viewing condition setting unit configured to set in a case where said determining unit determines that the color space of the image data is defined a first viewing condition as an input viewing condition for the image data based upon the defined color space asecond viewing condition setting un
17. data a setting step of setting input side viewing conditions from the obtained shooting conditions and a converting step of converting the image data with a color appearance model based on the set input side viewing conditions Preferably the input side viewing conditions contain light source white point information and the converting step con verts the image data into device independent color space data with converting information corresponding to the light source white point data and the device independent color space data is converted with the color appearance model based on the input side viewing conditions Preferably the shooting conditions contain exposure time film ISO sensitivity and lens aperture and the input side viewing conditions contain adaptation luminance relative luminance of background and surrounding luminance level Preferably the shooting conditions contain the type of exposure control method the relative luminance of back ground is set at 18 when the exposure control method is manual and the relative luminance of background is set at any value different from 18 when the exposure control method is automatic To attain the above object in a second aspect of the present invention there is provided a computer readable program for executing a color processing method comprising an obtaining step of obtaining shot image data and shooting conditions of the image data a setting step of setting input side viewing
18. e of automatic exposure AE because the pho tometry of an imaging object is performed the EV value obtained from the lens aperture Av and the shutter speed US 8 493 465 B2 7 Tv is not always equivalent to the Ev value by an exposure meter This is because the reflectance of the imaging object is not always 1896 and when the shooting object is whitish high reflectance an automatically set exposure is inclined to be rather low In a step S308 if it is determined that the exposure control modeis manual exposure the process proceeds to a step S312 because it is not required to correct the relative luminance of background set in the step S307 Meanwhile in the step S308 if it is determined that the exposure control mode is automatic exposure in a step S309 it is determined whether or not there is a shot image of a gray chart 1896 gray shot under the same viewing conditions as those of a shot image to be processed in a step S309 If there is not a shot image of the gray chart the relative luminance value of background is corrected to 2096 and the process proceeds to a step S312 As was mentioned above it often happens that an actual imaging object is whiter and higher in reflectance than gray 1896 Therefore according to the embodiment of the present invention 2096 is applied as an experience value On the other hand if there is a shot image of a gray chart the process proceeds to a step S310 and the corrected value of
19. erting data in response to the light source white point data and converts the device independent color space data with the color appearance model based on the input side viewing conditions Preferably the shooting conditions contain exposure time film ISO sensitivity and lens aperture and the input side viewing conditions contain adaptation luminance relative Iuminance of background and surrounding luminance level The above and other objects features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a block diagram schematically showing the con struction of a digital camera as an image pickup apparatus according to an embodiment of the present invention FIGS 2A to 2B are views which are useful in explaining the data contained in an Exiftag of an image file made by the digital camera of FIG 1 FIG 3 is a flowchart showing the procedure of an input side viewing condition parameter setting process that is per formed by an input side viewing condition setting unit in FIG 9 FIG 41s a view which is useful in explaining a human color appearance model FIG 5 is a flowchart showing the procedure of a profile making process that is performed in a step 305 in FIG 3 FIG 6 is a view which is useful in explaining conventional color matching among different devices FIG 7 is a
20. etermining step of determining whether a color space of the image data 15 defined or undefined as a shooting condition parameter value based on the additional infor mation of the image data a first viewing condition setting step of setting in a case where said determining step determines that the color space of the image data is defined a first viewing con dition as an input viewing condition for the image data based upon the defined color space a second viewing condition setting step of setting in a case where said determining step determines that the color space of the image data is undefined a second viewing US 8 493 465 B2 11 condition as the input viewing condition for the image data based upon other shooting condition parameter val ues contained in the additional information of the image data a profile setting step of setting an input profile correspond ing to the input viewing condition set in either one of said first viewing condition setting step or said second viewing condition setting step and a converting step of converting the image data into an image data independent from the input viewing condi tion with the input profile set in said profile setting step and the viewing condition set in either one of said first viewing condition setting step or said second viewing condition setting step 6 non transitory machine readable medium encoded with a computer readable program executable by a computer for executi
