Color
Rendition Chart (X-Rite ColorChecker) 24 colour Chart
The
ultimate goal of any process of photography, electronic publishing,
printing, or television is to reproduce all colors perfectly. However,
color rendition is a very subjective matter.
To
help make meaningful judgments about color rendition, a totally
non-subjective standard of comparison is needed. The ColorChecker chart
provides the needed standard with which to compare, measure and analyze
differences in color reproduction in various processes.
The
ColorChecker is a checkerboard array of 24 scientifically prepared
colored squares in a wide range of colors. Many of these squares
represent natural objects of special interest, such as human skin,
foliage and blue sky. These squares are not only the same color as
their counterparts, but also reflect light the same way in all parts of
the visible spectrum. Because of this unique feature, the squares will
match the colors of natural objects under any illumination and with any
color reproduction process.
The
ColorChecker chart provides an easy way to recognize and evaluate the
many factors that can affect color reproduction. To evaluate the effect
of varying any given factor, simply compare the chart´s color
image as it appears on the photograph, television picture, computer
monitor, or printed sample - with the actual ColorChecker. This
comparison may be made visually or through optical density measurements.
The
ColorChecker is proportioned so individual squares are large enough to
be measured with a densitometer. Many variables may influence the kind
of light reflected by the ColorChecker. These include the spectral
nature of the light sources and of nearby objects that may reflect
light toward the chart or otherwise affect the illumination. Also,
camera lenses may be slightly colored, or may gather stray light from
outside the ColorChecker. The type of film, equipment, processing, and
(in graphic arts reproduction) printing ink may likewise affect color
rendition. Even the very appearance of the ColorChecker and its imaged
copy may be influenced by viewing conditions.
We
mention these variables so that when you use the ColorChecker, you will
be aware of them and take steps to control them. In this way, you will
be able to know which differences in color rendition can be ascribed to
which parts of your system. Clearly, you may need to make a number of
controlled test to account for the unintentional variations in process.
Applications:
Photography
1. Photograph
the ColorChecker chart using color print film under two different types
of illumination to produce color prints. Compare the images (or the
measured reflection densities of corresponding areas on the prints) to
evaluate the effect of changing illumination. Repeat the process using
various filters.
2. Do
the same as in # 1 above, but use two different types of transparency
film. Compare the slides visually or use a densitometer to compare the
transmission densities of corresponding areas.
3. Photograph
the ColorChecker chart using two different types of color film. Then
compare the slides or prints to the ColorChecker. For critical
comparison, standardized lighting, as found in X-Rite lighting
products, should be used. Slides should be viewed on a standard
transparency viewer and prints should be illuminated by a 5000K light
source. The slides and prints can also be compared by using a
densitometer.
Graphic Arts
1. Make
color separations and plates of the ColorChecker chart. Print
ink-on-paper copy of the ColorChecker chart. Compare the copy to the
original chart under standard viewing conditions, or compare the
measured reflection densities using a densitometer.
2. With
this information, you can now make the necessary adjustments for your
color separation and/ or printing process.
Electronic Publishing
1. Make
a scan of the ColorChecker using the default settings of your scanning
software. Open scanned image in your image editing or scan utility
software, then measure and record the RGB values for each patch in the
ColorChecker image.
2. Compare
these readings with those from a “pure” digital
TIFF file of the ColorChecker or from the table below. Calculate and
record the differences.
3. With
this information, you can create a characterization profile in either
your image editing software or scan utility software. This can be used
to adjust all future scans to compensate for the characteristics of
your scanner.
Television
1. Frame
the ColorChecker chart with a video camera and adjust several control
monitors to display the chart identically.
2. View
the ColorChecker chart with several video cameras (making sure the
lighting is always the same). Display the pictures on the balanced
monitors and adjust the cameras to make all of the monitors match as
closely as possible. The residual differences in color rendition will
be displayed on the monitors.
Technical Data
Color
names and specifications are given in the table below. The Munsell
notations (which describe color in terms of hue, value, and chroma) are
widely used by artists, designers and color technologists. The ISCC-NBS
names are designated by a method established by the Inter-Society Color
Council and the National Bureau of Standards of the USA. The assigned
names are either names of natural objects spectrally simulated, names
of additive primaries (red, green, and blue) and subtractive primaries
(cyan, magenta, and yellow), Munsell names (for the gray series), or
abbreviated ISCC-NBS names. A more in-depth technical description of
the chart can be found in the article “A Color Rendition
Chart” by C. S. McCamy, H. Marcus and J. G. Davidson, Journal
of Applied Photographic Engineering, Summer Issue 1976, Vol. 2, No. 3,
pg. 95-99.
Note: The
user should be careful to avoid touching the colored squares of the
ColorChecker chart with fingers or objects that might mar or soil the
colors. Avoid exposing the ColorChecker chart to light, except when it
is in use. Also avoid exposing it to high temperature, high humidity
and chemical fumes. Depending on use, it is recommended that you
replace your ColorChecker chart every two years to ensure correct color
identification.
Color Rendition Chart (X-Rite ColorChecker)
Scan Reference Chart
Universal
Test Target
Critical
Flesh Tones Test Chart
Bar Test Chart(IEC 61146)
White Balacing Test Chart
ISO 12233:2014 Edge SFR(eSFR)Test chart
Color Spilled Coins (Dead Leaves) Test Chart
Gray Scale Test Chart(11 steps)
Streaking Measurement Test Chart
Color Bar Test Chart
Gray scale chart
Grid Test Chart
ISO 12233 Enhanced digital camera resolution chart
Standard SFRplus Chart
SFRplus Chart on Photographic Paper QI-SFR10-P-RM
ITE Grayscale Chart II(Gamma = 1)
Black & White Spilled Coins (Dead Leaves) Test Chart
OECF Test Chart (ISO 14524)
ISO 12233: 2014 (eSFR)Photographic chart
ISO-14524 digital camera contrast chart
ISO-15739 digital camera noise test chart
ISO 12233 Digital still-camera resolution chart
Automotive Test Chart
SFRplus Chart: Inkjet on Paper - 4:1 Contrast Ratio
SFRplus Chart: Inkjet on Paper - 10:1 & 2:1 Contrast Ratio
Distortion Grid Test Chart
HDTV Gray Scale Test Chart
ITE Grayscale Chart I(Gamma = 0.45)
EIA RESOLUTION CHART 1956
Sector Star Test Chart (72 cycles)
Sector Star Test Chart (36 cycles)
HDTV Universal Test Chart
DTV Color Rendition Test Chart
36-Patch Dynamic Range Test Chart
Spectrometer
OHSP-350
OHSP350A Light
Spectrometer
HPL-200
Flicker illuminometer
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