Print enhancement system for enhancing dot printer images

Abstract

A method and apparatus for enhancing the quality of images printed by dot printers or dot displays are disclosed. Image irregularities caused by quantization are smoothed by using a set of rules to transform an initial pattern into an enhanced pattern for printing. The initial pattern may consist of a matrix of bits representing an image having X dots per inch along an intended direction of printing. An intermediate pattern is formed by replicating columns of bits from the initial pattern. Image enhancement rules are applied to the intermediate pattern to invert one or more bits in the intermediate pattern to create an enhanced pattern. The enhanced pattern is printed at n*X dots per inch along the direction of printing where n> / =1.

Description

FIELD OF THE INVENTIONThis invention relates to dot printers or other types of dot display systems, and more particularly, to a method and apparatus to enhance the quality of images printed by dot printers or otherwise displayed by dot display systems.BACKGROUND OF THE INVENTIONDot printers produce a printed image by depositing a pattern of individual dots of ink upon a recording medium, such as a sheet of paper. Ideally, if the individual dots are sufficiently small and closely spaced, only the overall image, and not the individual dots, are perceived by the human eye.However, depending on the relative size of the smallest detail of the overall image and the size of the individual dots, certain irregularities may be perceived due to the discrete nature of the dots and due to the inherent nature of the printing process. For example, undesirable stepping (quantization) and jagged edges are generally apparent when the image consists of a diagonal line at a slight angle to the print di...

AI Technical Summary

Benefits of technology

A print image enhancement system according to this invention enhances the quality of images printed by dot printers or otherwise displayed by dot display systems. In the preferred embodiment, the print image enhancement system resides in a dot printer. The print image enhancement system effectively smoothes out noticeable quantization in the dot pattern by using a set of rules to transform an initial dot (or bit) pattern into an enhanced pattern. The printed image is generated by printing the enhanced pattern.

Problems solved by technology

However, depending on the relative size of the smallest detail of the overall image and the size of the individual dots, certain irregularities may be perceived due to the discrete nature of the dots and due to the inherent nature of the printing process.

For example, undesirable stepping (quantization) and jagged edges are generally apparent when the image consists of a diagonal line at a slight angle to the print direction, or a diagonal line at a steep angle to the print direction.

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