Computer graphics processing and selective visual display system – Display peripheral interface input device – Light pen for fluid matrix display panel
Reexamination Certificate
1999-06-16
2001-07-17
Brier, Jeffery (Department: 2672)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Light pen for fluid matrix display panel
C345S440000, C348S468000, C348S581000
Reexamination Certificate
active
06262708
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates generally to display systems. More particularly, methods and apparatus for displaying complex characters on a monitor are disclosed.
2. Description of Relevant Art
Displaying the contents of WEB pages on standard television monitors has always been a challenging problem due in part to the fact that standard television monitors have a much lower resolution as compared to standard computer monitors. By way of example,
FIG. 1
illustrates a conventional NTSC standard TV picture
100
. The TV picture
100
is formed of an active picture area
102
that is the area of the TV picture
100
that carries picture information. Outside of the active picture area
102
is a blanking region
104
suitable for line and field blanking. The active picture area
102
uses frames
106
, pixels
108
and scan lines
110
to form the actual TV image. The frame
106
represents a still image produced from any of a variety of sources such as an analog video camera, an analog television, etc. In systems where interlaced scan is used, each frame
106
represents a field of information. Frame
106
may also represent other breakdowns of a still image depending upon the type of scanning being used. Information in frame
106
is represented by any number of pixels
108
. A pixel ( an acronym for “picture element”) is the smallest distinguishable and resolvable area in an image as well as the discrete location of an individual photo-sensor in a solid state camera. Each pixel in turn represents digitized information and is often represented by 8 bits, although each pixel may be represented by any number of bits. Each scan line
110
includes any number of pixels
108
, thereby representing a horizontal line of information within frame
106
.
In NTSC video (a television standard using interlaced scan), for example, a field of information appears every 60th of a second, a frame (including 2 fields) appears every 30th of a second and the continuous presentation of frames of information produce a picture. An interlaced display is a display in which the lines are scanned alternately in two interwoven rasters. In a conventional interlaced display, there are several hundred horizontal lines in a frame (full screen). These lines are scanned from left to right, and from top to bottom. The refresh rate (number of frames scanned per second) varies, but it is normally between 60 and 100 Hz. Refresh rates slower than 60 Hz produce distracting screen flicker, which can cause headaches and eye fatigue. Since a computer monitor using progressive scan refreshes the frame of information on the screen every 30th of a second with no interlacing of frames, the problem of flicker is substantially eliminated in computer monitors using progressive scan techniques.
It is in part due to the combination of low resolution and the presence of image flicker that presents a substantial challenge to displaying WEB pages, digital images, text, and the like on standard NTSC format monitors. In order to display an image, such as an alphanumeric character on a television monitor, the character image is typically converted to what is referred to as a graphics bitmap suitable for storage in a memory device coupled to the television. Such memory devices are typically included in set top boxes used in conjunction with cable modems, WEBTV™ terminals, and the like.
A conventional approach to displaying the alphanumeric character includes preprocessing the character bitmap to reduce the flicker using various anti-aliasing techniques well known to those skilled in the art. Anti-aliasing is a technique used on a gray-scale or color bitmap displays to make diagonal edges appear smoother by setting pixels near the edge to intermediate colors according to where the edge crosses them. Typically, applying conventional anti-aliasing techniques to character bitmaps to reduce flicker has the effect of blurring the character image. In the case of simply connected characters such as, for example, those characters found in the Roman alphabet, this blurring presents no real problem since the characters remain substantially legible. However, for complex characters that are formed of many strokes, such as those found in the Chinese and Korean language, this blurring renders these multiply connected characters substantially illegible, or in some cases, changes the entire meaning of the character.
Therefore, what is desired are techniques for legibly displaying complex characters typical of, for example, the Chinese and Korean language, on a standard television monitor.
SUMMARY OF THE INVENTION
Broadly speaking, the invention relates to an improved method, apparatus and system for displaying complex characters on a standard television monitor. The invention can be implemented in numerous ways, including as a method, a system, an apparatus, and a computer readable medium. Several embodiments of the invention are discussed below.
According to one aspect of the present invention, a method of rendering an image of a complex character for display on a standard television monitor is described. As a method, a raw character bitmap representing the complex character is filtered and contrast enhanced to form a filtered character bitmap. The filtered character bitmap is then scaled down using multiple type scaling operations to a target character bitmap suitable for storage in a memory coupled to the television. In one embodiment, the filtered character bitmap is initially scaled using a bilinear scaling technique followed by recursive cubic scaling techniques until the filtered character bitmap is reduced in size to that of the target character bitmap.
According to another aspect of the present invention, an apparatus for rendering an image of a complex character for display on a standard television monitor is described. The apparatus includes a filter unit arranged to filter and contrast enhance a raw character bitmap representing the complex character to form a filtered character bitmap. A decimator unit coupled to the filter unit uses multiple type scaling techniques to reduce the size of the filtered character bitmap to that of a target character bitmap suitable for storing in a memory device coupled to the monitor.
In one embodiment, the multiple type scaling techniques include a first bilinear scaling operation followed by recursive cubic scaling operations.
These and other advantages of the present invention will become apparent upon reading the following detailed descriptions and studying the various figures of the drawings.
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Beyer Weaver & Thomas LLP.
Brier Jeffery
Havan Thu-Thao
Sun Microsystems Inc.
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