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Click on the following links to go to the thumbnails below,
then click on a thumbnail to see a full size image.
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Features,
Detailed specs / System requirements
Windows 7 Mac OS X
BabelColor CT&A main screen. The blue
color patch corresponds to Space #1, and the green color patch to
Space #2. The color patches are converted from the selected RGB space to the
selected display profile (the default display ICC profile in this case). We see
a small triangle in the bottom of the blue patch (bottom-left of the
screenshot); this indicates that the color is clipped by the display profile,
i.e. that the displayed color is not exact. For the screen shown above,
the Space #1 color patch is converted, for display purposes only, from Adobe (1998) to
the display profile; the Space #2 color patch is converted from sRGB to
display profile.
The Space #2 list box is opened, and Custom space
highlighted. The space selection list is identical in Space #1. The main screen
has been extended to show additional patch layouts. In the bottom-left, we see
larger patches presented side by side; you can select a gray, white or black
background by just clicking on the patches. In the top-right, we see the patches
on different backgrounds simultaneously. In the bottom-right, we see text of
each color on black and white backgrounds, as well as on a background of the
other color; the text content and style can be edited.
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Density tools
Metamerism tools RAL
DESIGN tool
Graph tools Graph tools (saved image)
ISO 3664+ (Illumination analysis) ISO report
(Illumination)
ISO 3664+ (Monitor analysis)
ISO report (Monitor) ISO 12646
target
Whiteness tools
Whiteness tools (saved image)
Click on a thumbnail for a full size image and descriptive
text. To have a look at all Spectral tools, first click on the "Density tools"
thumbnail, then select "Next screen" in the full view page that opens. top
Compare Mac (Apple RGB) to Windows (sRGB)
The same RGB coordinates entered in Apple RGB (the default
RGB space in older Macs) on the LEFT side (Space #1) and sRGB (Windows default
RGB space, and Mac default space since OS X 10.4) on the RIGHT side (Space #2). You can see on the chromaticity diagram that the
same RGB coordinates correspond to two different colors (i.e. they have
different "xy" coordinates). In essence, the darker
sRGB color patch shows how a color generated on a Mac a few years ago, will look on a
recent Mac or in a Windows PC if it is not properly translated to the sRGB environment.
A similar effect will be seen for all colors in legacy images generated in Apple
RGB, which were most likely not tagged with an ICC profile. The
CIE94 color difference is 5,51, a very noticeable difference. The difference
is mostly intensity (DeltaL* = -5,25), followed by chroma (i.e. saturation;
DeltaC* = 3,91), and some hue difference (DeltaH* = 2,21).
The patch layout on the right of the main screen shows the two
colors against a background of the other patch color, and against black,
mid-gray, and white backgrounds.
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A color conversion from Space #2 to Space #1. The spaces have
different primaries as well as different illuminants; still, BabelColor CT&A can
determine the exact match. Notice that the CIEDE2000 color difference
is zero; since the illuminant is different, both spaces coordinates are
converted to D50 in order to obtain a valid color difference value. In the
chromaticity diagram, you will notice that the "xy" coordinates are
different but this is expected since the illuminants are also different.
BabelColor CT&A determines the equivalent color when viewed relative to the other space
illuminant. top
L*a*b* D50 input in Adobe (1998), converted to sRGB. In this
example, L*a*b* values had been determined relative to illuminant D50. We want
to convert them to sRGB and also get the equivalent Munsell Hue, Value and
Chroma (HVC). Because our L*a*b* values were determined relative to D50, we need
to check the "L*a*b* / L*u*v* in
D50" radio button under the L*a*b* display; please note that we would
not check this button to input D65 L*a*b* values since the Adobe (1998) space is
based on a D65 Illuminant. The Adobe (1998) space was selected because the input
color is within the space gamut; this can be easily checked since an
out-of-gamut input will automatically be flagged by exclamation points over the
RGB data displays while entering the L*a*b* values.
