Television – Format conversion – Line doublers type
Reexamination Certificate
1998-11-12
2001-07-31
Kostak, Victor R. (Department: 2611)
Television
Format conversion
Line doublers type
C348S452000
Reexamination Certificate
active
06268886
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital TV and more particularly to an apparatus and method for converting a picture scanned in the interlaced scanning pattern to a picture scanned in the progressive scanning pattern.
2. Discussion of Related Art
Generally, a picture of a digital TV may be scanned on a monitor by an interlaced scanning pattern or a progressive scanning pattern. Some display monitors requires one type of scanning pattern while the picture is received in another type of scanning pattern. A deinterlacing apparatus is used to convert a picture scanned in the interlaced scanning pattern to a picture scanned in the progressive scanning pattern, filling the pixel value omitted in one field to provide a perfect frame.
For example, a deinterlacing apparatus is required to display TV signals on the monitor of a computer. Because the computer monitor supports the progressive scanning system and the TV signal such as NTSC supports the interlaced scanning system, the TV signal of the interlaced scanning system must be converted to signals in the progressive scanning system in order to view the picture on the computer monitor.
To fill the pixel values omitted in a field and complete one frame, the deinterlacing apparatus and method employs interpolation in the field, interpolation in the field or compensation between the fields through motion detection, or compensation between the fields using motion vectors through motion estimation. A deinterlacing apparatus and method employing interpolation in just the field is used for a very simple system.
FIGS. 1
a
through
1
c
are diagrams illustrating a grand-alliance deinterlacing procedure according to prior art, in which the grand-alliance deinterlacing procedure is adopted to perform interpolation in the field and compensation between the fields by way of motion detection.
FIGS. 2
a
and
2
b
illustrate a deinterlacing procedure employing motion compensation according to the prior art, in which the deinterlacing procedure is adapted to perform compensation between the fields using motion vectors via motion estimation.
In the deinterlacing procedure employing motion detection recommended by the HDTV standards of the North American area, pixels A to H adjacent a pixel to be filled are determined as shown in
FIG. 1
b.
The location of these pixels are used to calculate E
1
=|F−C|, E
2
=|(D+E)/2−(A+B)/2| and E
3
=|(D+E)/2−(G+H)/2|. The largest one of the values E
1
, E
2
and E
3
is set to E
max
for motion detection. The value of E
max
is then compared with thresholds T
1
and T
2
to determine the value of ∝, as shown in
FIG. 1
c,
in which ∝ is the weight for interpolation in the field and 1−∝ is the weight for compensation between the fields. After determining the weights for interpolation in the field and compensation between fields, the value of the omitted pixel as shown in
FIG. 1
a
is calculated as ((D+E)/2)*∝+C*(1−∝) and other omitted pixels are also filled in a similar way.
The deinterlacing apparatus employing interpolation in both the field and compensation between the fields provides progressive pictures of high quality relative to a deinterlacing apparatus that performs interpolation in just the field. However, it is difficult to determine the thresholds values T
1
and T
2
used to calculate the weights for interpolation in the field and compensation between the fields.
If the threshold T
1
has an extremely small value, the interpolation in the field prevails over compensation between the fields and does not achieve a high quality picture. On the contrary, a too large threshold T
2
makes the compensation between the fields prevail over the interpolation in the field. The heavy weight in the compensation between the fields may be better for a still picture, but performs interpolation with erroneous pixel values for a moving picture causing deterioration of picture quality.
FIGS. 2
a
and
2
b
shows a deinterlacing procedure using motion vectors to perform compensation between the fields via motion estimation. As shown, a motion estimating section
21
searches for motion of an input picture to determine the pixels most likely omitted from pixels A to L, and a deinterlacing section
22
fills the omitted pixels with pixels indicated by the motion vector.
However, a picture produced by a deinterlacing procedure using motion vectors has much errors in the motion estimation due to its poor vertical resolution. Also, the motion estimating procedure is extremely complex, requiring many calculations in the deinterlacing section
22
, which raises the cost of filling the omitted pixels.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the related art.
Particularly, an object of the present invention is to provide a picture format converting apparatus and method to achieve a high quality picture with minimal cost.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purposes of the invention, as embodied and broadly described herein, a picture format converting apparatus and method according to the present invention analyzes the information of each picture obtained by decoding a compressed input picture scanned in an interlaced scanning pattern and performs motion-adaptive interpolation of the picture in an adaptable manner according to the analysis result.
One embodiment of the present invention includes a picture characteristic extracting section for analyzing a compressed bit stream of every input pictures scanned in an interlaced scanning pattern to analyze the characteristic of each picture; an interpolation determining section for determining an interpolation operation processing in an adaptable manner using information extracted for every given pictures at the picture characteristic extracting section; and an operation performing section for performing the related operation according to the interpolation operation processing determined by the interpolation determining section to perform an interpolation.
The picture characteristic extracting section according to the present invention includes a decoding section for decoding the compressed bit stream of the input picture scanned in the interlaced scanning pattern to extract the individual characteristics of macro blocks of each frame and the entire characteristic of each frame; and a threshold determining section for determining thresholds by use of the characteristics extracted by the decoding section based on the type of the frame in order to employ compensation between fields or interpolation in the field properly.
In an another embodiment of the present invention, a method for converting a picture format in a digital TV includes the steps of analyzing a compressed bit stream of every input pictures scanned in an interlaced scanning pattern to analyze the characteristic of each picture; determining an interpolation operation processing in an adaptable manner using information each extracted for every given pictures; and performing the related operation according to the determined interpolation operation processing to perform an interpolation.
The step of analyzing the characteristic of the picture according to the present invention includes extracting the coding type of each macro block, right/counter directional motion vector, and the DCT coefficient of the original or differential picture; comparing the number of intra-coded blocks with the number of blocks coded through motion c
Fleshner & Kim LLP
Kostak Victor R.
LG Electronics Inc.
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