Character Generator Methods:
1) Stroke Method
2) Bitmap Method
3) Starburst Method
1) STROKE METHOD
Stroke method is based on natural method of text written by human being. In this method graph is drawing in the form of line by line. Line drawing algorithm DDA follows this method for line drawing. This method uses small line segments to generate a character. The small series of line segments are drawn like a stroke of pen to form a character. We can build our own stroke method character generator by calls to the line drawing algorithm. Here it is necessary to decide which line segments are needed for each character and then drawing these segments using line drawing algorithm.
2)BITMAP METHOD Bitmap method is a called dot-matrix method as the name suggests this method use array of bits for generating a character. These dots are the points for array whose size is fixed. In bit matrix method when the dots is stored in the form of array the value 1 in array represent the characters i.e. where the dots appear we represent that position with numerical value 1 and the value where dots are not present is represented by 0 in array. It is also called dot matrix because in this method characters are represented by an array of dots in the matrix form. It is a two dimensional array having columns and rows. A 5x7 array is commonly used to represent characters. However 7x9 and 9x13 arrays are also used. Higher resolution devices such as inkjet printer or laser printer may use character arrays that are over 100x100.
3) Starbust method: In this method a fix pattern of line segments are used to generate characters. Out of these 24 line segments, segments required to display for particular character are highlighted. This method of character generation is called starbust method because of its characteristic appearance
The starbust patterns for characters A and M. the patterns for particular characters are stored in the form of 24 bit code, each bit representing one line segment. The bit is set to one to highlight the line segment; otherwise it is set to zero. For example, 24-bit code for Character A is 0011 0000 0011 1100 1110 0001 and for character M is 0000 0011 0000 1100 1111 0011.
This method of character generation has some disadvantages. They are
1. The 24-bits are required to represent a character. Hence more memory is
required.
2. Requires code conversion software to display character from its 24-bit code.
3. Character quality is poor. It is worst for curve shaped characters.
Character A : 0011 0000 0011 1100 1110 0001
Character M:0000 0011 0000 1100 1111 0011