Television – Format conversion – Line doublers type
Reexamination Certificate
1999-05-28
2002-05-07
Garber, Wendy R. (Department: 2614)
Television
Format conversion
Line doublers type
C348S441000, C348S445000, C348S459000, 38
Reexamination Certificate
active
06384865
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of and an apparatus for converting interlaced image data used in the National Television System Committee (NTSC) system, the phase alteration line (PAL) system, and the like, namely, an image data having a field format in which a frame consists of an even-numbered field and an odd-numbered field into image data of a resultant frame with a predetermined size.
2. Description of the Prior Art
FIG. 1
shows an outline of constitution of an image size converting apparatus described in Japanese Patent Application No. 9-347044. The apparatus includes a table generator
110
, a table memory
120
, an image decoder
130
, an original frame buffer
140
, an image converter
150
, a converted image frame buffer
160
, a display controller
170
, and a display
180
.
The table generator
110
includes a size conversion table generator
111
and a correcting position table generator
112
. The table generator
111
determines a conversion ratio, e.g., a reduction ratio in accordance with an original image size and a converted image size specified by a user to generate according to the ratio a size conversion table in which lines to be thinned out are specified. The correcting position table generator
112
generates according to the conversion ratio a correcting position table in which lines on which a filtering operation (correction) is to be conducted are specified. The tables thus created are stored respectively as a size conversion table
121
and a correcting position table
122
in table memory
120
.
The image decoder
130
includes an even-numbered field decoder
131
which decodes an image signal inputted thereto to store therein image data of the even-numbered field and an odd-numbered field decoder
132
which decodes an image signal inputted thereto to store therein image data of then odd-numbered field. Stored in the frame buffer
140
is one frame of original image associated with the image data of the even-numbered field and that of the odd-numbered field stored in the decoder
131
and
132
, respectively.
The image converter
150
includes a size converter
151
and a filter
152
. The size converter
151
reads one frame of image data from the buffer
140
and converts the data size thereof in accordance with the size conversion table
121
prepared in the table memory
120
. The filter
152
reads one frame of image data from the frame buffer
140
and filters the image data according to the correcting position table
122
stored in the table memory
120
. After the size conversion and the filtering operation, the image data is stored in the frame buffer
160
.
The display control section
170
reads one frame of converted image data from the frame buffer
160
and presents an image of the data on the display
180
at timing to display mobile images.
In the conventional image size converting apparatus configured as above, an image signal is supplied to the original image decoder
131
and a converted size specified by the user is supplied to the table generator
110
. In the table generator
110
, in accordance with the conversion ratio determined by the converted size and the original image size, the size conversion table generator
111
generates a size conversion table which specifies horizontal lines to be thinned out from the original image data (frame image). Moreover, the correcting position table generator
112
generates a correcting position table which specifies horizontal lines to be filtered in the original image data (frame image). These tables are placed in the table memory
120
.
On the other hand, in the image decoder
130
having received the image signal, even-numbered and odd-numbered field decoders
131
and
132
decode the input image signal and respectively stores therein image data of the even-numbered field and that of the odd-numbered field. Thereafter, one frame of the original image based on the image data of even-numbered and odd-numbered fields is stored in the frame buffer
140
.
When one frame of original image data is stored in the frame buffer
140
, the data is read therefrom by the image converter
150
. In the image converter
150
, the size converter
151
thins out horizontal lines of the original data as specified by the size conversion table
121
and the filter
152
filters horizontal lines of the original image data in accordance with the correcting position table
122
.
After the thinning-out and the filtering are finished as above, the resultant image data is once written in the converted image frame buffer
160
. The data is then read therefrom by the display controller
170
to be presented on the display
180
.
In addition to the image size converting apparatus, as an example of such an apparatus achieving the thinning out operation and the image compression, an image size reducing apparatus is described in Japanese Patent Laid-Open No. 9-219820. In the apparatus, original image data is formed in a frame each including an odd-numbered field and an even-numbered field in an interlaced manner. To compress the data in a vertical direction with a compression rate of N/M (N<M), the line numbers required to thin out almost uniformly (M−N) lines from successive M lines in the frame are specified in each of the odd-numbered and even-numbered fields. The original data is thinned out according to the specified line numbers. In the configuration of the apparatus, the original image can be compressed through the thinning out operation while preventing deterioration in information quality of the image.
Japanese Patent Laid-Open No. 8-314421 describes a display including a liquid-crystal display panel having 234 scanning lines and an aspect ratio of 4/3. In the display, a video signal received is thinned out to be compressed with a compression ratio of 3/4. The compressed image having an aspect ratio of 16/9 is displayed in a central zone of the panel and a mask such as a black band is displayed on 30 lines respectively over and below the displayed zone of the panel.
However, the image size converting apparatuses of the prior art are attended with problems as follows.
In the apparatus of Japanese Patent Application No. 9-347044, the even-numbered and odd-numbered field decoders
131
and
132
of the image decoder
130
decode all lines of the input image signal independently of the thinning out operation conducted later by the size converter
151
. Therefore, the decoder
130
decodes lines which are not to be displayed, namely, which are to be thinned out by the size converter
151
. That is, the decoding time is elongated by the unnecessary decoding.
Additionally, since the size conversion table
121
and the correcting position table
122
are first generated to convert the image size according thereto, there is required a table memory to store the tables
121
and
122
. This is disadvantageous in consideration of the production cost.
The above problem is also present in the apparatuses of Japanese Patent Laid-Open Nos. 9-219820 and 8-314421.
Although various proposals have been offered as technologies associated with the interlacing scanning, the above problem cannot be solved.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an image converting method and an image converting apparatus in which unnecessary processing time is required for the data decoding operation, thereby solving the above problems.
Further, another object of the present invention is to provide an image converting method and an image converting apparatus in which neither the size conversion table nor the correcting position table are required.
To achieve the above object in accordance with the present invention, there is provided an image converting apparatus for converting image data having a field format in which a frame consists of a first field and a second field into image data of a resultant frame with a predetermined size. The apparatus includes first decoding means for decoding each scanning line data of the fir
Desir Jean W.
Foley & Lardner
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