A method for choosing visual characteristics of a characteristic space within a region includes calculating a mean characteristic of the region, determining a covariance of the region, inverting the covariance to produce an inverse covariance, estimating a target characteristic, determining a difference between the mean characteristic and the target characteristic transposing the difference to produce a difference transpose, determining a saliency from a product of the difference transpose multiplied by the inverse covariance multiplied by the difference, comparing the saliency to an acceptance criterion to yield one of an acceptance if the saliency satisfies the acceptance criterion and a rejection otherwise, adjusting the target characteristic and repeating the determining a difference, transposing the difference, determining a saliency and comparing the saliency steps if the comparing yields the rejection, and outputting the target characteristic if the comparing yields the acceptance.