Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1998-11-16
2001-04-24
Rogers, Scott (Department: 2624)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C358S451000, C382S252000
Reexamination Certificate
active
06222643
ABSTRACT:
BACKGROUND
1. Technical Field
The present invention relates generally to digital image printing; and, more particularly, it relates to probability error diffusion techniques applied to digital image printing systems.
2. Description of Prior Art
Conventional digital image printing systems commonly employ various methods of error diffusion to pixel intensity. Classic error diffusion generates a pseudo random pixel structure having intermediate levels of the pixel intensities. The intermediate level of a given pixel is adapted to the nearest intensity that can be generated using the available resources of the printing system. The difference between the actual pixel information and the nearest intensity that is chosen to print the pixel is recorded and this difference is an error to which the error diffusion method is applied. The error is spread or diffused over pixels adjacent to the pixel used in a predetermined mask.
Drawbacks of the classical error diffusion method when applied to the pixel's intensity include the fact that pixel intensity, when viewed within a certain spatial vicinity, are inherently coupled one to another. For example, the human eye integrates a group of the image data as a function of the intensity of the pixels in a near spatial vicinity to the pixel. The fact that the classic error diffusion method uses the pixel characteristic of intensity results in many deleterious visible effects and performance limitations. The pixel characteristic of intensity is intrinsically coupled to the pixels in the near vicinity of the pixel. The performance limitation of the classic error diffusion method stems primarily from the fact that is impossible to decouple the intensity characteristic of the pixel absent some additional image processing.
Further limitations and disadvantages of conventional and traditional systems will become apparent to one of skill in the art after reviewing the remainder of the present application with reference to the drawings.
SUMMARY OF THE INVENTION
Various aspects of the present invention can be found in an image processing system that converts a plurality of image data into a form suitable for reproduction. The invention takes in the plurality of data into the image processing and operates on the plurality of data to convert it so that it may be displayed or reproduced on, for example, a printing medium. When using paper as the printing medium, a printer deposits, for example, ink, wax, or some other marking medium on the paper. The marking medium leaves a visibly perceptible modification to the paper for viewing of the plurality of image data in a manner substantially similar to the actual and original representation of the plurality of image data.
In certain embodiments of the invention, the image processing system may be contained within a single function device or peripheral. In other embodiments, the image processing system may be contained within a multi-functional peripheral. The multi-functional peripheral is a peripheral device containing a plurality of internal devices wherein each of the devices operates either independently or cooperatively to process the plurality of image data.
Various other aspects of the present invention may be found in a method that employs error diffusion to a pixel placement probability that is generated using the image processing system. The pixel placement probability is generated directly using at least one characteristic of a pixel. In other embodiments, the pixel placement probability is generated through at least one intervening value wherein the at least one intervening value is calculated from the at least one characteristic of the pixel. The characteristic of the pixel may comprise an intensity value or chroma information of the pixel, depending on the embodiments. In certain embodiments of the invention, the at least one intervening value is a pixel ink density of the pixel.
The error diffusion may utilize a predetermined threshold mask to diffuse the error to pixels adjacent to the pixel. Alternatively, the predetermined threshold mask can be used to diffuse the error to pixels that are not immediately adjacent to the pixel. In either embodiment, the error is diffused to pixels contained within the plurality of image data.
Other aspects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
REFERENCES:
patent: 5663810 (1997-09-01), Kirk
patent: 5973803 (1999-10-01), Cheung et al.
Wong et al, “Entropy-Constrained Error Diffusion”, 1995 SID Digest, pp. 905-908.*
Robert W. Floyd and Louis Steinberg, “An Adaptive Algorithm for Spatial Greyscale”, Proceedings of the Society for Information Display, Symposium Digest of Technical Papers, vol. 17/2, Second Quarter, 1976, pp. 75-77.
Akin Gump Strauss Hauer & Feld L.L.P.
Conexant Systems Inc.
Rogers Scott
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