Color Test Charts

ColorChecker Classic Chart

Brand: ColorSpace
Model: TC021
Product description: The ColorChecker Classic target is designed to deliver true-to-life image reproduction so photographers can predict and control how color will look under any illumination. Each of the 24 colors repres
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Details：

The ColorChecker® 24 Patch Classic target is an array of 24 scientifically prepared natural, chromatic, primary and gray scale colored squares in a wide range of colors. Many of the squares represent natural objects, such as human skin, foliage and blue sky. Since they exemplify the color of their counterparts and reflect light the same way in all parts of the visible spectrum, the squares will match the colors of representative sample natural objects under any illumination, and with any color reproduction process.
Features：
· Array of 24 natural object, chromatic, primary and gray scale colors, arranged in four rows.
· Each square reflects light the same way as its real life counterpart in all parts of the visible spectrum, under any illumination, and with any color reproduction process
· Compare digital reproductions to real life scenes or test targets to measure and analyze differences in color reproduction in any color rendition system.
ColorChekcer Reference Data

1. X-Rite default old: Color space Wt Pt (the default setting prior to 4.4) *This section has been rewritten to reduce confusion.*	Lab* values provided by GretagMacbeth in 2005. The values are in an Excel file, Lab data Iluminate D65 & D50 spectro.xls (click on the link to open or download), that contains 2 degree D65 data used for D65 color spaces and 2 degree D50 data used for D50 color spaces. This is somewhat different from the current practice of always assuming Lab* data was obtained with a D50 illuminant and converting it to D65 (for D65 white point color spaces– sRGB, Adobe RGB, etc.) using a Bradford Transform. The 2 degree D50 data is still in the X-Rite Colorchecker data page (as of March 2016), even though X-Rite has announced changes to the reference values for Colorcheckers manufactured after November 2014). Starting with Imatest 4.4 (March 2016), the reference selection includes another option, X-Rite default: pre-Nov 2014 D50 (described below), that uses the D50 data and converts it to D65 for color spaces with a D65 white point (sRGB, etc.).
2. Babelcolor	Lab* values measured by Danny Pascale of Babelcolor, from Table 2 (bottom) of RGB coordinates of the MacBeth ColorChecker, which is *recommended reading for all Colorchecker users*. Pascale’s D50 values are transformed to D65 using the Bradford transformation for color spaces with a D65 white point.
3. Danes-Picta BST4D	A knockoff of the Colorchecker (same geometry with different colors) from Danes-Picta in the Czech Republic (on their Digital Imaging page).
4. LAB file (CSV or CGATS; no transforms)	Read a file (CSV or CGATS format) containing Lab* data. The reference illuminant is assumed to be the same as the selected color space (D65 for sRGB, etc.). This is at variance with current practice, where Lab* files are assumed to have D50 data. The new LAB D50 file (below; Imatest 4.4+) is now recommended. A dialog box appears for entering the filename. CSV files consist of 24 lines with L, a, b* values on each line separated by spaces, commas (,), or semicolons (;). Example (first 3 lines of 24): 38.08, 12.09, 14.39 66.38, 13.22, 17.14 51.06, 0.38, -22.06 (The commas are optional if spaces are present & vice-versa.) If you have an Excel .CSV file with extra rows or columns, you can easily edit it Excel by selecting the key region (3 columns, 24 rows), copying it to a new file, and saving it in .CSV format. Lab* data is preferred to xyY data below because it is independent of white point color temperature, hence less error-prone. The CGATS file format is also supported.
5. xyY 5000K file, 6. xyY 6500K file, 7. XYZ 5000K file, 8. XYZ 6500K file	Read a file containing xyY or XYZ data with a 5000K (D50) or 6500K (D65) white point. Procedure and format is the same is the LAB data file, above. These are generally not recommended: they are kept for backwards compatibility.
9. Last file (none or file name)	Displays the last selected reference file (LAB, xyY, or XYZ). Select to read this file.
10. X-Rite default: pre-Nov 2014 D50 *(new in Imatest 4.4+)*	X-Rite Lab* D50 data for charts manufactured before November 2014, linked in the New color specifications…page, and still found on the X-Rite Colorchecker data page (as of March 2016) . Converts it to D65 for color spaces with a D65 white point (sRGB, etc.). Note that the RGB values obtained from this data do not agree with the values on the X-Rite page. Danny Pascale evidently ran into the same problem. Table 2 (top) of RGB coordinates… has two RGB columns, labeled sRGB (Pascale’s calculations) and sRGB (GMB) (from the X-Rite Colorchecker data page). ThesRGB column is in agreement with Imatest sRGB values.
11. X-Rite default: post-Nov 2014 D50 *(new in Imatest 4.4+)*	New X-Rite Lab* D50 data for charts manufactured after November 2014 from the New color specifications… page. Note that the CGATS files in these pages are in column-wise format, and can’t be read directly by Imatest. The post-November 2014 file uses commas (,) for decimal points.
4. LAB D50 file (CSV or CGATS) (new in Imatest 4.4+)	Read a file containing D50 Lab* data, and transform it if needed (using a Bradford Transform) to white point the selected color space’s white point. This is the recommended approach if you have spectrophotometer measurements for your individual chart. The CSV format is described above.

Reference file values can be

measured on your own instruments (instructions here),
derived from measured values from a camera you determine to be a “gold standard” by running Multicharts, then pressing File, Save L*a*b* results as CSV reference (making sure to check CSV reference file of L*a*b* results…). This can be useful for manufacturing testing because the camera under test is compared with attainable values rather then unattainable ideal values.
values you have determined to be “pleasing” that you wish to use as design targets. (Remember, accurate color is not necessarily pictorially pleasing. Designers of consumer cameras often aim for “pleasing” colors, which typically involves increasing saturation in foliage, skies, and skin.)

Color space: You can select among the following. Danny Pascale’s A Review of RGB Color Spaces is recommended for readers interested in an in-depth explanation of color spaces.

sRGB	The default space of Windows and the Internet. Limited color gamut based on typical CRT phosphors. Gamma = 2.2 (approximately), White point = 6500K (D65).
Adobe RGB (1998)	Medium gamut, with stronger greens than sRGB. Often recommended for high quality printed output. Gamma = 2.2, White point = 6500K (D65).
Wide Gamut RGB	Extremely wide gamut with primaries on the spectral locus at 450, 525, and 700 microns. One of the color spaces supported by the Canon DPP RAW converter. 48-bit color files are recommended with wide gamut spaces: banding can be a problem with 24-bit color. Gamma = 2.2, White point = 5000K (D50).
ProPhoto RGB	Extremely wide gamut. Gamma = 1.8, White point = 5000K (D50). Described in RIMM/ROMM RGB Color Encodings by Spaulding, Woolfe and Giorgianni.
Apple RGB	Small gamut. Used by Apple. Gamma = 1.8, White point = 6500K (D65).
ColorMatch RGB	Small gamut. Used by Apple. Gamma = 1.8, White point = 5000K (D50).
Rec. 709 Legal	Small gamut. Used in HDTV. Pixel values 16-235.
Rec. 709 Full	Same as Rec. 709 Legal, but with Pixel values 0-255.
ACES	Academy Color Encoding System, used in the workflow developed by the folks who bring you the Oscars. Extremely large gamut, covering all visible colors. Linear gamma. White point = 6000K.
Rec. 2020 Legal	Fairly large gamut, covering most colors from reflected objects. For UHDTV. Pixel values 16-235.
Rec. 2020 Full	Same as Rec. 2020 Legal, but with Pixel values 0-255.
DCI-P3	Medium gamut, similar to Adobe RGB. For digital projection systems.