Interactive video distribution systems – Operator interface
Reexamination Certificate
1997-06-03
2001-10-30
Faile, Andrew (Department: 2611)
Interactive video distribution systems
Operator interface
C348S561000, C348S581000, C348S458000, C345S182000, C345S182000, C358S451000, C382S298000, C382S300000
Reexamination Certificate
active
06311328
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a picture processing apparatus that allows a picture to be enlarged/reduced at any ratio and that is used for a special effect unit in a broadcasting station or the like, a television receiver, or a video tape recorder and to a picture processing method.
2. Description of the Related Art
In home-use television receivers, a so-called picture-in-picture system and the picture-and-picture system of which a reduced or enlarged screen is displayed along with an original screen has been practically used. The picture-in-picture consists of a smaller sub picture than the main picture framed and displayed on an original screen (main picture). On the other hand, the picture-and-picture consists of a plurality of a small pictures arranged and displayed. In the picture-in-picture system and the picture-and-picture system, another screen is reduced or enlarged at any fixed ratio that is a multiple of the size of the original screen. Thus, by simply filtering and thinning out pixels of an original screen to be reduced (enlarged), a reduced or enlarged picture can be obtained almost without deterioration of the picture quality thereof.
FIG. 5
shows an example of the structure of a filter for reducing/enlarging a picture corresponding to a prior art reference. In
FIG. 5
, a horizontal interpolating filter
101
is a low-pass filter. The horizontal interpolating filter
101
is composed of one-pixel delaying devices D, coefficient multiplying devices, and an adding device. A vertical filter
102
is low-pass filter. The vertical filter
102
is composed of one-line delaying devices H, coefficient multiplying devices, and an adding device.
When a picture is reduced, picture data received from a terminal
100
is supplied to the horizontal interpolating filter
101
and the vertical interpolating filter
102
. The horizontal interpolating filter
101
and the vertical interpolating filter
102
interpolate the picture data in the horizontal direction and the vertical direction, respectively. Pixels of the resultant picture data are thinned out at a predetermined reducing rate and then written to a field memory
103
. When the picture size is reduced to ½ each in the horizontal direction and the vertical direction, every second pixel in the horizontal direction and every second line in the vertical direction of picture data is written to the field memory
103
. The reduced picture data is read from the field memory
103
and supplied to a terminal
104
.
When picture data is enlarged, picture data of which dummy data has been placed in the horizontal direction and the vertical direction at predetermined intervals is received from the terminal
100
. The resultant picture data is interpolated in the horizontal direction and the vertical direction and written to the field memory
103
.
In the picture reducing process for interpolating and thinning out pixels of picture data by such a filter, when the reducing ratio of the size of the original picture to the size of the reduced picture is a ratio of simple integers, pixels of picture data can be easily thinned out. Thus, the picture data can be reduced with a relatively high picture quality. This property also applies to the picture enlarging process. However, in the case that the size of a reduced picture can be freely set up, the reducing ratio does not become a ratio of simple integers. In this case, since it is difficult to equally thin out pixels, the picture quality is deteriorated. For example, inclined lines of a reduced picture are not smoothly displayed. Likewise, in the picture enlarging process, such a situation takes place. In particular, when the ratio of the size of the original picture size to the size of the reduced/enlarged picture is ½ to 1 or more than 1, the picture quality is remarkably deteriorated.
As a method for enlarging or reducing a picture at any ratio without a deterioration of the picture quality, for example a linear interpolating method is known. Now, assume that an original picture is sampled as m pixels and n pixels in the horizontal direction and vertical direction, respectively. In addition, consider the case that the picture composed of m×n pixels is enlarged to a picture composed of M pixels in the horizontal direction and N pixels in the vertical direction.
According to such a method, a reverse mapping process of which the coordinates of a converted pixel are correlated to the original coordinates thereof.
FIG. 6
shows that a pixel a of a converted picture is reversely mapped to the original coordinates thereof. The pixel shown by a black point “&Circlesolid;” shows a pixel a which is reversely mapped to the original coordinates. The pixel shown by a white point “∘” shows an original pixel. The density value of a pixel a of the converted picture (hereinafter, “density value of pixel a” is referred to as “density value a”) is obtained by multiplying the density values of the pixel a at original four adjacent points thereof by the inverse numbers of the distances between the pixel a. In other words, when the density value of the pixel at each point is represented in the form d(x, y), the density value a is expressed by the following formula (1).
a=
(1−
q
)(1−
p
)×
d
(
x,y
)+(1−
q
)
p×d
(
x+
1
,y
)+
q
(1−
p
)×
d
(
x,y+
1)+
qp×d
(
x+
1
,y+
1) (1)
With such an interpolating process, when a picture is enlarged or reduced at any ratio rather than a multiple, for example inclined lines can be smoothly displayed with less picture deterioration. With this method, the coefficients p and q should be calculated for each pixel.
FIG. 7
shows the relation between an original picture and a converted picture. In this example, the original picture composed of m×n pixels is converted into an enlarged picture composed of M×N pixels (m<M, n<N). In this case, the enlarging/reducing ratio A in the horizontal direction and the enlarging/reducing ratio B in the vertical direction are obtained by the following formulas (2) and (3), respectively.
A=N
(2)
B=M/m
(3)
By dividing the coordinates (X, Y) of a pixel of the converted picture by the converting ratios A and B, the coordinates of which the pixel is reversely mapped to the original coordinates can be obtained. Thus, as described above, the density value of a converted pixel (X, Y) is calculated corresponding to the density values of pixels at original four adjacent pixel positions (x, y), (x+1, y), (x, y+1), and (x +1, y+1) of which the pixel (X, Y) is reversely mapped to the original coordinates and to the distances between four points and the coordinates upon reversely mapping.
When the pixel (X, Y) is reversely mapped to the original coordinates, the position of the original coordinates thereof can be represented corresponding to the converting ratios A and B with the following formulas (4) and (5).
x/A=X
1
.P
x
(4)
y/B=Y
1
.q
y
(5)
In the formulas (4) and (5), X
1
and Y
1
represent coordinates of which a pixel has been converted; p
x
and q
y
represent interpolating coefficients; and “.” between X
1
and p
x
and between Y
1
and q
y
represents a decimal point. In other words, X
1
and Y
1
are integer parts of the calculated results of x/A and y/B. p
x
and q
y
that represent interpolating coefficients are decimal parts. Thus, decimal parts of which the position of a converted pixel does not accord with the position of the original pixel are used as interpolating coefficients.
FIG. 8
shows an example of the structure for enlarging/reducing a picture corresponding to such operations and the calculated results by the linear interpolating method. Memories
110
a
,
110
b
,
110
c
, and
110
d
are random access memories. Original picture data (not shown) is written to the memories
110
a
,
110
b
,
110
c
, and
110
d
. An address generating c
Miyazaki Shinichiro
Ono Takeshi
Shirahama Akira
Ueki Nobou
Brown Reuben M.
Faile Andrew
Maioli Jay H.
Sony Corporation
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