Method and apparatus for detecting objects in an image

• US 8,433,133 B2
• Filed: 12/12/2011
• Issued: 04/30/2013
• Est. Priority Date: 01/12/2007
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Guerzhoy, Michael, Zhou, Hui
• Primary Examiner(s): Desire, Gregory M
• Application Number:
  US13/323,395
• Publication Number:
  US 20120087579A1
• Time in Patent Office: 505 Days
• Field of Search: 382/164, 382/165, 382/170, 382/181
• US Class Current: 382/164
• CPC Class Codes: G06T 2207/10008 from scanner, fax or copier
• CPC Class Codes: G06T 2207/30176 Document
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/143 involving probabilistic approaches, e.g. Markov random field [MRF] modelling
• CPC Class Codes: G06T 7/181 involving edge growing; involving edge linking

Abstract

A method of detecting generally rectangular objects in an image comprises determining candidate rectangles in the image based on detected corners in the image, ranking the candidate rectangles on the basis of a set of differentiating factors and detecting objects in the images based on the ranked candidate rectangles.

Claims

1. A method of estimating background color in an image comprising:

providing a computing device to implement to following steps;

accessing said image, wherein said image is comprised of a plurality of rows of pixels, each pixel having a color defined by a color vector comprised of multiple color values, each row of pixels within the image defining a scan line of the image;

segmenting each scan line of the image into like-color line segments, wherein the colors of the pixels within each respective like-color line segment have a normal distribution about a mean color of the respective like-color line segment, and the standard deviation of the colors within each like-color line segment is smaller than a difference between its mean color and the mean color of its adjacent like-color line segment;

grouping the like-color line segments by color; and

estimating the background color on the basis of edge pixels along the line segments of said groups.

2. The method of claim 1 wherein during said grouping, only like-color line segments exceeding a threshold length are grouped.

3. The method of claim 2 wherein said estimating is made on the basis of the number and strength of edge pixels.

4. The method of claim 1, wherein said color vector is comprised of Red, Green, Blue (RGB) color values.

5. The method of claim 1, wherein said estimating is made on the basis of only edge pixels.

8. The apparatus of claim 5, wherein during said grouping, only like-color line segments exceeding a threshold length are grouped.

9. The apparatus of claim 8, wherein said estimating is made on the basis of the number and strength of edge pixels.

10. The apparatus of claim 9, wherein said estimating comprises:

determining the groups of like-color line segments having a threshold number of line segments;

designating the average color of each group of like-color line segments as a candidate background color;

for each candidate background color, detecting edge pixels along the line segments of the group representing that candidate background color and calculating the strength of edges defined by the edge pixels; and

selecting one of the candidate background colors as the background color estimate based on edge pixel count and edge strength.

11. The apparatus of claim 5, wherein said color vector is comprised of Red, Green, Blue (RGB) color values.

12. The method of claim 5, wherein said estimating is made on the basis of only edge pixels.

6. A method of estimating background color in an image comprising:

providing a computing device to implement the following steps;

segmenting each scan line of the image into like-color line segments;

grouping the like-color line segments by color; and

estimating the background color on the basis of edge pixels along the line segments of said groups;

wherein said estimating comprises;

determining the groups of like-color line segments having a threshold number of line segments;

designating the average color of each group of like-color line segments as a candidate background color;

for each candidate background color, detecting edge pixels along the line segments of the group representing that candidate background color and calculating the strength of edges defined by the edge pixels; and

selecting one of the candidate background colors as the background color estimate based on edge pixel count and edge strength.

7. An apparatus for estimating background color in an image comprising:

memory for storing said image, wherein said image is comprised of a plurality of rows of pixels, each pixel having a color defined by a color vector comprised of multiple color values, each row of pixels within the image defining a scan line of the image; and

processing structure communicating with the memory, said processing structure;

processing the image to segment each scan line of the image into like-color line segments, wherein the colors of the pixels within each respective like-color line segment have a normal distribution about a mean color of the respective like-color line segment, and the standard deviation of the colors within each like-color line segment is smaller than a difference between its mean color and the mean color of its adjacent like-color line segment;

grouping the like-color line segments by color; and

estimating the background color on the basis of edge pixels along the line segments of the groups.

13. An apparatus for estimating background color in an image comprising:

a memory for storing said image; and

a processing structure communicating with the memory, said processing structure processing the image to segment each scan line of the image into like-color line segments, grouping the like-color line segments by color and estimating the background color on the basis of edge pixels along the line segments of the groups;

wherein said estimating the background color comprises;

determining the groups of like-color line segments having a threshold number of line segments;

designating the average color of each group of like-color line segments as a candidate background color;

for each candidate background color, detecting edge pixels along the line segments of the group representing that candidate background color and calculating the strength of edges defined by the edge pixels; and

selecting one of the candidate background colors as the background color estimate based on edge pixel count and edge strength.