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The ColorChecker DC chart has a large white patch in the center, immediately surrounded by a set of various neutral gray patches. These are used for global color balance and tone reproduction purposes. The center patch is very helpful to the photographer in determining the proper exposure of the chart (a topic that will be discussed in the next chapter).
The patches around the outer edge of the chart allow you to judge the uniformity of illumination of the chart (a topic that is discussed further here). If you see that the lighting is not even across the chart, you are advised to correct this problem before proceeding to make the profile.
Colors S4 through S11 have a glossy surface finish, and because of that, they can represent more extreme colors which extend the "knowable" color range of the profile. However, many photographers feel that this gloss can pick up unwanted reflections, thereby polluting the color of the patch, resulting in an inferior profile. Other photographers are comfortable setting up the shot in such a way as to avoid these reflections. Since there is no consensus on this matter, inCamera may instructed to either include or exclude the glossy colors when the profile is made.
ColorChecker DC charts are available in two forms: batch measured and custom measured. In either case, a reference file for the chart is provided with the chart. Use this file with inCamera. Your reference file may or may not contain spectral data. Older reference files did not, but GretagMacbeth (the manufacturer of the ColorChecker DC chart) has recently made spectral reference files available. inCamera will work with either kind of reference file, but you can specify your light source only when using spectral reference files. The inCamera installation package includes a spectral reference file from GretagMacbeth named ColorChecker DC.txt.
Power Users Only: Custom Data Reference Files
If you wish to make a custom reference file, it must be in one of the two following formats.
The beginning and ending of ColorChecker DC.txt (an example of the spectral format) is shown here:
LGOROWLENGTH 12
CREATED "12/15/2003" # Time: 15:08
INSTRUMENTATION "SpectroScanT"
MEASUREMENT_SOURCE "Illumination=D50 ObserverAngle=2° WhiteBase=Abs Filter=No"
ILLUMINATION_NAME "D50"
OBSERVER_ANGLE "2"
KEYWORD "SampleID"
KEYWORD "SAMPLE_NAME"
NUMBER_OF_FIELDS 38
BEGIN_DATA_FORMAT
SampleID SAMPLE_NAME nm380 nm390 nm400 nm410 nm420 nm430 nm440 nm450 nm460 nm470 nm480 nm490 nm500 nm510 nm520 nm530 nm540 nm550 nm560 nm570 nm580 nm590 nm600 nm610 nm620 nm630 nm640 nm650 nm660 nm670 nm680 nm690 nm700 nm710 nm720 nm730
END_DATA_FORMAT
NUMBER_OF_SETS 240
BEGIN_DATA
1 A1 0.1406 0.1994 0.3760 0.6298 0.7718 0.8014 0.8049 0.8056 0.8058 0.8039 0.8021 0.8011 0.7984 0.7961 0.7957 0.7937 0.7925 0.7899 0.7856 0.7857 0.7821 0.7787 0.7741 0.7693 0.7663 0.7628 0.7625 0.7644 0.7663 0.7653 0.7644 0.7647 0.7645 0.7659 0.7697 0.7755
2 A2 0.0312 0.0347 0.0339 0.0344 0.0343 0.0342 0.0344 0.0340 0.0335 0.0334 0.0330 0.0329 0.0325 0.0322 0.0321 0.0317 0.0317 0.0314 0.0310 0.0309 0.0304 0.0302 0.0298 0.0297 0.0296 0.0295 0.0297 0.0297 0.0301 0.0301 0.0304 0.0304 0.0303 0.0309 0.0311 0.0316
