Computer graphics processing and selective visual display system – Computer graphics processing – Attributes
Reexamination Certificate
2000-01-19
2002-10-15
Razavi, Michael (Department: 2672)
Computer graphics processing and selective visual display system
Computer graphics processing
Attributes
C345S594000
Reexamination Certificate
active
06466224
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an image data composition apparatus for laying an image including a transparent color over a background image.
BACKGROUND OF THE INVENTION
In recent years, with the development of high-performance car navigation systems and satellite broadcast receivers, image display units employed in these devices perform composition of image data using transparent colors, such as composition of semi-transparent non-rectangular objects or screen display of transparent color menu.
FIG. 12
is a functional block diagram illustrating a conventional image display apparatus for composing a transparent color image with a background image. The image display apparatus comprises an image data composition unit
110
, a first image memory
20
, a second image memory
30
, a digital-to-analog converter
40
, a monitor
50
, and a controller
180
.
The first image memory
20
stores image data
100
to be laid over a background image. The image data
100
possesses a color code which indicates information relating to the color of each pixel, and it is supplied from an external CPU (Central Processing Unit) or the like through a bus. The second image memory
30
stores image data
200
as a background. The image data
200
possesses RGB type color data which indicates information relating to the color of each pixel, and it is supplied from an external CPU or the like through a bus. The controller
180
controls pixel-by-pixel output of the color data or the color code from these image data to the image data composition unit
110
. The digital-to-analog converter (DAC)
40
converts digital data output from the image data composition unit
110
to an analog image signal. The monitor
50
displays an image on the basis of this image signal.
The image data composition unit
110
comprises a color table
111
, a transparency register
112
, a transparency decision unit
115
, a selector
113
, and a compositor
114
. The color table
111
contains color data corresponding to plural color codes, and outputs a color data signal d
1
in response to a color code signal c
1
obtained from the first image memory
20
. The transparency register
112
stores one transparency &agr;
0
.
The transparency decision unit
115
stores the color code of a color to be a transparent color, and outputs a hit signal s only when the color code c
1
output from the first image memory
20
is equal to the stored color code. On receipt of the hit signal s, the selector
113
selects the transparency &agr;
0
stored in the transparency register
112
and outputs it as a transparency signal &agr;. When there is no hit signal s, the selector
113
outputs “0” as a transparency signal &agr;. Here, “0” means that the transparency is 0, i.e., an opaque color.
FIG. 13
is a block diagram illustrating the transparency decision unit
115
and the selector
113
in more detail. As shown in
FIG. 13
, the transparency decision unit
115
comprises transparent color registers
1151
a
and
1151
b
and comparators
1152
a
and
1152
b
. The transparent color registers
1151
a
and
1151
b
store the color codes of colors to be transparent colors. The comparators
1152
a
and
1152
b
are connected to the color registers
1151
a
and
1151
b
, respectively. Each of these comparators outputs a hit signal s only when the color code c
1
output from the first image memory
20
is equal to the color code stored in the transparent color register
1151
a
or
1151
b
. The selector
113
comprises a tri-state gate
1131
a
and a tri-state gate
1131
b
. The tri-state gate
1131
a
outputs the transparency &agr;
0
stored in the transparency register
112
on receipt of the hit signal s, and the tri-state gate
1131
b
outputs “0” when there is no hit signal s.
The compositor
114
composites a color data signal d
2
which is obtained from the second image data
200
with a color data signal d
1
which corresponds to the first image data
100
and is obtained from the color table
111
in accordance with the color code signal c
1
, pixel by pixel, on the basis of the transparency signal &agr;, and outputs composite image data dm as the result of composition.
Hereinafter, the operation of the image data composition apparatus so constructed will be described. Initially, the color data stored in the second image memory
30
is read by raster scan under control of the controller
180
to be output to the compositor
114
as a color data signal d
2
. Likewise, the color code signal c
1
is output from the first image memory
20
by raster scan, and converted to a color data signal d
1
by the color table
111
to be output to the compositor
114
.
On the other hand, the color code signal c
1
read from the first image memory
20
is also input to the transparency decision unit
115
. In the transparency decision unit
115
, the color code represented by the color code signal c
1
is compared with the color codes stored in the transparent color registers
1151
a
and
1151
b
by the comparators
1152
a
and
1152
b
, respectively. When it is equal to any of these color codes stored, a hit signal s is output to the selector
113
, and when it is equal to none of these color codes, no hit signal is output. When the selector
113
receives the hit signal s, the tri-state gate
1131
a
outputs the transparency &agr;
0
which is set in the transparency register
112
, as a transparency signal &agr;, to the compositor
114
. When no hit signal is input to the selector
113
, the tri-state gate
1131
b
outputs “0” as a transparency signal a to the compositor
114
. The compositor
114
composes the color data d
1
of the first image data and the color data d
2
of the second image data, pixel by pixel, in accordance with the transparency signal &agr;, and outputs composite data. The composite data is converted to an analog image signal by the digital-to-analog converter
40
, and the analog image signal is sent to the monitor
50
to be displayed as an image.
In the conventional image data composition unit
110
constructed as described above, the transparency decision unit
115
needs transparent color registers and comparators as many as the number of colors to be set as transparent colors. For example, in the conventional composition unit
110
, since the transparency decision unit
115
has two transparent color registers
1151
a
and
1151
b
and two comparators
1152
a
and
1152
b
, two transparent colors can be set. However, when ten transparent colors are desired to be set, ten transparent color registers and ten comparators are required. In this way, the circuit scale increases in proportion to the number of transparent colors to be set. It is possible to perform the above-described comparison process in time division by providing only one comparator for a plurality of transparent color registers. In this case, however, the number of process cycles increases.
SUMMARY OF THE INVENTION
The present invention is made to solve the above-described problems, and it is an object of the present invention to provide an image data composition apparatus which can increase the number of settable transparent colors without increasing the circuit scale and the processing cycle.
Other objects and advantages of the invention will become apparent from the detailed description that follows. The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the scope of the invention will be apparent to those of skill in the art from the detailed description.
According to a first aspect of the present invention, there is provided an image data composition apparatus comprising: a color table in which color data for each of plural color codes is associated with transparency data relating to the transparency of this color data, the color table receiving first image data which has data relating to the color of an image as the color code, and accepting the color code from the first image data, and outputting the color data and the transparency data
Masumoto Masayuki
Nagata Atsushi
Havan Thu-Thao
Matsushita Electric - Industrial Co., Ltd.
Razavi Michael
Wenderoth , Lind & Ponack, L.L.P.
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