Computer graphics processing and selective visual display system – Computer graphics processing – Character generating
Reexamination Certificate
2000-10-06
2004-06-22
Razavi, Michael (Department: 2672)
Computer graphics processing and selective visual display system
Computer graphics processing
Character generating
C345S469100
Reexamination Certificate
active
06753862
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an outline smoothing method and system suitable for use in a character-outputting device which has bitmapped fonts, such as a printing device and a display device of a tape printing apparatus, a word processor, or a personal computer.
2. Prior Art
Conventionally, characters of various sizes have been printed or displayed by one of the following methods (1) to (3):
(1) a method of storing data of all character fonts to be printed or displayed;
(2) a method of storing and scaling (enlarging/reducing) bitmapped fonts; and
(3) a method of storing and scaling (enlarging/reducing) outline fonts.
However, the method (1) requires a huge amount of data, and hence it is not practical.
As far as the method (2) is concerned, the print quality obtained by this method is inferior to that obtained by the method (1), and the attempt to solve the problem burdens a processor with increased software-based processing, which takes much time.
More specifically, to improve print quality, a printing device using a bitmap font carries out smoothing of “stairsteps” of the outline of an enlarged character image. A “stairstep” here means a portion of the outline of a character image, which appears stepped due to lack of bit map data for a diagonally adjacent portion between diagonally arranged dots, and develops a break or corrupted portion with enlargement of the character image.
For smooth outlines of character images, it has been conventionally carried out to detect such “stairsteps”, and when the character images are enlarged, correction dots are added to infill the “stairsteps”.
However, in the smoothing processing, if correction dots are increased in number, the contour of a character looses its shape to spoil the design of the character, whereas if the number of correction dots is reduced, jaggies remain noticeable on the outline of the character, so that as the scaling factor is larger, the correction of the image becomes less effective.
The method (3) requires a larger system size and a larger amount of data than the method (2), so that in a printing apparatus of a relatively small size, such as a tape printing apparatus, this method can be employed at the cost of either an increased processing time or an increased market price.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an outline smoothing method, system and storage medium that enables a character image of a bitmapped font having an outline which looks smooth even when the character image is enlarged by a large scaling factor.
To attain the above object, according to a first aspect of the present invention, there is provided a method of smoothing an outline of a character image of a bitmapped font defined by bitmap data in a dot matrix format, the method comprising the steps of:
converting the bitmap data temporarily to vector data when the character image is expanded;
drawing lines on a new bitmap based on a sequence of a predetermined number of vectors, the sequence being shifted, one vector by one vector, from a start of the vector data to an end of the vector data, to thereby form an outline of the enlarged character image; and
filling an inside of the outline with dots to thereby produce new bitmap data representative of the enlarged character image.
Preferably, the step of drawing lines includes the steps of:
determining basic outline coordinate points, based on the vector data;
correcting the basic outline coordinate points with reference to correction data defined in advance in a manner corresponding to respective patterns of variation in the sequence of the predetermined number of vectors, to thereby form corrected outline coordinate points; and
connecting between each pair of adjacent ones of the corrected outline coordinate points by a line.
To attain the above object, according to a second aspect of the invention, there is provided a method of smoothing an outline of a character image of a bitmapped font defined by bitmap data in a dot matrix format, the method comprising the steps of:
determining coordinates of a starting point of the bitmap data, according to predetermined conditions, the starting point being associated with a start of vector data into which the bitmap data is converted, while referring to vectorized dot information indicative of whether or not each dot of the bitmap data has been vectorized;
converting the bitmap data to an orthogonal vector sequence by sequentially determining a direction of each adjacent dot of the bitmap data which is located next to a corresponding preceding dot, starting from the starting point, according to a predetermined order, and converting the each adjacent dot of the bitmap data into a vector of a direction of any of upward, downward, leftward, and rightward directions, with reference to the determined direction, while at the same time updating the vectorized dot information;
converting the orthogonal vector sequence to a diagonal vector sequence based on each sequence of a predetermined number of vectors of the orthogonal vector sequence, with reference to a diagonalization table defining in advance predetermined patterns of the each of sequence which is to be applied for converting a vector of the diagonal vector sequence to a diagonal vector;
carrying out line-drawing processing by producing bitmap coordinate points based on the starting point and the diagonal vector sequence and correcting the bit map coordinate points with reference to a correction data table defining in advance amounts of correction in units of dots in a manner associated with respective patterns of each sequence of a predetermined number of vectors of the diagonal vector sequence;
causing aforementioned steps to be repeatedly carried out until the step of determining the coordinates of a starting point can determine no more starting point, to thereby produce line data representative of results of the line-drawing processing; and
producing new bitmap data based on the line data.
Preferably, the step of carrying out line-drawing processing includes producing data defining an outline of the character image and data defining a line for filling an inside thereof with dots by filling processing, and the step of producing new bit map data comprises the steps of:
carrying out the filling processing;
superposing data obtained by the filling processing and the data defining the outline one upon another; and
carrying out stroke width-reducing processing for reducing a stroke width of the character image increased due to the vectorization.
Preferably, the step of determining coordinates of the starting point includes scanning dots of the bitmap data sequentially in a predetermined direction, and determining, as the coordinates of the starting point, coordinates of a dot which is not indicated to be vectorized by the vectorized dot information, and at the same time, shows a change from its immediately preceding dot.
Preferably, the step of converting the bitmap data to an orthogonal vector sequence comprises the steps of:
setting a vector value corresponding to the starting point and updating the vectorized dot information such that the starting point is vectorized;
shifting a dot position for vectorization to a next dot in a vector direction;
checking dots around the next dot to thereby determine a vector value of the next dot;
updating the vectorized information such that a dot corresponding to the shifted dot position is vectorized if the dot corresponding to the shifted dot position can be a candidate for the starting point; and
repeatedly executing the aforementioned step of shifting the dot position to the aforementioned step of updating the vectorized dot information until the dot position for vectorization returns to the starting point.
Preferably, the step of carrying out line-drawing processing includes the steps of:
determining a starting coordinate point of a basic outline before correction, based on the starting point, according to predetermined conditions, and then determining each following coordinate p
Miyasaka Noriaki
Omoto Ryuji
Yanagisawa Shigekazu
Hogan & Hartson LLP
Razavi Michael
Yang Ryan
LandOfFree
Outline smoothing method and system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Outline smoothing method and system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Outline smoothing method and system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3357135