Method of selective edge softening and rendering for the suppression of halo

• US 20050062995A1
• Filed: 11/10/2004
• Published: 03/24/2005
• Est. Priority Date: 12/06/1999
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Loce, Robert P., Cuciurean-Zapan, Clara
• Granted Patent: US 7,227,669 B2
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: G06K 15/1826 Object trapping
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 2207/30144 Printing quality
• CPC Class Codes: G06T 2207/30176 Document
• CPC Class Codes: G06T 5/30 Erosion or dilatation, e.g. thinning
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: H04N 1/4092 Edge or detail enhancement
• CPC Class Codes: H04N 1/58 Edge or detail enhancement; Noise or error suppression, e.g. colour misregistration correction H04N1/62 takes precedence

Abstract

Selective edge softening and selective edge dithering is introduced into an image representation to improve local control where halo problems are expected. Selective areas of dilation are isolated and separately dithered or halftoned, the result of which is then swapped back into or substituted for the stored original image. In this manner misregistration and color plane-to-plane interactions can be compensated for in plural image forming station architecture systems. The same technique is also valuable in monochrome systems as an aid to overcoming edge displacement and slow toner problems when the selective edge softening is selectively applied to edges which are in particular perpendicular to the fast scan direction.

Claims

1. A method for eliminating halo defects in a print image, comprising:

receiving and storing print image data;

selectively dilating a copy of the stored print image data to create an area of selective dilation; and

,

halftoning the area of selective dilation.

2. The method of claim 1, wherein the dilating step is applied only to an edge of a black region.

3. The method of claim 1, wherein the dilating step is applied to an edge of a color region.

4. The method of claim 1, wherein the dilating step is applied to an edge of a color region if there is a subsequent color to be developed.

5. The method of claim 1, wherein the dilating step is applied only to an edge perpendicular to a fast scan direction.

6. The method of claim 1, wherein the dilating step is applied only to an edge perpendicular to a slow scan direction.

7. The method of claim 1, further comprising the step of edge softening the area of selective dilation.

8. The method of claim 7, wherein the halftoning applied to the area of selective dilation is at a higher frequency than the halftoning applied to the rest of the image.

9. The method of claim 7, wherein the halftoning applied to the area of selective dilation is of a diffused type.

10. The method of claim 7, wherein the halftoning applied to the area of selective dilation is of a stochastic type.