US 2003/0210409 A1 · PWM rendering for color/gray-scale text and graphics for laser printer

Abstract

The appearance of edges in an image is improved through precise placement of subpixels within pixel cells that are located on or near edges in an image. Image data is examined to identify a “target pixel” near the edge of an object that represents the object and is adjacent to a “background pixel” that represents only background. The target pixel may represent both the object and its background or it may represent the object only. A “second pixel”, adjacent to the target pixel and representing the object, is also identified. The second pixel may represent both the object and its background or it may represent the object only. The target pixel's location with respect to the second pixel is analyzed to determine the placement of a subpixel within the target pixel cell and the placement of a subpixel within the second pixel cell, such that the edge of the object is well-defined and the density of the object is preserved. A vertical smoothing process can additionally be performed to improve further the appearance of edges in the image. The technique is particularly advantageous for printing a halftoned object represented by pixels that are not saturated.

Claims24

Dependent claims

A method for processing image data for presentation by a printing device of an image that depicts an object in front of a background, wherein the method comprises:

obtaining a rendition value for a target pixel that represents the object and is adjacent to a background pixel that represents only the background, wherein the rendition value represents a degree to which the target pixel represents the object;
determining a first position value that represents a position of a subpixel within the target pixel, wherein the determination is based on the target pixel's location with respect to a second pixel that represents the object and is adjacent to the target pixel;
and
determining a second position value that represents a position of a subpixel within the second pixel, wherein the determination is based on the second pixel's location with respect to the target pixel.

1 more element

An apparatus for processing image data for presentation by a printing device of an image that depicts an object in front of a background, the apparatus comprising processing circuitry that:

obtains a rendition value for a target pixel that represents the object and is adjacent to a background pixel that represents only the background, wherein the rendition value represents a degree to which the target pixel represents the object;
determines a first position value that represents a position of a subpixel within the target pixel, wherein the determination is based on the target pixel's location with respect to a second pixel that represents the object and is adjacent to the target pixel;
and
determines a second position value that represents a position of a subpixel within the second pixel, wherein the determination is based on the second pixel's location with respect to the target pixel.

1 more element

A medium readable by a device embodying a program of instructions for execution by the device to perform a method for processing image data for presentation by a printing device of an image that depicts an object in front of a background, wherein the method comprises:

obtaining a rendition value for a target pixel that represents the object and is adjacent to a background pixel that represents only the background, wherein the rendition value represents a degree to which the target pixel represents the object;
determining a first position value that represents a position of a subpixel within the target pixel, wherein the determination is based on the target pixel's location with respect to a second pixel that represents the object and is adjacent to the target pixel;
and
determining a second position value that represents a position of a subpixel within the second pixel, wherein the determination is based on the second pixel's location with respect to the target pixel.

1 more element

An apparatus for processing image data for presentation by a printing device of an image that depicts an object in front of a background, wherein the apparatus comprises:

means for obtaining a rendition value for a target pixel that represents the object and is adjacent to a background pixel that represents only the background, wherein the rendition value represents a degree to which the target pixel represents the object;
means for determining a first position value that represents a position of a subpixel within the target pixel, wherein the determination is based on the target pixel's location with respect to a second pixel that represents the object and is adjacent to the target pixel;
and
means for determining a second position value that represents a position of a subpixel within the second pixel, wherein the determination is based on the second pixel's location with respect to the target pixel.

1 more element

Dependencies are inferred from the claim text.

PWM rendering for color/gray-scale text and graphics for laser printer

Life of this patent

PWM rendering for color/gray-scale text and graphics for laser printer

Life of this patent

Abstract

Claims24