Techniques Of Imperceptibly Altering The Spectrum Of A Displayed Image In A Manner That Discourages Copying

A recording on a physical media of a plurality of visual images, wherein

• the colors of individual recorded images are represented by relative values of a given number of more than three color components,
• the relative values of the given number of color components of the images are altered in a manner that is not perceptible to the human eye in reproductions of the images from the physical media, and
• the altered images are characterized by the alterations being perceptible to the human eye as degrading changes of colors in copies of reproductions of the images when the copies are represented by relative values of less than the given number of color components.

A method of altering visual images in a manner that discourages copying by a video camera having a spectral sensitivity different from the spectral sensitivity of the human eye, wherein:

• a spectral content of the individual visual images is altered in a manner that is metameric to the human eye, the alteration therefore being imperceptible to the human eye,
• the spectral content of the individual visual images is altered in a manner that is not metameric to the video camera when capturing the visual images, the alteration therefore being perceptible to the human eye with degrading changes in the color representation in copies of the altered images that are captured by the video camera.