21. it configured to set in a case where said determining unit determines that the color space of the image data is undefined a second viewing condition as the input viewing condition for the 20 25 35 40 45 50 55 60 65 10 image data based upon other shooting condition param eter values contained in the additional information ofthe image data a profile setting unit configured to set an input profile corresponding to the input viewing condition set by either one of said first viewing condition setting unit or said second viewing condition setting unit and a converting unit configured to convert the image data into an image data independent from the input viewing con dition with the input profile set by said profile setting unit and the input viewing condition set by either one of said first viewing condition setting unit or said second viewing condition setting unit 2 Animage processing unit as claimed in claim 1 wherein the input viewing condition contains adaptation lumi nance relative luminance of background a surrounding Iuminance level and a white point said profile setting unit sets the profile based on the white point and said converting unit converts the image data with the pro file and converts the converted image data with a color appearance model corresponding to the viewing condi tion 3 An image processing unit as claimed in claim 2 wherein the shooting condition contains exposure
22. ng a color processing method comprising a recording step of recording an image data of a shot image together with additional information regarding a shoot ing condition of the shot image a determining step of determining whether a color space of the image data is defined or undefined as a shooting condition parameter value based on the additional infor mation of the image data a first viewing condition setting step of setting in a case where said determining step determines that the color space of the image data is defined a first viewing con dition as an input viewing condition for the image data based upon the defined color space asecond viewing condition setting step of setting case where said determining step determines that the color 20 25 30 12 space of the image data is undefined a second viewing condition as the input viewing condition for the image data based upon other shooting condition parameter val ues contained in the additional information of the image data a profile setting step of setting an input profile correspond ing to the input viewing condition set in either one of said first viewing condition setting step or said second viewing condition setting step and a converting step of converting the image data into an image data independent from the input viewing condi tion with the input profile set in said profile setting step and the viewing condition set in either one of said first viewi
23. ng condition setting step or said second viewing condition setting step 7 Animage processing unit as claimed in claim 1 wherein said second viewing condition setting unit sets in a case where said determining unit determines that the color space ofthe image data is undefined the second viewing condition without a user input 8 A color processing method as claimed in claim 5 wherein said second viewing condition setting step sets in a case where said determining step determines that the color space of the image data is undefined the second viewing condition without a user input 9 A non transitory machine readable medium as claimed in claim 6 wherein said second viewing condition setting step sets ina case where said determining step determines that the color space ofthe image data is undefined the second viewing condition without a user input
24. olor matching process shown in FIG 9 is performed by information processing device such as personal comput US 8 493 465 B2 5 ers for example This information processing device pre stores profiles of a digital camera corresponding to different light sources The profiles of a digital camera corresponding to light sources are obtained from the white point relative XYZ value under different light sources and RGB values of the digital camera 100 The white point relative XYZ value under different light sources is obtained by applying spectral data of a plurality of standard light sources including fluo rescent lamps to spectral reflectance obtained from perform ing color reading of each patch of color targets such as Gretag Macbeth Color Checker DC It should be noted that for example the output side source viewing conditions are set based on a user s manual instruction in a conventional manner or the preset standard viewing conditions are set FIG 3 is aflowchart showing the procedure of an input side viewing condition parameter setting process that is per formed by the input side viewing condition setter 93 in FIG 9 In a step S301 first the Exif tag data is read in In a step S302 it is determined whether or not the color space is unde fined by referring to the color space information of the Exif tag information As a result of the determination in the step 5302 if the color space is defined it is determined whether or
25. r Exif tag information the relative XYZ value X Zy is calculated with the following relational expressions 100 0 100 0 Zy 1 x y y 100 0 Meanwhile when the type of light source is set for Exiftag information a representative white point in response to the set light source is read out from a list of representative white points of respective light sources held in an information pro cessor in advance and the relative XYZ value X p Y y Zy is calculated with the following relational expressions 92100 0 100 0 1 100 0 _ 0 20 35 40 45 50 55 65 8 By the above process the viewing condition parameters can be set from the Exif tag information of a shooting image file Therefore the viewing conditions proper for an image shot by a digital camera can be set easily without any aid from a user Next a profile making process of FIG 5 which will be described below is carried out in a step 5305 to thereby select a profile dependent on a light source before performing color matching step S314 followed by terminating the process FIG 5 is a flowchart showing the procedure of a profile making process that is performed in a step S305 in FIG 3 In this procedure the input side profile 21 is set based on the input side viewing conditions set by the input side viewing condition setter 93 Furthermore preliminarily one profile is selected
