Edge detecting method

• US 7,366,347 B2
• Filed: 03/30/2005
• Issued: 04/29/2008
• Est. Priority Date: 05/06/2004
• Status: Expired

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Magnachip Semiconductor Limited (Magnachip Semiconductor)
• Inventors: Song, Dong-Seob, Ahn, Hyun-Joo
• Primary Examiner(s): Mehta; Bhavesh M.
• Assistant Examiner(s): Seth; Manav
• Application Number:
  US11/096,637
• Publication Number:
  US 20050249417A1
• Time in Patent Office: 1,126 Days
• Field of Search: 382/162, 382/163, 382/167, 382/199, 382/254, 382260-275, 348/252, 348/538, 348/625, 345/475, 345/523, 345/606, 345/947, 358/525, 386/50, 386/73
• US Class Current: 382/162
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: H04N 2209/046 Colour interpolation to calculate the missing colour values

Abstract

There is provided an edge detecting method, which is capable of preventing a noise influence caused by imaging device and a color interpolation. The edge detecting method includes the steps of: setting a first kernel based on a center pixel in pixel data arranged in a mosaic structure; setting a second kernel based on the center pixel within the first kernel; detecting whether a pixel having a green value in the second kernel is a defective pixel, and correcting the pixel; converting all pixels of the second kernel into pixels having green value; calculating a slope value by using a mask for detecting an edge in the second kernel; and detecting an edge by adding the slope value to a luminance value obtained by a color space conversion.

Claims

1. An edge detecting method comprising the steps of:

a) setting a first kernel based on a center pixel in pixel data arranged in a mosaic structure;

b) setting a second kernel based on the center pixel within the first kernel;

c) detecting whether a pixel having a green value in the second kernel is a defective pixel, and correcting the pixel;

d) converting all pixels of the second kernel into pixels having green value;

e) calculating a slope value by using a mask for detecting an edge in the second kernel; and

f) detecting an edge by adding the slope value to a luminance value obtained by a color space conversion.

2. The edge detecting method as recited in claim 1, wherein the first kernel is a 5×

5 kernel and the second kernel is a 3×

3 kernel.

3. The edge detecting method as recited in claim 1, further comprising the step of:

prior to the step d), determining whether all pixels of the second kernel have the G value.

4. The edge detecting method as recited in claim 3, further comprising the steps of:

checking whether the pixel having the G value among the pixels of the second kernel is a defective pixel or a noise; and

correcting a luminance value of the corresponding pixel.

5. The edge detecting method as recited in claim 4, wherein the step of correcting the luminance value of the corresponding pixel includes the steps of:

setting first and second threshold values according to a luminance value of the center pixel so as to determine whether the center pixel having the G value in the second kernel is distorted or not;

calculating a difference in luminance values of the center pixel and a pixel having the same G value;

comparing the difference with the first threshold value;

if the difference is smaller than the first threshold value, increasing a count value representing the number of pixels having the same color characteristic as the center pixel;

determining whether there exists a pixel having the same color characteristic in a position adjacent to the center pixel;

if there is no pixel having the same color characteristic, determining whether a count value representing the number of adjacent pixels whose difference in the luminance value from the center pixel is larger than the first threshold value is zero; and

if the count value is zero, making an edge zero and setting a next 3×

3 kernel.

6. The edge detecting method as recited in claim 5, further comprising the steps of:

if the difference in the luminance value is larger than the first threshold value, increasing the count value representing the number of adjacent pixels whose difference in the luminance value from the center pixel is larger than the first threshold value.

7. The edge detecting method as recited in claim 5, further comprising the steps of:

if the count value representing the number of the adjacent pixels whose difference in the luminance value from the center pixel is larger than the first threshold value is not zero, determining whether the count number representing the number of the adjacent pixels larger than the first threshold value is equal to the count value representing the number of the pixel having the same color characteristic as the center pixel and whether the differences in the luminance values of the center pixel and the pixel having the same G value; and

if the condition is satisfied, multiplying a weight value by the luminance value of the center pixel according to the distortion of luminance values of pixels arranged in a previous row.

8. The edge detecting method as recited in claim 7, further comprising the step of:

if the condition is not satisfied, setting the edge to 1 and setting a next second kernel.

9. The edge detecting method as recited in claim 1, wherein the slope value is calculated using a Laplacian filter.

10. The edge detecting method as recited in claim 1, wherein a median filter or an average value is used in the step d).