3 A3 0.0903 0.1232 0.1674 0.1900 0.1937 0.1984 0.2021 0.2036 0.2036 0.2016 0.2005 0.2000 0.1994 0.1998 0.2005 0.2006 0.2008 0.1998 0.1987 0.1987 0.1978 0.1967 0.1943 0.1919 0.1895 0.1870 0.1857 0.1842 0.1833 0.1814 0.1793 0.1771 0.1753 0.1753 0.1758 0.1773
4 A4 0.1383 0.2016 0.3787 0.6342 0.7773 0.8066 0.8101 0.8111 0.8105 0.8088 0.8067 0.8056 0.8028 0.8005 0.8001 0.7982 0.7969 0.7945 0.7903 0.7906 0.7870 0.7835 0.7786 0.7734 0.7704 0.7666 0.7667 0.7681 0.7697 0.7687 0.7679 0.7677 0.7676 0.7684 0.7721 0.7779
5 A5 0.0313 0.0342 0.0340 0.0342 0.0342 0.0341 0.0342 0.0339 0.0335 0.0336 0.0331 0.0329 0.0326 0.0323 0.0321 0.0319 0.0318 0.0314 0.0311 0.0309 0.0303 0.0300 0.0297 0.0295 0.0296 0.0296 0.0298 0.0300 0.0302 0.0304 0.0306 0.0306 0.0308 0.0310 0.0311 0.0317
6 A6 0.0898 0.1256 0.1694 0.1908 0.1958 0.1996 0.2034 0.2050 0.2047 0.2031 0.2017 0.2012 0.2008 0.2009 0.2015 0.2016 0.2016 0.2008 0.1995 0.1997 0.1987 0.1973 0.1951 0.1924 0.1900 0.1874 0.1860 0.1848 0.1835 0.1817 0.1798 0.1774 0.1759 0.1755 0.1765 0.1774
7 A7 0.1428 0.2073 0.3863 0.6390 0.7783 0.8072 0.8105 0.8121 0.8114 0.8100 0.8081 0.8071 0.8041 0.8021 0.8015 0.7999 0.7987 0.7962 0.7918 0.7919 0.7887 0.7851 0.7803 0.7752 0.7720 0.7683 0.7680 0.7695 0.7714 0.7700 0.7692 0.7690 0.7691 0.7698 0.7731 0.7793
8 A8 0.0312 0.0338 0.0342 0.0347 0.0346 0.0347 0.0344 0.0343 0.0341 0.0337 0.0335 0.0333 0.0329 0.0327 0.0325 0.0322 0.0320 0.0317 0.0314 0.0312 0.0308 0.0305 0.0301 0.0300 0.0301 0.0301 0.0302 0.0303 0.0306 0.0309 0.0310 0.0309 0.0309 0.0314 0.0316 0.0311
9 A9 0.0879 0.1256 0.1684 0.1901 0.1957 0.1994 0.2030 0.2055 0.2047 0.2032 0.2020 0.2014 0.2012 0.2013 0.2021 0.2024 0.2022 0.2017 0.2004 0.2004 0.1996 0.1980 0.1962 0.1935 0.1912 0.1890 0.1873 0.1864 0.1851 0.1832 0.1812 0.1790 0.1775 0.1771 0.1777 0.1791
10 A10 0.1354 0.1959 0.3716 0.6268 0.7736 0.8048 0.8090 0.8100 0.8096 0.8078 0.8062 0.8049 0.8022 0.7999 0.7993 0.7976 0.7966 0.7939 0.7897 0.7895 0.7863 0.7827 0.7780 0.7731 0.7698 0.7664 0.7665 0.7680 0.7698 0.7689 0.7674 0.7678 0.7679 0.7689 0.7734 0.7799
11 A11 0.0353 0.0320 0.0347 0.0343 0.0341 0.0344 0.0342 0.0339 0.0335 0.0335 0.0331 0.0331 0.0325 0.0323 0.0323 0.0320 0.0318 0.0315 0.0310 0.0310 0.0305 0.0302 0.0299 0.0297 0.0298 0.0297 0.0298 0.0301 0.0303 0.0306 0.0305 0.0306 0.0307 0.0310 0.0315 0.0312
12 A12 0.0901 0.1242 0.1667 0.1886 0.1940 0.1974 0.2014 0.2031 0.2025 0.2013 0.2000 0.1994 0.1991 0.1991 0.1999 0.2000 0.2000 0.1993 0.1981 0.1980 0.1972 0.1955 0.1935 0.1911 0.1887 0.1863 0.1847 0.1837 0.1825 0.1806 0.1785 0.1762 0.1749 0.1748 0.1751 0.1763
13 B1 0.0898 0.1243 0.1665 0.1889 0.1937 0.1978 0.2015 0.2037 0.2030 0.2016 0.2005 0.1999 0.1997 0.1999 0.2006 0.2009 0.2009 0.2002 0.1989 0.1992 0.1980 0.1966 0.1945 0.1919 0.1896 0.1872 0.1858 0.1845 0.1835 0.1817 0.1795 0.1774 0.1758 0.1758 0.1764 0.1771
14 B2 0.0479 0.0472 0.0461 0.0449 0.0443 0.0440 0.0434 0.0431 0.0422 0.0414 0.0407 0.0401 0.0396 0.0394 0.0394 0.0396 0.0401 0.0411 0.0428 0.0467 0.0538 0.0659 0.0922 0.1423 0.1925 0.2244 0.2425 0.2535 0.2605 0.2650 0.2690 0.2740 0.2804 0.2872 0.2936 0.2998
...
