Computer graphics processing and selective visual display system – Computer graphics processing – Attributes
Reexamination Certificate
2002-07-26
2004-08-17
Bella, Matthew C. (Department: 2676)
Computer graphics processing and selective visual display system
Computer graphics processing
Attributes
C345S690000, C345S022000, C345S055000, C358S518000, C382S167000
Reexamination Certificate
active
06778184
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a field of drive control of a display apparatus. Specifically, the present invention relates to a color signal correction circuit, a color signal correction apparatus, a color signal correction method, and a color signal correction program, which are used for color signal correction in a display apparatus, and also relates to a display apparatus in which such color signal correction can be realized.
2. Description of the Related Art
The performance of a color display device used for an electronic apparatus or the like has been improving on a year-by-year basis. This trend is found not only in a large size display device incorporated in a liquid crystal TV, or the like, but also in a small size display device incorporated in a portable apparatus, such as a portable telephone, a portable game apparatus.
For example, in a conventional portable game apparatus, an image is displayed based on a low-resolution color-scale color signal, such as an animation image. However, recently, consumers have demanded high-quality color image displays, for example, of an image which looks like a natural picture where an object within a three-dimensional space is expressed with shadows. For the purpose of satisfying such a demand, it is necessary to provide some means to allow a color signal of higher-resolution color-scale (multiple color-scale levels) to be used in a display apparatus and a control circuit thereof.
Herein, a “color signal” refers to display data (color component data), such as an image displayed on pixels arranged in a matrix over a display apparatus, i.e., a color-scale representation value which is used for controlling the brightness of the pixels.
A conventional liquid crystal display apparatus has the following structure.
FIG. 11
is a block diagram showing the structure of a conventional liquid crystal display apparatus. The liquid crystal display apparatus
101
includes: a liquid crystal display module
7
; an external host system
8
; and a system bus
9
which connects the liquid crystal display module
7
and the external host system
8
. The liquid crystal display module
7
includes a liquid crystal display panel unit
11
, a liquid crystal driving controller
12
(hereinafter “LCDC”), and a display memory
13
. The external host system
8
includes a CPU
15
; a system memory
16
, and an I/O system
17
.
For example, the liquid crystal display panel unit
11
includes: a TFT-type liquid crystal panel having pixels arranged in a matrix; a source driver for applying to a TFT source line of the liquid crystal panel a color-scale representation voltage, which is determined based on image display data generated for driving the liquid crystal panel; a gate driver for applying a scan control signal to a TFT gate line of the liquid crystal panel; and a liquid crystal driving voltage generation circuit for generating the color-scale representation voltage. In the case where the liquid crystal display panel unit
11
includes a STN-type liquid crystal panel, a segment driver and a common driver are used in place of the above source and gate drivers.
The LCDC
12
is a controller circuit which generates, under the control of the external host system
8
, a control signal for controlling the source driver and the gate driver and an image display signal (data) to be supplied to the source driver. The LCDC
12
further includes: an interface section
21
for transmission of signals and data with the external host system
8
and the display memory
13
; and a signal processing section
22
for reading image display data from the display memory
13
and generating a control signal to be supplied to the source driver in the liquid crystal display panel unit
11
.
The LCDC
12
outputs: a transfer clock signal for transferring image display data; a source driver start pulse signal (horizontal synchronization signal) for controlling the start of transfer of the image display data based on the unit of a horizontal synchronization period; a gate driver start pulse signal (vertical synchronization signal) for controlling the start of scanning of a scan control signal; and a control signal, such as an alternating signal used for performing an alternating driving of the liquid crystal panel.
The external host system
8
is a commonly employed CPU system which transfers the image display data, which has been externally input through the I/O system
17
, to the liquid crystal display panel unit
11
, and controls the liquid crystal display module
7
via the system bus
9
.
Recently employed liquid crystal display panel units include a TFT-type liquid crystal display panel unit which performs color-scale representation corresponding to image display data consisting of 18 bits in total. In this liquid crystal display panel unit, color image display data is data of 64 color-scale levels (=2
6
) where 6 bits are allocated to each of R (red), G (green), and B (blue) pixels, each of which corresponds to 1 dot. The liquid crystal display module including this liquid crystal display panel unit is controlled using a CPU system which includes a commonly-employed, general purpose control processor, rather than a special purpose control processor, as an external host system. This is because the CPU system which includes the commonly-employed, general purpose control processor is less expensive, and can be used for various purposes.
The bit number of data which can be used in such a general purpose control processor is a multiple of 8 (i.e., 4), i.e., 8 bits, 16 bits, 24 bits, 32 bits, etc.
As of now, image display data consisting of 16 bits can express a color image by 65536 (=2
16
) colors. In a color data pattern used for this image display data, a 5-6-5 format is generally employed. In the 5-6-5 format, as color-scale representation values, 5 bits are allocated to R, 6 bits to G, and 5 bits to B, so as to obtain image display data consisting of 16 bits in total.
In a TFT-type liquid crystal display panel unit, as described above, 6 bits are allocated as a color-scale representation value to each of R, G, and B, so as to obtain a uniform bit structure. That is, image display data to be processed consists of 18 bits in total.
Thus, in the liquid crystal display module
7
shown in
FIG. 11
, if image display data output from the external host system
8
and input to the LCDC
12
through the system bus
9
has a 16-bit structure, this data must be converted or corrected in the signal processing section
22
of the LCDC
12
into image display data consisting of 18 bits in total, where 6 bits are allocated as a color-scale representation value to each of R, G, and B.
Thus, in the signal processing section
22
of the LCDC
12
, in order to obtain conformity between image display data consisting of 18 bits and image display data consisting of 16 bits, the image display data of 16 bits is subjected to color-scale correction such that 5-bit image data allocated to each of R-pixel and B-pixel is expanded to 6-bit image display data.
Conventional techniques of such color-scale correction are explained below:
(1) LSB (Least Significant Bit) Fixed Method
In this method, 1 bit is newly added as a least significant bit (LSB) to 5-bit image display data so as to obtain 6-bit data, and this new LSB is set to “1” or “0” by default.
(2) MSB (Most Significant Bit) Repetition Method
In this method, 1 bit is newly added as a least significant bit (LSB) to 5-bit image display data so as to obtain 6-bit data, and a value equal to data of the most significant bit is set as data of the least significant bit (LSB).
(3) Color-Scale Palette Method
In this method, the relationship between 5-bit image display data and 6-bit image display data is established in the form of a palette (also referred to as a “look up table (LUT)” or a “conversion table”). When certain image display data is input, image display data corresponding to the input image display data is output.
However, all of the above methods have a problem in color
Aoki Toshiya
Arita Kazuyuki
Bella Matthew C.
Sajous Wesner
Sharp Kabushiki Kaisha
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