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Character Generation – Bitmap Font and Bit Mapped Font | Freestudy9

Character Generation

Character Generation is the important topic of the Computer Graphics. Moreover, It is the Important subject of the Computer Science & Technological field.

Character Generation

We can display letters and numbers in a variety of size and style.

The overall design style for the set of character is called typeface.

Today large numbers of typefaces are available for a computer application, for example, Helvetica, New York platino etc.

Originally, the term font referred to a set of cast metal character forms in a particular size and format, such as 10-point Courier Italic or 12- point Palatino Bold. Now, the terms font and typeface are often used interchangeably, since printing is no longer done with cast metal forms.

Two different representations are used for storing computer fonts.

Bitmap Font/ Bitmapped Font: Character Generation

  • A simple method for representing the character shapes in a particular typeface is to use rectangular grid patterns.
  • The figure below shows the pattern for the particular letter.


  • When the pattern in the figure copied to the area of the frame buffer, the 1 bits designate which pixel positions to displayed on the monitor.
  • Bitmap fonts the simplest to define and display as character grid only need to be mapped to a framebuffer position.
  • Bitmap fonts require more space because each variation (size and format) must stored in a font cache.
  • It possible to generate different size and other variation from one set but this usually does not produce the good result.

Outline Font: Character Generation


  • In this Character Generation method, a character generated using curve section and straight line as combine assembly. The figure shows how it generated.
  • To display the character shown in the figure we need to fill interior region of the character.
  • This method requires less storage since each variation does not require a distinct font cache.
  • We can produce boldface, italic, or different sizes by manipulating the curve definitions for the character outlines.
  • But this will take more time to process the outline fonts because they must scan converted into the frame buffer.

Stroke Method: Character Generation

  • It uses small line segments to generate a character.
  • The small series of line segments drawn like a stroke of a pen to form a character as shown in the figure.
  • We can generate our own stroke method by calling line drawing algorithm.
  • Here it is necessary to decide which line segments are needs for each character and then draw that line to display character.
  • It supports scaling by changing a length of the line segment.

Starburst Method: Character Generation


In this Character Generation method, a fixed pattern of line segments used to generate characters.

As shown in the figure there are 24 line segments.

We highlight those lines which are necessary to draw a particular character.

The pattern for the particular character stored in the form of 24-bit code. In which each bit represents the corresponding line having that number.

That code contains 0 or 1 based online segment need to highlight. We put bit value 1 for highlighted line and 0 for other lines.

Code for letter V is

  • 1 0 0 1 1 1 0 0 0 0 1 0 0 1 1 0 0 0 0 0 0 0 0

This technique not used now a days because:

  • It requires more memory to store 24 bit code for single character.
  • Moreover, It requires conversion from code to character.

It doesn’t provide curve shapes.


Related Terms

Computer Graphics, Flood-Fill Algorithm, Filled-Area Primitives, Inside-Outside Tests, Curved Boundary Areas

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