The ColorChecker Chart is a chart containing 24 coloured patches arranged in a 6 by 4 array. It measures approximately 280 mm by 216 mm (11 inches by 8.25 inches). [A previous version was larger, approximately 330 mm by 230 mm (13 inches by 9 inches).] There's also a “Mini ColorChecker Chart,” pocket size, measuring approximately 83 mm by 57 mm (3.25 in by 2.25 in).
The chart is commonly called “Macbeth,” owing to its original developer and manufacturer. Macbeth does not have a capital B.
The chart is described in this paper [BibTeX record]:
McCamy, C.S., Marcus, H., and Davidson, J.G., "A Color Rendition Chart," Journal of Applied Photographic Engineering 11(3) (Summer issue, 1976), 95-99.
The image above is taken from a former Gretag page; its RGB values aren't to be trusted. (For example, the grayscale series has a noticeable purple tinge.) Contact me if you'd like accurate RGB values (contact details are on my home page).
There used to be a “Digital ColorChecker (DCC).” It turned out to be unreliable; it's now discontinued. There's a a “Digital ColorChecker Semi Gloss (SG)”; it offers 140 colour and grey patches, including (near the centre) the original 24 ColorChecker patches.
Here's a subtlety concerning colour reproduction. Everyone documents the colours that are produced from the chart under whatever illuminant you use. But imaging systems almost invariably introduce tone and colour mapping to make images look right when displayed (as is usually the case) much less bright and with lower contrast ratio than is typical at capture. When captured or reproduced, the luminance and chromaticity values should not be expected to match the camera's or scanner's stimuli! For more about this, see Perceptual uniformity, picture rendering, image state, and BT.709.
X-Rite does not publish spectral reflectance data for the ColorChecker. (Spectral data is however available from Gretag for its big brother, the ColorChecker DC.) The ColorChecker used to come with an insert sheet containing colorimetric data, referenced to Illuminant C. I have entered, checked, and double-checked the data on that sheet. The Hue, Value, and Chroma columns are in Munsell notation. (I made a minor editorial change: I indicate Munsell chroma value of zero for the grayscale patches.)
|1||dark skin||0.400||0.350||10.1||3 YR||3.7||3.2||moderate brown|
|2||light skin||0.377||0.345||35.8||2.2 YR||6.47||4.1||light reddish brown|
|3||blue sky||0.247||0.251||19.3||4.3 PB||4.95||5.5||moderate blue|
|4||foliage||0.337||0.422||13.3||6.7 GY||4.2||4.1||moderate olive green|
|5||blue flower||0.265||0.240||24.3||9.7 PB||5.47||6.7||light violet|
|6||bluish green||0.261||0.343||43.1||2.5 BG||7||6||light bluish green|
|7||orange||0.506||0.407||30.1||5 YR||6||11||strong orange|
|8||purplish blue||0.211||0.175||12.0||7.5 PB||4||10.7||strong purplish blue|
|9||moderate red||0.453||0.306||19.8||2.5 R||5||10||moderate red|
|10||purple||0.285||0.202||6.6||5 P||3||7||deep purple|
|11||yellow green||0.380||0.489||44.3||5 GY||7.1||9.1||strong yellow green|
|12||orange yellow||0.473||0.438||43.1||10 YR||7||10.5||strong orange yellow|
|13||blue||0.187||0.129||6.1||7.5 PB||2.9||12.7||vivid purplish blue|
|14||green||0.305||0.478||23.4||0.25 G||5.4||8.65||strong yellowish green|
|15||red||0.539||0.313||12.0||5 R||4||12||strong red|
|16||yellow||0.448||0.470||59.1||5 Y||8||11.1||vivid yellow|
|17||magenta||0.364||0.233||19.8||2.5 RP||5||12||strong reddish purple|
|18||cyan||0.196||0.252||19.8||5 B||5||8||strong greenish blue|
|20||neutral 8||0.310||0.316||59.1||N||8||0||light gray|
|21||neutral 6.5||0.310||0.316||36.2||N||6.5||0||light medium gray|
|22||neutral 5||0.310||0.316||19.8||N||5||0||medium gray|
|23||neutral 3.5||0.310||0.316||9.0||N||3.5||0||dark gray|
You can access the table in tab-separated-value (tsv) format (1414 bytes). If you import this file to Excel (v.X, at least), it will silently take the Munsell hue "5 P" of purple and replace it with 5:00 PM or 17:00:00 or some such (!), and it will silently delete trailing zeros in numeric quantities.
Macbeth was once its own company; it was acquired by Kollmorgen Corporation, which was (I guess) acquired by Gretag, who then started calling themselves GretagMacbeth (spelled all in one word), who merged with X-Rite, and the company is (at the date of writing) called X-Rite. ColorChecker is one word (not Color Checker, and not Colour Checker).