227 S11 0.0462 0.0722 0.1166 0.1527 0.1681 0.1895 0.2217 0.2611 0.3035 0.3575 0.3910 0.3916 0.3599 0.3069 0.2448 0.1849 0.1361 0.0977 0.0691 0.0516 0.0418 0.0359 0.0317 0.0286 0.0269 0.0258 0.0255 0.0256 0.0264 0.0268 0.0260 0.0250 0.0239 0.0237 0.0256 0.0291
228 S12 0.0887 0.1230 0.1669 0.1891 0.1944 0.1987 0.2021 0.2040 0.2033 0.2021 0.2009 0.2000 0.1999 0.2000 0.2008 0.2009 0.2009 0.2001 0.1987 0.1989 0.1978 0.1965 0.1943 0.1918 0.1894 0.1870 0.1855 0.1844 0.1831 0.1815 0.1792 0.1770 0.1757 0.1752 0.1759 0.1769
229 T1 0.0915 0.1247 0.1685 0.1901 0.1951 0.1993 0.2031 0.2051 0.2046 0.2029 0.2017 0.2010 0.2008 0.2010 0.2017 0.2018 0.2017 0.2010 0.1997 0.1997 0.1987 0.1972 0.1950 0.1927 0.1903 0.1879 0.1865 0.1856 0.1845 0.1827 0.1806 0.1786 0.1771 0.1770 0.1774 0.1790
230 T2 0.0341 0.0342 0.0349 0.0354 0.0353 0.0353 0.0351 0.0350 0.0346 0.0344 0.0342 0.0338 0.0337 0.0333 0.0332 0.0330 0.0328 0.0326 0.0321 0.0319 0.0315 0.0312 0.0309 0.0307 0.0308 0.0307 0.0307 0.0310 0.0313 0.0315 0.0314 0.0316 0.0318 0.0318 0.0323 0.0324
231 T3 0.1387 0.1983 0.3765 0.6319 0.7749 0.8055 0.8086 0.8093 0.8091 0.8073 0.8054 0.8045 0.8018 0.7996 0.7993 0.7975 0.7963 0.7940 0.7896 0.7900 0.7868 0.7834 0.7787 0.7740 0.7710 0.7674 0.7675 0.7690 0.7708 0.7698 0.7685 0.7686 0.7684 0.7699 0.7728 0.7798
232 T4 0.0874 0.1217 0.1663 0.1883 0.1932 0.1974 0.2009 0.2031 0.2026 0.2011 0.1998 0.1992 0.1991 0.1991 0.2000 0.2000 0.2002 0.1995 0.1983 0.1984 0.1975 0.1961 0.1939 0.1914 0.1890 0.1867 0.1852 0.1842 0.1829 0.1812 0.1789 0.1768 0.1752 0.1750 0.1756 0.1768
233 T5 0.0316 0.0324 0.0337 0.0339 0.0333 0.0339 0.0336 0.0334 0.0333 0.0331 0.0330 0.0325 0.0323 0.0320 0.0319 0.0316 0.0314 0.0312 0.0307 0.0306 0.0302 0.0298 0.0295 0.0294 0.0295 0.0294 0.0294 0.0297 0.0300 0.0302 0.0303 0.0303 0.0306 0.0306 0.0305 0.0307
234 T6 0.1401 0.1988 0.3761 0.6303 0.7736 0.8040 0.8074 0.8085 0.8079 0.8065 0.8046 0.8039 0.8011 0.7986 0.7981 0.7964 0.7953 0.7929 0.7884 0.7889 0.7855 0.7819 0.7771 0.7723 0.7692 0.7655 0.7653 0.7669 0.7686 0.7675 0.7665 0.7666 0.7665 0.7676 0.7709 0.7781
235 T7 0.0888 0.1224 0.1669 0.1883 0.1936 0.1978 0.2014 0.2035 0.2029 0.2016 0.2002 0.1997 0.1994 0.1997 0.2004 0.2007 0.2007 0.2000 0.1986 0.1989 0.1979 0.1966 0.1946 0.1921 0.1898 0.1873 0.1859 0.1849 0.1835 0.1818 0.1796 0.1774 0.1758 0.1756 0.1765 0.1773
236 T8 0.0310 0.0334 0.0334 0.0333 0.0331 0.0332 0.0331 0.0328 0.0326 0.0326 0.0324 0.0319 0.0318 0.0315 0.0313 0.0311 0.0309 0.0306 0.0303 0.0302 0.0297 0.0294 0.0291 0.0290 0.0290 0.0289 0.0289 0.0293 0.0295 0.0298 0.0296 0.0299 0.0300 0.0299 0.0305 0.0302
237 T9 0.1352 0.1973 0.3741 0.6292 0.7720 0.8021 0.8057 0.8065 0.8068 0.8054 0.8034 0.8030 0.8004 0.7983 0.7980 0.7963 0.7952 0.7927 0.7883 0.7888 0.7854 0.7818 0.7775 0.7728 0.7698 0.7663 0.7663 0.7680 0.7699 0.7687 0.7677 0.7678 0.7678 0.7688 0.7719 0.7785
238 T10 0.0890 0.1239 0.1684 0.1894 0.1949 0.1991 0.2026 0.2046 0.2038 0.2027 0.2014 0.2009 0.2006 0.2008 0.2015 0.2017 0.2017 0.2010 0.1998 0.1999 0.1988 0.1975 0.1954 0.1931 0.1907 0.1882 0.1868 0.1857 0.1844 0.1827 0.1803 0.1783 0.1766 0.1762 0.1776 0.1782