26. ss B cd m is calculated as follows Bv log B NK NK 3 426 B 3 426 2Bv 65 11 cd m In a step S307 the adaptation luminance and the relative luminance of background are calculated The adaptation luminance LA cd m is equivalent to the luminance B cal culated in the step S306 The relative luminance of back ground Yb 96 is set at 18 in a step S307 In the case of proper exposure the luminance B is assumed to represent the luminance of reflected light obtained when the shooting object is 18 gray In a step S308 it is determined from the exposure control mode data of the Exif tag data whether or not the exposure control mode is manual exposure In the case of manual exposure because it can be consid ered that a photographer has set the optimum exposure con ditions lens aperture Av shutter speed Tv with an Ev value an exposure meter indicates it can be assumed that By indi cates the brightness to an imaging object of reflectance 18 On the contrary in the case of automatic exposure AE because the exposure conditions are automatically set with a photometric sensor in a digital camera it can be assumed that By indicates the brightness to an actual imaging object It often happens that an actual imaging object is whiter and higher in reflectance than gray 18 Therefore in the case of automatic exposure the relative luminance of background Yb 5 set in the step S307 is required to be corrected In the cas
27. tag of an image file made by the digital camera of FIG 1 Shooting condition parameter values such as white point chromaticity White Point x y exposure time T sec the type of exposure control program ISO sensitivity ASA lens aperture F the type of light sources in the case of manual setting and color space etc are described in the Exif tag of this embodiment In addition according to this embodiment n both the white point chromaticity and the type of light sources are supposed to be described as shooting condition parameter values in the Exif tag but only one of them may be described as the shooting condition parameter values in the Exif tag According to this embodiment the following color match ing is performed to image data with Exif tag data obtained from the digital camera 100 FIG 9 is a view which is useful in explaining the color matching in this embodiment The color matching is different from the conventional color matching FIG 7 in that the input side source viewing condition is based on the Exiftag information of an image file In FIG 9 component elements corresponding to those of FIG 7 are designated by identical reference numerals and description thereof is omitted Inthe color matching shown in FIG 9 first an image data with Exif tag information is obtained Next an input side viewing condition setting unit 93 performs the processes shown in FIG 3 which will be hereinafter described and an
28. the exposure meter equivalent to the brightness to 18 gray and the four values of film ISO sensitivity Sv APEX the shut ter speed Tv APEX the lens aperture Av APEX and the imaging object brightness Bv APEX the following rela tional expressions are true under the optimum exposure con dition Ev 10 as is shown in an APEX conversion table in FIGS 8A to 8C Ev AveTv BveSv 20 25 30 35 40 45 50 55 60 65 6 For example if the exposure time is 425 sec and the lens aperture is F2 8 then Tv 7 APEX and Av 3 APEX are obtained and 7 3 10 is true If 10 is true even the combination of Tv 6 APEX Vo sec and Av 4 APEX F4 makes it possible to shoot with proper exposure Based on the aforementioned relational expressions the brightness Bv APEX of a shooting object can be obtained as follows Av Tv Sv 2log F log T log ASA 3 125 Furthermore the following relational expressions are true between the brightness ofan imaging object Bv APEX and the brightness B cd m By log gt B NK B NK 2Bv For example if lens aperture F is 2 8 the exposure time T sec is and the film ISO sensitivity ASA is 200 then Bv APEX is calculated as follows Av Tv Sv 2log F log T log ASA 3 125 2log Q 8 log 1 160 log 200 3 125 2432 Based upon this calculated Bv APEX the brightne
29. time film ISO sensitivity and lens aperture and the image processing unit further comprises a calculating unit configured to calculate the adaptation luminance from the exposure time the film ISO sensitivity and the lens aperture 4 An image processing apparatus as claimed in claim 1 further comprising an exposure determining unit configured to determine based on the additional information of the image data whether an exposure control mode at the time of obtain ing the image data is manual exposure or automatic exposure and wherein said second viewing condition setting unit calcu lates relative luminance of background from exposure time film ISO sensitivity and lens aperture contained in the additional information of the image data to set the calculated relative luminance of background as a param eter contained in the viewing condition in a case where said exposure determining unit determines that the exposure control mode is the automatic exposure while correcting the calculated relative luminance of back ground to set the corrected relative luminance of back ground as a parameter contained in the viewing condi tion in a case where said exposure determining unit determines that the exposure control mode is the manual exposure 5 color processing method comprising a recording step of recording an image data ofa shot image together with additional information regarding a shoot ing condition of the shot image a d
30. vice independent color space by using an input profile 601 Next a color outside a color gamut of an output device cannot be expressed by the output device Therefore color gamut mapping in a PCS 602 converted XYZ data into mapped XYZ data within the color gamut of the output device Then the mapped data is converted from the XYZ data in device independent color space to CMYK data in device dependent color space by using the output profile 603 However it is difficult to perform color matching under different viewing conditions A human color appearance model must be introduced so that color matching is realized under different viewing conditions The human color appearance model is designed so that human color appearance may be estimated accurately when a color patch of a viewing angle 2 is given and defines a human field of view as is shown in FIG 4 Generally a standard colorimetric observer 401 in CIE 1931 color system has an applicable range at a viewing angle 1 10 49 therefore this applicable range field is divided into a stimulus field 402 below a viewing angle 2 and an adjacent field 403 below a viewing angle 4 Then the field between the adjacent field 403 at a viewing angle 4 and a field at a viewing angle 10 is called a background field 404 and a field surrounding the background field 404 is called a surrounding field 405 Fur thermore a field of vision consisting of the stimulus field 402 the adjacent field 402 the
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