Computer graphics processing and selective visual display system – Display peripheral interface input device – Light pen for fluid matrix display panel
Reexamination Certificate
1999-03-19
2001-05-22
Powell, Mark R. (Department: 2779)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Light pen for fluid matrix display panel
C345S111000, C345S182000, C707S793000
Reexamination Certificate
active
06236390
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods and apparatus for displaying images and, more particularly, to methods and apparatus for controlling the spacing and/or positioning of images such as displayed text characters.
BACKGROUND OF THE INVENTION
Color display devices have become the principal display devices of choice for most computer users. The display of color on a monitor is normally achieved by operating the display device to emit light, e.g., a combination of red, green, and blue light, which results in one or more colors being perceived by the human eye.
In cathode ray tube (CRT) display devices, the different colors of light are generated with phosphor coatings which may be applied as dots in a sequence on the screen of the CRT. A different phosphor coating is normally used to generate each of three colors, red, green, and blue. The coating results in repeated sequences of phosphor dots each of which, when excited by a beam of electrons, will generate the color red, green or blue.
The term pixel is commonly used to refer to one spot in, e.g., a rectangular grid of thousands of such spots. The spots are individually used by a computer to form an image on the display device. For a color CRT, where a single triad of red, green and blue phosphor dots cannot be addressed, the smallest possible pixel size will depend on the focus, alignment and bandwidth of the electron guns used to excite the phosphors. The light emitted from one or more triads of red, green and blue phosphor dots, in various arrangements known for CRT displays, tend to blend together giving, at a distance, the appearance of a single colored light source.
In color displays, the intensity of the light emitted from the additive primary colors, red, green, and blue, can be varied to get the appearance of almost any desired color pixel. Adding no color, i.e., emitting no light, produces a black pixel. Adding 100 percent of all three colors results in a white pixel.
Portable computing devices, including hand held devices and portable computers, often use liquid crystal displays (LCD) or other flat panel display devices
102
, as opposed to CRT displays. This is because flat panel displays tend to be smaller and lighter than CRT displays. In addition, flat panel displays are well suited for battery powered applications since they typically consume less power than comparable sized CRT displays.
Color LCD displays are examples of display devices which utilize multiple distinctly addressable elements, referred to herein as pixel sub-components or pixel sub-elements, to represent each pixel of an image being displayed. Normally, each pixel element of a color LCD display comprises three non-square elements, i.e., red, green and blue (RGB) pixel sub-components. Thus, a set of RGB pixel sub-components together define a single pixel element. Known LCD displays generally comprise a series of RGB pixel sub-components which are commonly arranged to form stripes along the display. The RGB stripes normally run the entire length of the display in one direction. The resulting RGB stripes are sometimes referred to as “RGB striping”. Common LCD monitors used for computer applications, which are wider than they are tall, tend to have RGB vertical stripes.
FIG. 1
illustrates a known LCD screen
200
comprising a plurality of rows (R
1
-R
12
) and columns (C
1
-C
16
). Each row/column intersection defines a square which represents one pixel element.
FIG. 2
illustrates the upper left hand portion of the known display
200
in greater detail.
Note in
FIG. 2
how each pixel element, e.g., the (R
1
, C
4
) pixel element, comprises three distinct sub-element or sub-components, a red sub-component
206
, a green sub-component
207
and a blue sub-component
208
. Each known pixel sub-component
206
,
207
,
208
is ⅓ or approximately ⅓ the width of a pixel while being equal, or approximately equal, in height to the height of a pixel. Thus, when combined, the three ⅓ width full height, pixel sub-components
206
,
207
,
208
form a single pixel element.
As illustrated in
FIG. 1
, one known arrangement of RGB pixel sub-components
206
,
207
,
208
form what appear to be vertical color stripes on the display
200
. Accordingly, the arrangement of ⅓ width color sub-components
206
,
207
,
208
, in the known manner illustrated in
FIGS. 1 and 2
, is sometimes called “vertical striping”.
Traditionally, each set of pixel sub-components defining a pixel element is treated as a single pixel unit. The intensity of each pixel sub-component is controlled by a luminous intensity value. Accordingly, in known systems luminous intensity values for all the pixel sub-components of a pixel element are generated from the same portion of an image. Consider for example, the image segmented by the grid
220
illustrated in FIG.
3
. In
FIG. 3
each square of the grid represents an area of an image which is to be represented by a single pixel element, e.g., a red, green and blue pixel sub-component of the corresponding square of the grid
230
. In
FIG. 3
a cross-hatched circle is used to represent a single image sample from which luminous intensity values are generated. Note how a single sample
222
of the image
220
is used in known systems to generate the luminous intensity values for each of the red, green, and blue pixel sub-components
232
,
233
,
234
. Thus, in known systems, the RGB pixel sub-components are generally used as a group to generate a single colored pixel corresponding to a single sample of the image to be represented.
Text characters are an example of images which are frequently displayed by a computer system. Spacing between characters, and the position of a character within a fixed amount of space allocated to a character, can significantly impact the perceived quality of text. In addition, character spacing is important from a document formatting perspective.
Many modern computer systems use font outline technology, e.g., scalable fonts, to support the rendering and display of text. In such systems each font, e.g., TinesNewRoman, Onyx, Courier New, etc. is supported by using a different font set. The font set normally includes a high resolution outline representation, e.g., lines points and curves, for each character which may be displayed using the font. The stored outline character representation normally does not include white space beyond the minimum and maximum horizontal and vertical boundaries of the character as to not take up extra space. Therefore, the stored character outline portion of a character font is often referred to as a black body (BB). In addition to BB information, a character font normally includes BB size, BB positioning, and overall character width information. BB size information is sometimes expressed in terms of the dimensions of a bounding box used to define the vertical and horizontal borders of the BB.
FIG. 4
illustrates a character, the letter A
400
. Box
408
is a bounding box which defines the size of the BB
407
of the character
400
. The total width of the character
400
, including optional white space to be associated with the character
400
, is specified by an advanced width (AW) value
402
. Point
404
is referred to as the left side bearing point (LSBP). The LSBP
404
marks the horizontal starting point for positioning the character
400
relative to a current display position. Point
406
is the right side bearing point (RSBP). The RSBP
406
marks the end of the current character and the point at which the LSBP
404
of the next character should be positioned. The horizontal distance located between the left side bearing point
404
and the start of the BB
407
is called the left side bearing (LSB)
410
. LSB values can be specified as either positive or negative values. The horizontal distance
412
located between the end of the BB
407
and the RSBP
406
is called the right side bearing (RSB). The RSB
412
indicates the amount of white space to be placed between the BB
407
of a current character and the LSB of
4
Havan Thu-Thao
Microsoft Corporation
Powell Mark R.
Workman & Nydegger & Seeley
LandOfFree
Methods and apparatus for positioning displayed characters does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods and apparatus for positioning displayed characters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods and apparatus for positioning displayed characters will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2547769