1. A method for modeling the pixel elements of a dynamically varying color reproduction device from output image pixels generated in response to a test target, including steps of: producing an output image with the device in response to an input signal from the test target wherein the test target comprises a plurality of pixels; measuring with a sensor an output signal representative of the output image corresponding to a target preselected color; and constructing a linear state-space model of color producing behavior for a single pixel including a matrix characterization of the color reproduction device, wherein the matrix characterization represents a gradient of change of a plurality of color sensitivity function is s represented as a Jacobian matrix , the gradient is with respect to the input signal for the measured output signal at a nominal set of measured output values , and the gradient is predetermined as linear about the nominal values, wherein the state-space model represents the color reproduction device operation in terms of a derivative function between device input and output as: 
 y(k+1) x(k+1) =BV (K) (k) +X 0 where k is an iteration number, X 0 are L*, a*, b* values for a nominal CMY values, and, χ = [ L * a * b * ] , V = [ ∂ C ∂ M ∂ Y ] , B = [ ∂ L * ∂ C ∂ L * ∂ M ∂ L * ∂ Y ∂ a * ∂ C ∂ a * ∂ M ∂ a * ∂ Y ∂ b * ∂ C ∂ b * ∂ M ∂ b * ∂ Y ] ⁢ ⁢ χ o = [ L * a * b * ]. values for nominal CMY.