Television – Special applications – Film – disc or card scanning
Reexamination Certificate
1997-02-19
2001-07-24
Boudreau, Leo (Department: 2721)
Television
Special applications
Film, disc or card scanning
C348S459000
Reexamination Certificate
active
06266081
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital image data storage apparatus, a digital image data transfer apparatus and a digital image data broadcast apparatus including image an data encoder and decoder.
2. Description of the Prior Art
A Conventional encoding process for interlace-scanned image data for storing and transferring is shown in
FIGS. 20A and 20B
.
FIG. 20A
is a block diagram of a process of image data compression, and
FIG. 20A
is a block diagram of a process of image data decompression. For compressing interlace-scanned image data, original image data should be generated line by line from each field, the composite image data is divided into N*N pixel blocks, then those blocks are encoded by the method of the Discrete Cosine Transformation (DCT), which is a two-dimensional orthogonal transformation. Usually signal energy of the image data is biased at low frequency, and it is expected that high frequency components are transformed to “0” by applying the DCT and proper quantization. Therefore, highly efficient image data compression can be achieved by nullifying those components.
However, if objects in the image data exhibit rapid motion, the first field and second field of the composite image data are less related. Therefore, non-“0” components can appear more in the high frequency range even after applying the DCT and proper quantization. The total amount of available bits allotted as bits for coding the compressed data is fixed in the encoding process, and compressing efficiency may be decreased by allotting the available bits to those non-“0” components in the high frequency range.
Therefore, in case when objects in the image data exhibit rapid motion, better compression efficiency can be achieved by applying the DCT to each field independently. For example, digital video recorders usually have a function for selecting the frame DCT or the field DCT in advance by detecting that the block data is “static block data” with less motion or “motion block data” with more motion.
However, there is a problem in the above-mentioned conventional method in case the image data with more motion is captured and displayed as static image data on a monitor.
Big gaps at the edge of an image in the horizontal direction between each field will appear in the motion block data of interlace-scanned image data as shown in FIG.
22
. Therefore, if it is displayed as a static image on the monitor without any adjustment, the displayed image will be deformed at the edge. In a worst case, the original image cannot be recognized because of this deformation.
One method to settle this problem is shown in JP Laid Open Patent Application No.H5-30496. According to Application No.H5-30496, gaps are compensated for by means of sliding and matching both fields spatially in the horizontal direction for reducing the deformation.
However, spatial matching of both fields requires motion vectors between fields. Calculation of the motion vectors using hardware requires special additional circuits, which lead to cost increases. Similarly, calculation of the motion vectors using software leads to processing time increases.
SUMMARY OF THE INVENTION
The invention provides an image data processing apparatus having high quality image display capability without deformation and having high compression efficiency when displaying interlace-scanned motion block data or motion frame data as a static image.
A first aspect of the image data processing apparatus of the present invention is characterized by means for reproducing and supplementing field data of one side from field data of the other side and completing frame data by compositing a base field data and a reproduced field data during data processing for displaying data as static image.
A second aspect of the image data processing apparatus of the present invention is characterized by means for controlling the applied field data supplementation for input image data according to added inter-field motion information and means for compositing frame data as the static image. The inter-field motion information is determined by means of an inter-field differential value of each block, which, if it is larger than a set value, this block data is detected as a motion block data, whereas if it is smaller than a set value, this block data is detected as a static block data.
A third aspect of the image data processing apparatus of the present invention is characterized by means for interlacing input image data, compressing the interlaced image data, decompressing the compressed image data, supplementing interlaced field data of the decompressed image data and composing frame data of a static image. The compression is a means by which the input data are divided into blocks and transformed by the DCT. The supplementation is a means by which interlaced field data are calculated from field data from the other side
A fourth aspect of the image data processing apparatus of the present invention is characterized by means for compressing original input image data by transformation. The transformation is a way to detect motion block data from input block data, calculating added value and differential value of contiguous fields, and applying the orthogonal transformation to the differential value in order to make components in the high frequency range be “0”.
A fifth aspect of the image data processing apparatus of the present invention is characterized by means for decompressing compressed image data according to the inter-field motion information. The compression can use either the spatial orthogonal transformation or a spatial-temporal orthogonal transformation on input image data depending on the accompanying inter-field motion information. Furthermore, in the case of a motion block, the decompression regards the temporal components at high frequency range as “0” and applies the inverse spatial-temporal orthogonal transformation.
A sixth aspect of the image data processing apparatus of the present invention is characterized by means for controlling decompression by the accompanying motion information and the playback type information specifying that data displayed should be motion picture or static image. The inter-field motion information is information which describes block data as a motion block or a static block. The decompression is a means for applying the usual inverse spatial-temporal orthogonal transformation to motion block data in the case that the playback type information is “motion picture”, and for applying the inverse spatial orthogonal transformation to one field of motion block data in order to compose frame data in the case that the playback type information is “static image”.
According to these and other aspects and advantages of the invention, when decompressing and displaying the compressed interlace-scanned motion picture data as a static image, deformation of the image can be reduced by using one side of field data and supplementing with the other side of field data. Because one side of field data is used, many bits can be allotted for encoding each block in compression and better quality of image display is possible.
During decompression, temporal components in motion block data are regarded as “0”, and image deformation related to motion can be reduced. Furthermore, temporal components in motion block data are regarded as being “0” in compression, and many bits can be allotted to higher use for the decompression process, resulting in a better quality image display.
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Amano Youichi
Fujiwara Yuji
Iketani Akira
Juri Tatsuro
Nishino Masakazu
Azarian Seyed
Boudreau Leo
Matsushita Electric - Industrial Co., Ltd.
Morrison & Foerster / LLP
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