Note that a color printer cannot reproduce all the colors visible on a color monitor. The CIE LUV color space is designed with perceptual uniformity in mind.Ĭolor Gamuts The chromaticity diagram can be used to compare the "gamuts" of various possible output devices (i.e., monitors and printers).
The CIE XYZ color space and the CIE chromaticity diagram are not perceptually uniform, as the following figure illustrates. For example, color E in the above figure.Ī color space in which the distance between two colors is always proportional to the perceived distance. color B in the above figure is the dominant wavelength for color A.Ĭolors not having a dominant wavelength. The spectral color which can be mixed with white light in order to reproduce the desired color. For example, colors on segment CD are complementary to the colors on segment CB. It is defined by a color temperature of 6774 K.Ĭolors which can be mixed together to yield white light. It can therefore also provide the CIE xyz tristimulus values.Ī standard for white light that approximates sunlight. Giving one of the following chromaticity diagram.Ī device to measure the spectral energy distribution. This is commonly done by projecting the 3D color space onto the plane X+Y+Z=1, yielding a CIE chromaticity diagram. The weights X,Y,Z form the three-dimensional CIE XYZ space, as shown below.ĬIE Chromaticity Diagram Often it is convenient to work in a 2D color space. If we are given a spectrum and wish to find the corresponding X, Y, and Z quantities, we can do so by integrating the product of the spectral power and each of the three matching curves over all wavelengths. This is shown on the graph by having its intensity, R, take on a negative value.ĬIE Color Space In order to achieve a representation which uses only positive mixing coefficients, the CIE ("Commission Internationale d'Eclairage") defined three new hypothetical light sources, x, y, and z, which yield positive matching curves: A problem exists, however, because sometimes the red light needs to be added to the target before a match can be achieved. The scheme above can tell us what mix of R,G,Bis needed to reproduce the perceptual equivalent of any wavelength. Note that the phosphours of color TVs and other CRTs do not emit pure red, green, or blue light of a single wavelength, as is the case for this experiment. In order to define the perceptual 3D space in a "standard" way, a set of experiments can (and have been) carried by having observers try and match color of a given wavelength, lambda, by mixing three other pure wavelengths, such as R=700nm, G=546nm, and B=436nm in the following example.
: in the lecture on Diplays devices, we insisted on the particulate aspect of light (photon emission). Color Gamuts The RGB Color Cube Color Printing Color Conversion Other Color Systems RGB-Based Color Spaces HSV, HLS and HS Gamma Correction What is Gamma Correction? Cumulative effect of each of the gamma steps Gamma Correction and Color Space Alpha True-Color Frame Buffers Indexed-Color Frame Buffers Slide 1 : Color TopicsColor Topics in Computer GraphicsĬolor Topics in Computer Graphics Intro Elements of Color Visible Spectrum The Eye The Fovea The Fovea (2) Color Perception Color Matching CIE Color Space CIE Chromaticity Diagram A few definitions. Computer Graphics : Colors Computer Graphics Lectures Notes : Colors