Exact reproduction of colored images

Abstract

The problem of producing a colored image from a colored original is analyzed. Conditions are determined for the production of an image in which the colors cannot be distinguished form those in the original by a human observer. If the final image is produced by superposition of controlled amounts of colored lights, only a simple linear transform need be applied to the outputs of the image sensors to produce the control inputs required for the image generators. In systems which depend instead on control of the concentration or the fractional area covered by colored dyes, a more difficult computation is called for. This calculation may for practical purposes be expressed in table lookup form. The conditions for exact reproduction of colored images should prove useful in the design and analysis of image processing systems whose final output is intended for human viewing. Judging by the design of some existing systems, these rules are not generally known or adhered to. Modem computational techniques make it practical to tackle this problem now. Adherence to design constraints developed here is of particular importance where colors are to be judged when the original is not directly accessible to the observer as, for example, when it is on another planet.

G-Channel Restoration for RWB CFA with Double-Exposed W Channel

“…Moreover, the lack of an RB color signal decreases the SNR, which corresponds to an increase in the noise level and a decrease in the color fidelity of the generated color signal. Moreover, converting RWB to RGB through the use of a color correction matrix (CCM) results in the false color problem [ 13 , 14 ].…”

“…Owing to the fact that the W pixel includes the RGB spectral band, the spectral information of the R and B bands must be eliminated in order to accurately extract the G-channel information from the W-pixel values. A straightforward method for mapping the RWB values to RGB values involves the use of a linear transformation in the form of a 3 × 3 matrix , satisfying [ 14 ] where is a 3 × n matrix of the RGB color vector under a canonical illuminant and is a 3 × n matrix of the observed color vector of the RWB sensor responses (preferably under the same illuminant). The natural number n is the number of color samples.…”

Set theoretic estimation for problems in subtractive color

“…This space is called the human visual subspace (HVSS). 4,1,5,18 In normal human observers, the spectral sensitivities of the three cones are linearly independent, so the HVSS is a 3-dimensional subspace of the N-dimensional spectral space. While the final perception of color depends on nonlinear processing of the retinal responses in the neural pathways and the brain, to a first order of approximation, the sensation of color (under similar conditions of adaptation) may be specified by the responses of the cones.…”

A physical approach to color image understanding

“…Substituting these terms into equation (I), we obtain the Dichromatic Reflection Model equation: The model thus describes the light that is reflected from an object point.as a mixture of two distinct spectral power distributions, c,(X) and cb(X), each of which is scaled according to the geometric reflection properties of surface and body reflection. In the infinitedimensional vector space of spectral power distributions (each wavelength defines an independent dimension in this vector space [15,29]), the reflected light can be described as a linear combination of the two vectors c,(X) and cb(X).…”