We obtain Munsell 4.1G 5.6/14.4, which is not the
closest standard Munsell patch that we would get in a Munsell Book of Colors (or
in BabelColor CT&A even larger Munsell
Color Deck), but a more precise equivalent, with fractional accuracy.
As we see in the
chromaticity diagram the color,
represented by the green square, is outside of the sRGB gamut and clipping has occurred for the
red coordinate. On the RIGHT side, a red exclamation point ( !
) appears over the corresponding display box of Space #2. The clipping error is
8,62 CMC(1:1); the error can also be evaluated using the other formulas
shown in the opened list box. There is another (green) exclamation point (
! ) in the larger color patch, indicating that
the Space #1 color cannot be exactly represented by the currently selected
display profile.
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Munsell 7,5BG 4/8 color chip (from
the Munsell Color Deck) being converted to a RGB space, first sRGB, then
Adobe (1998).
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R'G'B' input in Adobe (1998) converted to the FED-STD-595B
Color Deck (we can also convert FROM a
Color Deck). We see that this is not an exact match, and the closest FED-STD
chip is #14255, as represented by the square patch in the center of the L*C*h*
pad, with a 2,26 CIEDE2000 error. The patches around the center one show the NEXT best
matches in terms of closeness in saturation (+/- sat., i.e. chroma),
luminosity (+/- lum., i.e. lightness), and hue; their IDs can be
obtained by resting the mouse cursor over the patch until a popup tag appears
(as shown above for the + sat. patch). Depending on the end use for the
matched color, the match could be acceptable or not. To help make this decision,
we can see if the difference is noticeable when we separate the two colors. When
you click on the patches on the bottom of the display, you cycle through
different patch layouts with various background colors and patch sizes. The
layout shown above-right consists of two small patches separated by a gray
background; the difference between the patches is much less perceptible, and
this match could well be satisfactory for some uses where the matched color is
not seen near or against the reference color.
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Additional graphical data can be superimposed on the CIE1931 chromaticity diagram.
The above image shows the Planckian locus for blackbodies with temperatures
between 1 000 K and 25 000 K. GretagMacbeth/X-Rite ColorChecker chart patches as
computed for illuminants C, D50, or D65 can also be shown, as well as the gamut
of SWOP coated. The position of the mouse, in chromaticity coordinates, is shown
in the small white box.
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A custom RGB space can be defined by specifying the illuminant
coordinates, the red, green and blue primaries, and the gamma function. A
D-series or blackbody illuminant can be defined simply by entering
the source temperature, in kelvin. Gamma can be defined by a single
parameter or a two segment function with a slope for the linear portion, a
transition, an offset, and a gamma value. You can also export all the custom
data as well as the XYZ-to-RGB and RGB-to-XYZ matrices
coefficients to a spreadsheet. top
This table contains
information on the parameters used internally by BabelColor CT&A to
compute the displayed data. The table shown above contains the space's
primaries, its illuminant, and the gamma parameters of the
eciRGB_v2 space (Note: The detailed gamma parameters are, in effect, the
parameters of the L*, i.e. L-star, tone response curve). Other
tables are available for the illuminants' coordinates, the RGB to XYZ
and XYZ to RGB conversion matrices, and for the Bradford matrices
used to convert XYZ coordinates between different illuminants (i.e. chromatic
adaptation). top
Windows 7
PDF (shown on Mac OS X)
A complete help manual is provided. It contains a detailed description of the
features and the interface, a thorough theoretical presentation, with equations,
of the various conversion processes within BabelColor CT&A, and tutorials with
an emphasis on practical uses. The thumbnail on the left shows the manual in the
HTML Help help application format found in Windows; it is fully indexed and
searchable. The PDF manual, shown on the right on a Mac, is fully hyper-linked; the file has an index, and is searchable. Both manuals can be
printed. top | 
BabelColor