A device color gamut, or simply gamut, is an indication of the range of colors which may be produced on an imaging system. The gamuts of different systems will be different. For example, most printing systems cannot produce colors as dark as those attainable on CRT displays, while most CRT displays cannot produce Cyans and Yellows as pure as those available with most CYMK inksets.
To further complicate matters, not all CMYK printing gamuts will be alike, nor will all CRT gamuts be alike. High-speed, high-volume magazine printing generally produces smaller gamuts than does commercial printing, so gamut depends upon market. Gamut also depends on other factors, such as colorant set, so using different inks in printing or different phosphors in monitors will influence the gamut. (In printing, the order in which the inks are printed will change the gamut, too!)
Color, as we know, is perceived three-dimensionally. A single two-dimensional plot of a gamut, by itself, does not convey sufficient information about a gamut.
A rectangular projection of a gamut onto the (a* b*) plane does have its place as one of several tools for evaluating gamuts. Far less useful are "gamuts" plotted in the CIE Chromaticity Diagram, which is visually non-uniform, and grossly magnifies the importance of darker chromatic colors -- the darker such colors get, the more distorted they become. (This is because chromaticity diagrams are distance-distorting affine projections of color space.) Such diagrams are useful only for specialized applications, such as illumination and video.
Gamuts are useful for answering many questions, particularly:
Gamut information may be represented in a number of ways, including:
Another thing to be wary of here are the number of samples from the gamut actually used to make the plot. All too frequently, such projection plots are made using only the colors Red, Green, Blue, Cyan, Magenta, and Yellow. Such hastily made plots, which are easily recognized because they look like irregular hexagons (line segments for sides), are nearly devoid of information. A well-made (a*, b*) projection plot will be produced using data from many gamut-limit colors, and will have curves between most, if not all, of the primaries.
Naturally, several slices in each orientation are necessary to get a reasonably complete feel for a gamut. You may wish to have hue slices for every 15 or 20 degrees, and lightness slices for every 5 or 10 units of L*.
Armed with a collection of these slices for two sets of conditions (same printer and paper, with different ink sets, for example), it is useful to overlay one on top of the other for comparison purposes.
We offer a standard service of gamut measurement, analysis, and evaluation. It is currently available for hard-copy devices, such as printers. As few as one or as many as a hundred (or more) combinations of devices, settings, inks, and papers may be measured, analyzed, and evaluated.
We provide you with a test target in digital form. The test target contains over 150 differently colored patches. You print the target under your choice of conditions, and send the printouts to us. We measure them and perform an analysis using our own state-of-the-art software. We return to you a report which specifies the volume of the gamut in CIELAB space, the proportion of colors in-gamut from a popular spot color formulation system, a 2-D projection of the gamut onto the (a*, b*) plane, a collection of hue and lightness slices, and a virtual gamut which you can view interactively.
Write us at firstname.lastname@example.org for pricing.
In order to get a feel for interactively exploring a 3-D virtual gamut solid, we have a free demo gamut page. Although the gamut solid it generates is nowhere near as detailed as from our pay service, it can help give you an idea of one of the more abstract elements of color gamut. You enter the CIELAB coordinates of the device White, Black, Red, Green, Blue, Cyan, Magenta, and Yellow, and a virtual gamut solid is returned to your browser.
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