Shape descriptor extracting method

A shape descriptor extracting method comprising:

• (a) extracting a skeleton from an input image;
• (b) obtaining a first list of straight lines by connecting pixels based on the extracted skeleton;
• and
• (c) determining a second list of straight lines obtained by normalizing the first list of straight lines as a shape descriptor,
• wherein the step (a) comprises:
• (a-1) obtaining a distance map by performing a distance transform on the input image;
• and
• (a-2) extracting the skeleton from the obtained distance map,
• the step (a-2) comprises:
• obtaining a local maximum from the distance map using an edge detecting method, and
• the step (a-2) comprises:
• (a-2-1) performing a convolution using a local maximum detecting mask of four directions to obtain the local maximum.

A shape descriptor extracting method comprising:

• (a) extracting a skeleton from an input image;
• (b) obtaining a first list of straight lines by connecting pixels based on the extracted skeleton;
• and
• (c) determining a second list of straight lines obtained by normalizing the first list of straight lines as a shape descriptor,
• wherein the step (b) further comprises:
• (b-1) thinning the extracted skeleton;
• and
• (b-2) extracting the first list of straight lines by connecting respective pixels within the thinned skeleton, and
• the step (b-1) comprises:
• leaving a pixel having the greatest size in a direction rotated by 90-degrees from the corresponding direction on the direction map, and removing the rest of the pixels.

A shape descriptor extracting method comprising:

• (a) extracting a skeleton from an input image;
• (b) obtaining a first list of straight lines by connecting pixels based on the extracted skeleton;
• and
• (c) determining a second list of straight lines obtained by normalizing the first list of straight lines as a shape descriptor,
• wherein the step (b) comprises:
• (b-1) thinning the extracted skeleton;
• and
• (b-2) extracting the first list of straight lines by connecting respective pixels within the thinned skeleton, and
• the step (b-2) comprises:
• using the direction map of four directions, and making a list of starting points and ending points of respective line segments by connecting pixels having the same level on the direction map.

A shape descriptor extracting method comprising:

• (a) extracting a skeleton from an input image;
• (b) obtaining a first list of straight lines by connecting pixels based on the extracted skeleton;
• and
• (c) determining a second list of straight lines obtained by normalizing the first list of straight lines as a shape descriptor,
• wherein (b) comprises connecting pixels having a same level on direction maps of a plurality of directions to obtain the first list of straight lines wherein (b) comprises using the direction map of four directions, and making a list of starting points and ending points of respective line segments by connecting pixels having the same level on the direction map.

A shape descriptor extracting method comprising:

• (a) extracting a skeleton from an input image;
• (b) obtaining a first list of straight lines by connecting pixels based on the extracted skeleton;
• and
• (c) determining a second list of straight lines obtained by normalizing the first list of straight lines as a shape descriptor,
• wherein (b) comprises connecting pixels having a same level on direction maps of a plurality of directions to obtain the first list of straight lines, wherein the direction maps of the plurality of directions comprise masks of the plurality of directions.