Converting bitmap objects to polygons

A computer program tangibly stored on a computer-readable medium for converting a bitmap object to a polygon, the bitmap object having a boundary defining the perimeter of the bitmap object where the boundary includes one or more boundary pixels having one or more edge line segments shared with non-object pixels that contribute to the perimeter, the program comprising:

• a tracing module including instructions for causing a computer to trace around the boundary of the bitmap object and generate a plurality of chain direction codes where each chain direction code defines a direction from a boundary pixel to an adjacent boundary pixel;
• a polygon generating module including instructions for causing the computer to identify for each boundary pixel one or more edge line segments shared with non-object pixels that contribute to the perimeter based on two or more of the chain direction codes generated by the tracing module and to produce as output a polygon having an outline defined by the edge line segments;
• and
• a vector-based trapping module including instructions for causing the computer to define traps for the polygon.

A computer-implemented method of trapping a bitmap object, comprising:

• identifying boundary pixels of the bitmap object, a boundary pixel being an object pixel that shares an edge with a non-object pixel or a non-object pixel that shares an edge with an object pixel;
• for each identified boundary pixel, identifying all of the perimeter edge line segments of the bitmap object, a perimeter edge line segment being a line segment that separates adjacent pixels and contributes to the perimeter of the bitmap object;
• accumulating the identified perimeter edge line segments to define a polygon;
• and
• defining traps for the polygon.

A method for printing a page including a bitmap object, comprising:

• defining the bitmap object as a polygon, including identifying boundary pixels of the bitmap object, a boundary pixel being an object pixel that shares an edge with a non-object pixel or a non-object pixel that shares an edge with an object pixel, and for each identified boundary pixel identifying all of the perimeter edge line segments of the bitmap object and accumulating the identified perimeter edge line segments to define the polygon, a perimeter edge line segment being a line segment separating the adjacent pixels and contributing to the perimeter of the bitmap object;
• mapping the polygon to device space;
• filling the polygon;
• and
• rendering the page using the filled polygon.

A computer program product for printing a page including a bitmap object, the product comprising instructions operable to cause an instruction processor to:

• receive a bitmap object;
• define the bitmap object as a polygon by identifying boundary pixels of the bitmap object, a boundary pixel being an object pixel that shares an edge with a non-object pixel or a non-object pixel that shares an edge with an object pixel, and for each identified boundary pixel identifying all of the perimeter edge line segments of the bitmap object and accumulating the identified perimeter edge line segments to define the polygon, a perimeter edge line segment being a line segment separating adjacent pixels and contributing to the perimeter of the bitmap object;
• map the polygon to device space;
• fill the polygon;
• and
• render the page using the filled polygon.

A computer program product for generating a polygon from a bitmap object defined by object pixels, each of the object pixels having edges shared with adjacent pixels, the product comprising instructions operable to cause an instruction processor to:

• identifying boundary pixels of the bitmap object, a boundary pixel being an object pixel that shares an edge with a non-object pixel or a non-object pixel that shares an edge with an object pixel;
• for each identified boundary pixel, identify all of the perimeter edge line segments, a perimeter edge line segment being an edge line segment that separates an object pixel from a non-object pixel;
• accumulate the identified perimeter edge line segments to define a polygon;
• and
• use the polygon to define traps for the object.