Automatic cutting method for digital images

• US 20050254728A1
• Filed: 05/13/2004
• Published: 11/17/2005
• Est. Priority Date: 05/13/2004
• Status: Abandoned Application

• Current Assignee: Primax Electronics Limited
• Original Assignee: Primax Electronics Limited
• Inventors: Wang, Zhuo-Ya
• Application Number:
  US10/844,503
• Publication Number:
  US 20050254728A1
• Time in Patent Office: Days
• US Class Current: 382/291
• CPC Class Codes: H04N 1/38 Circuits or arrangements for blanking or otherwise eliminating unwanted parts of pictures H04N1/387 takes precedence

Abstract

An automatic cutting method for digital images first extracts the brightness of a pixel in an image. The brightness is used to determine a quasi-image pixel. Actual image pixels are then extracted from the quasi-image pixels. The image boundary is then determined according to the image pixels. Finally, the image is cut according to the boundary.

Claims

1. An automatic digital image cutting method for determining a boundary of an image and automatically cutting the image, the method comprising the steps of:

extracting the brightness values of pixels in the image;

determining quasi-image pixels according to the brightness values;

extracting image pixels from the quasi-image pixels;

determining the image boundary according to the image pixels; and

cutting the image according to the boundary.

2. The method of claim 1, wherein the step of determining quasi-image pixels according to the brightness values is performed by removing background pixels in the image according to the brightness values.

3. The method of claim 1, wherein the step of extracting image pixels from the quasi-image pixels is performed by removing speckle pixels from the quasi-image pixels.

4. The method of claim 1, wherein the step of determining the image boundary according to the image pixels includes the steps of:

extracting the edge pixels of the image; and

determining the image boundary according to the edge pixels.

5. The method of claim 1, wherein the step of determining the image boundary according to the image pixels includes:

marking the edge pixels of the image as the boundary;

scanning the image by rows, marking an encountered image pixel, and updating the row of the marked image pixel as the new boundary;

marking the current pixel and comparing it with the position of the current boundary; and

updating the column of the current image pixel outside the boundary as the new boundary.

6. The method of claim 5 further comprising the step of marking the first pixel as the upper boundary and the last pixel as the lower boundary.

7. The method of claim 1, wherein the step of determining the image boundary according to the image pixels includes the steps of:

scanning the image by rows and marking the row of the first image pixel as the upper boundary and the row of the last image pixel as the lower boundary; and

scanning the image by columns and marking the column of the first pixel as the left boundary and the column of the last pixel as the right boundary.

8. The method of claim 1, wherein the step of determing the image boundary according to the image pixels includes the steps of:

scanning the image by rows from the top and from left to right, marking the first encountered image pixel as an upper left pixel;

scanning the image by rows from the bottom and from right to left, marking the first encountered image pixel as a lower right pixel; and

determining the image boundary according to the upper left pixel and the lower right pixel.

9. The method of claim 3, wherein the step of determining the speckle pixels includes the steps of:

computing the difference between the current pixel and each of its adjacent pixels;

marking the adjacent pixel as a special pixel when the difference is greater than a second base value;

counting the number of the special pixels surrounding the current pixel;

marking the current pixel as a speckle pixel when the number of special pixels is greater than a third base value.

10. The method of claim 3, wherein the step of determining the speckle pixels includes the steps of:

computing the average value of the current pixel and all its adjacent pixels;

computing the difference between the current pixel and the average value; and

marking the current pixel as a speckle pixel when the difference is greater than a fourth base value.