Vector method for color misregistration detection in image data

• US 6,556,313 B1
• Filed: 09/27/1999
• Issued: 04/29/2003
• Est. Priority Date: 09/27/1999
• 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: Otsu, Makoto, Chang, William Ho
• Primary Examiner(s): Chang, Jon
• Assistant Examiner(s): LAROSE, COLIN M
• Application Number:
  US09/405,966
• Time in Patent Office: 1,310 Days
• Field of Search: 382/162-167, 358/520, 358/521, 358/518, 358/461, 358/505, 358/512, 358/1.9, 358/3.26, 358/530, 358/540, 345/611
• US Class Current: 358/1.9
• 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 color misregistration detection. Input image data is buffered and transferred to vector space. An examination window for a current pixel is established and foreground and background pixels within that window are selected. The current pixel is examined to determine if it is in an edge of a scanned object. If the current pixel is in an edge, it is analyzed for color misregistration. The analysis includes an application of Stokes'"'"' theorem. If the results of the application of Stokes'"'"' theorem indicate that the color misregistration is above a threshold, the pixel is identified as having color misregistration.

Claims

1. A method for detecting color misregistration of input images, comprising the steps of:

a) buffering image data received from an image capture device in the form of color space data;

b) transferring said color space data to vector space;

c) establishing a window around and including a current pixel;

d) selecting foreground and background pixels in said window;

e) determining if said current pixel is in an edge of an object; and

f) analyzing said pixel by integrating across several pixels in said window to determine if the magnitude of color misregistration exceeds a threshold, if said pixel is in an edge of an object.

2. The method as claimed in claim 1 wherein said method further includes a step of initially determining if a pixel is on an edge, said step occurring between said establishing step and said selecting steps.

3. The method as claimed in claim 1 wherein said establishing step further comprises establishing a window of 5 pixels in the sub-scan direction and 1 pixel in the main scan direction.

4. The method as claimed in claim 1, wherein said determining step further comprises a gradient check and a luminance check on said current pixel.

5. The method as claimed in claim 1, wherein said analyzing step further comprises applying Stokes'"'"' theorem to said vector space.

6. The method as claimed in claim 1, wherein said color space is RGB.

7. The method as claimed in claim 1, wherein said color space is CMY.

8. The method as claimed in claim 1, wherein said color space is CMYK.

9. The method as claimed in claim 1, wherein said color space is a luminance and chrominance color space.