Method of separated color foreground and background pixel improvement

• US 6,701,009 B1
• Filed: 06/06/2000
• Issued: 03/02/2004
• Est. Priority Date: 06/06/2000
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Chang, William Ho, Makoto, Otsu
• Primary Examiner(s): Patel, Jayanti K.
• Assistant Examiner(s): SUKHAPHADHANA, CHRISTOPHER T
• Application Number:
  US09/588,848
• Time in Patent Office: 1,365 Days
• Field of Search: 382/167, 382/162, 382/164, 382/165, 382/173, 382/176, 382/180, 382/199, 382/200, 382/205, 382/224, 382/266, 382/269, 358/1.1, 358/1.9, 358/2.1, 358/3.01, 358/3.27, 358/448, 358/462, 358/464, 358/518, 358/521, 358/530, 358/531, 358/532, 358/534, 358/535
• US Class Current: 382/164
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/194 involving foreground-background segmentation
• CPC Class Codes: H04N 1/58 Edge or detail enhancement; Noise or error suppression, e.g. colour misregistration correction H04N1/62 takes precedence

Abstract

A method for separating foreground and background image pixels from other pixels. The method determines if a current pixel is an edge pixel, and then selects a window of pixels surrounding the current pixel if it is on an edge. This window is then analyzed to produce a classification of a gradient field within the window, and defines foreground and background image pixel values depending upon the classification. Once foreground and background pixel positions are defined, the process interpolates the value for the current pixel. The accurate designation of foreground and background pixels eliminates or mitigates any color misregistration error in the pixel value.

Claims

1. A method for separating foreground and background image pixels, the method comprising:

determining if a current pixel is an edge pixel by comparing a gradient between the current pixel and at least one neighbor pixel to a threshold;

if the pixel is an edge pixel, selecting a window of pixels surrounding the current pixel;

analyzing the window to produce a classification from a classification set of a gradient field within the window, wherein the classification set comprises monotonic, similar vertex, one vertex, shifted vertex, and inverted vertex;

defining foreground and background image pixel positions depending upon the classification; and

interpolating a value of the current pixel from the foreground and background image pixel positions, wherein the value of the current pixel is corrected for color misregistration.

2. The method of claim 1 wherein the window is 5 pixels by 1 pixel.

3. The method of claim 1, wherein the method is performed by micro-codes in a digital signal processor.

4. The method of claim 1, wherein the gradient field is in RGB color space.

5. The method of claim 1, wherein the gradient field is in CMY color space.

6. A computer-readable medium containing a program operable to separate foreground and background image pixels, the program comprising:

code operable to detect edges in the image pixels, wherein the code compares a gradient between a current pixel and at least one neighbor pixel to a threshold;

code operable to perform gradient analysis on a selected window of pixels surrounding a current pixel, if the current pixel is an edge pixel;

code operable to classify from a classification set the gradient for the selected window of pixels, wherein the classification set comprises monotonic, similar vertex, shifted vertex, and inverted vertex;

code operable to define foreground and background pixel positions relative to the current pixel depending upon the classification of the gradient; and

code operable to interpolate a value of the current pixel from the foreground and background pixel position such that the value of the current pixel is corrected for color misregistration.

7. The computer-readable medium of claim 6, wherein the program is incorporated into image application software.

8. The computer-readable medium of claim 6, wherein the program is incorporated into a device driver.