Outlining method for properly representing curved line and straight line, and image compression method using the same

An outlining apparatus comprising:

• an extraction unit configured to extract contour pixels from binarized image data;
• and
• an approximation unit configured to perform straight-line approximation for a contour of said image data based on said extracted contour pixels,
• said approximation unit including
• a calculation unit configured to calculate a distance between adjacent contour pixels among said extracted contour pixels;
• and
• a determination unit configure to determine based on a result of a comparison between a length of a first straight line connecting a first contour pixel and a second contour pixel adjacent to said first contour pixel and a length of a second straight line connecting said second contour pixel and a third contour pixel adjacent to said second contour pixel whether said first straight line is used as a contour of said image data.

A computer readable medium storing a computer executable program for outlining, the program comprising program code for causing a computer to execute the steps of:

• extracting contour pixels from binarized image data;
• and
• performing straight-line approximation for a contour of said image data based on said extracted contour pixels,
• said step of performing straight-line approximation including the steps of
• calculating a distance between adjacent contour pixels among said extracted contour pixels, and
• determining based on a result of a comparison between a length of a first straight line connecting a first contour pixel and a second contour pixel adjacent to said first contour pixel and a length of a second straight line connecting said second contour pixel and a third contour pixel adjacent to said second contour pixel whether said first straight line is used as a contour of said image data.