Computer graphics processing and selective visual display system – Display driving control circuitry – Display power source
Reexamination Certificate
2001-07-23
2004-06-08
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Display driving control circuitry
Display power source
C345S098000, C345S660000
Reexamination Certificate
active
06747640
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image display device comprising a matrix display device such as an LCD (liquid crystal display), PDP (plasma display panel), or DMD (digital micro-mirror device) and to an image display method, and more particularly relates to an art for enlarging and reducing images for displaying image signals on a display device having a higher or lower number of pixels.
2. Description of the Related Art
First, description will be made regarding image scaling processing as an example of image enlarging processing, following which description will be made of memory control accompanying processing in the vertical direction.
Here, an x-y orthogonal coordinates system will be used to describe the relation between the original image and the image following the enlarging processing (post-conversion image) with the x coordinates in the horizontal direction and the y coordinates in the vertical direction. The original image is sampled in the horizontal direction and vertical direction, and is made up of image data which is m pixels in the horizontal direction and k pixels in the vertical direction.
Let us consider a case of taking the image data made up of the m×k pixels and enlarging the data into image data made up of M×K pixels, M pixels in the horizontal direction and K pixels in the vertical direction.
FIG. 1
is a diagram schematically illustrating the relation between the original image and the image following enlarging conversion (post-conversion image). In the enlarged example of this image, the original image made up of m×k pixels is converted into an image made up of M×K pixels. In the drawings, the white dots indicate pixel data of the original image. The solid dots in the post-conversion image indicate image area in the post-conversion image provided based on the white dot pixel data in the original image. In this case, the ratio of enlargement in the horizontal direction is M/m, and the ratio of enlargement in the vertical direction is K/k.
In order to study the relation between the pixels of the original image and the pixels of the post-conversion image, reverse mapping will be performed wherein the coordinates of the post-conversion image are correlated to the coordinates of the original image.
FIG. 2
is an example of reverse mapping of the pixel D in the post-conversion image to the coordinates in the original image.
In this figure, the white dots indicate pixels in the original image, and the solid dots indicate pixels in the post-conversion image which has been reverse-mapped. For the sake of simplicity, let us say that the pixels of the original image are adjacent by a distance of 1 in the horizontal direction and the vertical direction, with the pixel data being represented by the format of d(x, y). Here, x and y are integers.
In this example, an interpolating pixel D of the post-conversion image is reverse-mapped to coordinates wherein an area consisting of the four surrounding points of d(x, y), d(x+1, y), d(x, y+1), and d(x+1, y+1), is divided by the ratio of p:1−p in the horizontal direction and q:1−q in the vertical direction, wherein 0≦p<1 and 0≦q<1 hold. In this case, the coordinates of the reverse-mapped interpolating pixel D are expressed as (x+p, y+q).
In the event of a linear interpolating filter for example, the above p and q, and the four surrounding points of d(x, y), d(x+1, y), d(x, y+1), and d(x+1, y+1) around the interpolating pixel D yield the pixel data of the interpolating pixel D by calculation expressed as the following Mathematical Expression 1.
D
=(1
−p
)·(1
−q
)·
d
(
x, y
)+
p
·(1
−q
)·
d
(
x+
1
, y
)+(1
−p
)·
q·d
(
x, y+
1)+
p·q·d
(
x+
1
, y+
1) [Mathematical Expression 1]
Now, description will be made regarding the scaling processing of the image in the vertical direction. Here, we will study an example of enlarging processing in the vertical direction for converting five lines into eight lines, as an example for description.
FIG. 3
is a diagram illustrating the manner in which coordinates in the post-conversion image are correlated to coordinates in the original image, with regard to the vertical direction. In the figure, the white dots and d represent image data of the original image, and d(0) represents image data on the line 0 in the original image.
Pixels d(0), d(1), d(2), and so forth of the original image are adjacent by a distance of 1. Also, the solid dots and D represent image data of the post-conversion image. D(0) represents image data in line No. 0 in the post-conversion image.
In the items shown in this figure, the five lines of the original image and the eight lines of the post-conversion image correlated, so the image data D of the post-conversion image naturally has spacing of ⅝=0.625 as compared to that of the image data of the original image. Representing the position of the image data of the post-conversion image by coordinates of the original image expresses D(0) as being 0.0, D(1) as 0.625, and D(2) as 0.625×2=1.250.
Now, looking more closely at the image data D(2) of the post-conversion image, the coordinate thereof is 1.250, at a position dividing the coordinate of the line data d(1) and d(2) of the original image by a ratio of 0.25 to 0.75. That is to say, in the event of using linear interpolation, for example, the image data D(2) of the post-conversion image can be obtained by D(2)=0.75×d(1)+0.25×d(2), from the image data d(1) and d(2) of the original image.
The line data D(0) and D(1) of the post-conversion image are calculated from the image data d(0) and d(1) of the original image. Also, D(2) and D(3) are calculated from d(1) and d(2). In the same way, D(4) is calculated from d(2) and d(3), and D(5) and D(6) are calculated from d(3) and d(4).
In the event that such a correlating relation between the line data of the original image and the line data of the post-conversion image are satisfied, scaling processing of the image is carried out normally. Incidentally, in the event of performing computation by image data on multiple lines as described above, a method is used wherein multiple lines of image data are read out using memory provided within the device.
FIG. 4
is a timing chart showing a case of performing image scaling processing in the vertical direction using line memory for three lines. This example also involves enlarging processing for converting five pixels into eight pixels, for the sake of explanation.
In the figure, the symbol (a) represents horizontal synchronizing signals of the input image signals, and (b) represents image data of the input image signals (i.e., original image data). The symbols (c), (d), and (e) represent write addresses and read addresses in the three lines of memory (wherein time passes in the direction of traveling right in the figure, and the address values of each increase with the passage of time).
The symbol (f) represents horizontal synchronizing signals of the output image signals. Now, let us say that the output image signals are image signals containing post-conversion image data. The symbols (g), (h), and (k) represent image data read out from the line memory.
In (a), Th represents the cycle of the horizontal synchronizing signals in the input image signals, and y, y+1, y+2, and so forth represent line position in the input image signals. In (b), d(y), d(y+1), d(y+2), and so forth represent image data corresponding to the line positions y, y+1, y+2, and so forth.
In (c), (d), and (e), the vertical axis represents addresses, with the dotted lines representing write addresses and the solid lines representing read addresses. In (f), Tid represents the cycle of the horizontal synchronizing signals in the output image signals, and Y, Y+1, Y+2, and so forth represent line position in the image signals of the post-conver
Okuno Yoshiaki
Someya Jun
Hjerpe Richard
Lesperance Jean
Mitsubishi Denki & Kabushiki Kaisha
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