239 T11 0.0312 0.0325 0.0339 0.0338 0.0341 0.0342 0.0342 0.0341 0.0338 0.0336 0.0333 0.0328 0.0327 0.0323 0.0322 0.0320 0.0319 0.0316 0.0312 0.0310 0.0306 0.0302 0.0299 0.0297 0.0296 0.0297 0.0298 0.0300 0.0305 0.0307 0.0307 0.0308 0.0308 0.0308 0.0308 0.0313
240 T12 0.1389 0.1988 0.3755 0.6293 0.7715 0.8018 0.8054 0.8059 0.8059 0.8042 0.8025 0.8017 0.7988 0.7967 0.7964 0.7947 0.7936 0.7913 0.7871 0.7872 0.7839 0.7803 0.7757 0.7707 0.7677 0.7640 0.7640 0.7657 0.7675 0.7665 0.7652 0.7653 0.7657 0.7670 0.7705 0.7773
END_DATA
The patch measurements follow the BEGIN_DATA line, one per line. Each line begins with the data line number, followed by an identifier indicating the column (A through T) and the row (1 through 12), which is followed by the spectral measurement data for the patch. Each measurement consists of 36 numbers, which represent the spectral responses from 380 through 730 nm at 10 nm intervals.
The beginning and ending of a reference file in the non-spectral format is shown here:
Date: 3/27/2000 Time: 19:04
LGOROWLENGTH 12
BEGIN_DATA_FORMAT
Sample_Name XYZ_X XYZ_Y XYZ_Z Lab_L Lab_a Lab_b
END_DATA_FORMAT
BEGIN_DATA
A1 74.79 77.56 64.46 90.58 0.01 -0.46
A2 3.08 3.19 2.77 20.8 0.05 -1.05
A3 18.98 19.71 16.53 51.51 -0.15 -0.64
A4 74.57 77.34 64.38 90.48 -0.01 -0.55
A5 3.1 3.21 2.78 20.87 0.03 -1.07
A6 18.88 19.62 16.44 51.4 -0.15 -0.62
A7 74.65 77.43 64.37 90.52 -0.03 -0.47
A8 3.05 3.16 2.74 20.69 0.03 -1.06
A9 18.86 19.59 16.42 51.37 -0.15 -0.63
A10 74.33 77.13 64.18 90.38 -0.07 -0.53
A11 3.05 3.16 2.74 20.68 0.06 -1.07
A12 18.94 19.67 16.48 51.46 -0.14 -0.6
B1 18.98 19.71 16.53 51.51 -0.15 -0.63
B2 9.28 6.32 3.27 30.2 29.98 11.49
...
S10 17.03 7.57 3.05 33.07 69 17.97
S11 6.56 11.29 24.29 40.07 -37.61 -36.38
S12 18.91 19.64 16.46 51.43 -0.15 -0.61
T1 18.91 19.64 16.46 51.43 -0.15 -0.62
T2 3.05 3.16 2.73 20.67 0.06 -1.02
T3 74.38 77.15 64.2 90.39 -0.01 -0.54
T4 18.94 19.68 16.48 51.47 -0.15 -0.6
T5 3.12 3.24 2.79 20.97 0.02 -0.96
T6 74.2 76.97 63.98 90.31 -0.03 -0.46
T7 18.87 19.61 16.43 51.39 -0.16 -0.62
T8 3.04 3.16 2.73 20.66 0.02 -1.04
T9 74.41 77.19 64.05 90.41 -0.03 -0.36
T10 18.9 19.63 16.46 51.42 -0.15 -0.62
T11 3.09 3.2 2.78 20.82 0.05 -1.1
T12 74.57 77.32 64.19 90.47 0.03 -0.39
END_DATA
The patch measurements follow the BEGIN_DATA line and are presented as seven items per line. The first is the identifier indicating the column (A through F) and the row (1 through 4). The next three items are numbers representing the XYZ values for the patch (relative to the CIE 2° standard observer and the CIE D50 reference illuminant). The last three items are the numbers representing the CIE Lab values for the color.
Your measuring instrument may have come with software that can create a file in one of these formats. If not, the easiest way to make a custom reference file that can be used with inCamera, is to copy the file that is included with inCamera, and then edit it with any text editor that can save plain (unformatted) text files.
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