Abstract: Engine response curves (RCs) can be used for streak compensation for printed documents. A feedback control paradigm can be included to effect RC compensation. Singular Value Decomposition (SVD) can be used to represent each RC in the collection of spatial RC data as a linear combination of basis vectors. RCs are approximated by selecting the first few basis vectors, the approximation aiding in noise rejection and reducing computation in the controller by reducing dimensionality of the RC data from gray levels to the number of SVD bases selected. An optimal subset of RCs is selectable from the set of approximated RCs by clustering the SVD weights, the clustered SVD weights producing TRCs that span all engine response RCs generated by a printer. Compensation RCs are constructible using reduced number of bases and clustered SVD weights.

Abstract: Methods and apparatus for spectrally-encoding plural source images and for providing the spectrally-encoded plural source images in a composite image, for rendering the composite image in a physical form, or for recovering a normalized version of an encoded source image from the rendered composite image such that the recovered source image is made distinguishable as a normalized color image.

Abstract: Methods and apparatus for spectrally-encoding plural source images and for providing the spectrally-encoded plural source images in a composite image, for rendering the composite image on a substrate, or for recovering at least one of the encoded source images from the rendered composite image such that the recovered source image is made distinguishable. The rendered composite image includes at least a first source image that is encoded and rendered with use of a selected colorant so as to be visually discernible on the substrate during a plurality of modes of intended illumination as a “background” image, and a second, “narrow band” source image that is encoded in the composite image so as to be recovered when illuminated by at least a selected of the plurality of modes of intended illumination that employs complementary narrow band illuminant.

Abstract: Methods and apparatus for spectrally-encoding plural source images and for providing the spectrally-encoded plural source images in a composite image, for rendering the composite image in a physical form, or for recovering at least one of the encoded source images from the rendered composite image such that the recovered source image is made distinguishable. Source image confusion in a rendered composite image is controlled by application of a illuminant-neutral gray component replacement (GCR) technique to the darkness common to the different colorants under the multiple illuminants.

Abstract: Methods and apparatus for spectrally-encoding plural source images and for providing the spectrally-encoded plural source images in a composite image, for rendering the composite image in a physical form, or for recovering at least one of the encoded source images from the rendered composite image such that the recovered source image is made distinguishable. A noise component is introduced in the encoding of the plurality of source images so as to mask at least one of the source images during spectral demultiplexing.

Abstract: Methods and apparatus for spectrally-encoding plural source images and for providing the spectrally-encoded plural source images in a composite image, for rendering the composite image in a physical form, or for recovering at least one of the encoded source images from the rendered composite image such that the recovered source image is made distinguishable. Source image confusion in a rendered composite image is controlled by application of a multi-illuminant gray component replacement (GCR) technique to the darkness common to the different colorants under the multiple illuminants.

Abstract: Methods and apparatus for spectrally-encoding plural source images and for providing the spectrally-encoded plural source images in a composite image, for rendering the composite image in a physical form, or for recovering at least one of the encoded source images from the rendered composite image such that the recovered source image is made distinguishable. The composite image is generated using an image-dependent dynamic range determination so as to provide a maximum usable contrast in a recovered source image.

Abstract: Methods and apparatus for spectrally-encoding plural source images and for providing the spectrally-encoded plural source images in a composite image, for rendering the composite image on a substrate, or for recovering at least one of the encoded source images from the rendered composite image such that the recovered source image is made distinguishable. The rendered composite image includes at least a first source image that is encoded and rendered with use of a selected colorant so as to be visually discernible on the substrate during a plurality of modes of intended illumination as a “background” image, and a second, “narrow band” source image that is encoded in the composite image so as to be recovered when illuminated by at least a selected of the plurality of modes of intended illumination that employs complementary narrow band illuminant.