Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1998-11-06
2003-09-30
Rao, Andy (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C375S240220
Reexamination Certificate
active
06628718
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a color solid-state image-pickup camera system which picks up an image of a subject and carries out compression and decompression processes on image information that has acquired by the image pickup.
BACKGROUND OF THE INVENTION
Conventionally, color solid-state image-pickup cameras (hereinafter, referred to as CCD cameras) , which are capable of providing an image that has been picked up as a digital-image compression signal, have been well known. For example, such a color CCD camera system is disclosed in Japanese Laid-Open Patent Publication No. 184127/1995 (Tokukaihei 7-184127).
FIG. 7
is an explanatory drawing which shows the outline of the construction of this color CCD camera and its signal processing. As illustrated in
FIG. 7
, the conventional color CCD camera is provided with a color CCD unit
51
, a color-separation processing section
53
and code processing section
55
.
In this color CCD camera, image information of a subject is converted into an electric signal by the color CCD unit
51
. Then an output from each pixel of the color CCD unit
51
is outputted as an output signal S
52
which is a time-sequential electric signal. The output signal S
52
is subject to a color-separation process at the color-separation processing section
53
, and thus converted into an output signal S
54
containing a luminance signal and a color-difference signal. Thus, the color-separation process refers to a process for converting an image information signal into a luminance signal and a color-difference signal.
Thereafter, the output signal S
54
containing the luminance signal and color-difference signal is compressed in the code processing section
55
, and outputted as a compression signal S
56
. This compression makes it possible to transmit and receive the image information even by the use of transfer paths having limited transfer capacities. Thus, the image information can be utilized in, for example, TV conferences and other occasions.
Moreover, Japanese Laid-Open Patent Publication No. 37202/1997 (Tokukaihei 9-37202) discloses another camera system which differs from the above-mentioned technique of the Laid-Open Patent Publication in the sequence of the color-separation and compression processes (a system consisting of a digital camera and a reproducing device)
FIG. 8
is an explanatory drawing that shows the outline of the construction of the camera system and its signal processing in this Laid-Open Patent Publication. As illustrated in
FIG. 8
, this system is provided with a CCD unit
51
and a code processing section
61
which constitute a digital camera, and a decode processing section
63
, a color-separation processing section
65
and a color monitor
67
which constitute a reproducing device.
Here, image information, which has been converted into the signal S
52
in the CCD unit
51
, is compressed in the code processing section
61
into a compression signal S
62
prior to being subject to a color-separation process. Then the compression signal S
62
is decompressed in the decode processing section
63
, and the resulting signal is outputted to the color-separation processing section
65
as an output signal S
64
. Successively, the output signal S
64
is subject to a color-separation process in the color-separation processing section
65
, and the resulting signal is outputted to the color monitor
67
as a signal S
66
containing a luminance signal and a color-difference signal. Since this prior-art technique does not carry out a color-separation process in any of the color CCD unit
51
and the code processing section
61
which constitute a digital camera (compression apparatus), it becomes possible to miniaturize the circuit scale of the digital camera.
Referring to the color CCD camera of
FIG. 7
as an example, an explanation will be given of a color-separation process commonly used in a color CCD camera.
FIG. 9
is an explanatory drawing that shows a complementary-color filter
71
that is installed in the color CCD unit
51
. As illustrated in
FIG. 9
, the complementary-color filter
71
is designed so that filters Ma (magenta), Ye (yellow), Cy (cyan) and G (green) of respective colors are arranged in a predetermined array; and is placed in front of the color CCD unit
51
so that light from a subject is made incident on the color CCD unit
51
through the complementary-color filter
71
.
Additionally, for example, as shown in
FIG. 11
, the color CCD unit
51
may be provided with a complementary-color filter
72
in which filters W (white), Ye (yellow), Cy (cyan) and G (green) of respective colors are arranged in a predetermined array.
The color CCD unit
51
, which receives light from a subject through complementary-color filter
71
or complementary-color filter
72
, and outputs a signal S
52
that corresponds to the amount of light receipt, is provided with a plurality of light-receiving elements (pixels) that are associated with the respective filters of the complementary-color filter
71
or
72
. The output of each of the light-receiving elements is inputted to the color-separation processing section
53
as image data. Here, the readout system of image data related to the pixels in the color CCD unit
51
is determined by the complementary filter used therein.
The color-separation processing section
53
generates a luminance signal Y and color-difference signals U and V based upon the signal S
52
that has been outputted from the color CCD unit
51
. Here, the principle of generation of the luminance signal Y and color-difference signals U and V will be described later. These luminance signal Y and the color-difference signals U and V are inputted to the code processing section
55
.
FIG. 10
schematically shows a light-receiving surface of the color CCD unit
51
; and Ma, Cy, Ye and G in this Figure respectively indicate pixels that receive light rays that have passed through the respective color filters Ma, Cy, Ye and G in the complementary-color filter
71
. In this case, assuming that pixel Ma, located on the upper left t corner in the Figure, has coordinates (0, 0), the coordinates of pixel X located at a position apart from pixel Ma by p in the vertical direction and q in the horizontal direction is defined as (p, q); thus, the output of pixel X is represented by X
pq
using matrix representation. Moreover, it is assumed, hereinafter, that the generation of the luminance signal Y and the color-difference signals U and V are carried out on a basis of pixel blocks including
8
longitudinal pixels and
8
lateral pixels in the color CCD unit
51
.
Moreover, the luminance signal Y and the color-difference signals U and V are obtained based upon outputs from
4
adjacent pixels. Here, it is assumed that the luminance signal Y and the color-difference signals U and V are outputted from corresponding lattice points of the
4
pixels. For convenience of explanation, assuming that, among the lattice points shown in
FIG. 10
, the uppermost left lattice point (a point surrounded by pixels (p, q)=(0, 0), (1, 0), (1, 1) and (0, 1)) has coordinates (0, 0), the coordinates of a lattice point located at a position apart from said lattice point by i in the vertical direction and j in the horizontal direction is defined as (i, j); thus, the outputs of the luminance signal Y and the color-difference signals U and V, outputted from the lattice point in this position, are represented by luminance signal Y
ij
and color-difference signals U
ij
and V
ij
, using matrix representation.
In the case when complementary filter
71
shown in
FIG. 9
is used as the complementary filter, the pixel data of the color CCD unit
51
is read out by means of the 2-line-addition readout system. Therefore, as shown in
FIG. 10
, lattice points in the vertical direction exist on every other lines. In contrast, in the case when complementary filter
72
shown in
FIG. 11
is used as the complementary filter, the pixel data of the color CCD unit
51
is read out by means of the all-pixel independent readou
Birch Stewart Kolasch & Birch, LLP.
Rao Andy
Sharp Kabushiki Kaisha
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