Patent Application
20080063308
A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.
Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, a frame interpolating circuit comprising: a detecting unit which detects a first frame image and a second frame image from an input image signal and compares both the images with each other to detect a plurality of motion vectors in the frames; a limiting unit which limits values of the detected motion vectors in predetermined regions in the frames to a value equal to or smaller than a predetermined value; and an interpolated frame generating unit which generates and outputs an interpolated frame on the basis of said plurality of motion vectors from the detecting unit, the motion vectors the values of which are limited and which are output from the limiting unit, and the first frame image and the second frame image.
An embodiment of the present invention provides a frame interpolating process apparatus, a frame interpolating process method, and a display apparatus which stably display a still image such as a logo of a broadcast station displayed at a corner or the like of a screen.
One embodiment for achieving the object is a frame interpolating circuit comprising:
a detecting unit (12) which compares a first frame image (F1) and a second frame image (F2) from an input image signal (I1) with each other and detects a plurality of motion vectors in the frames;
a limiting unit (13) which limits values of the detected motion vectors in predetermined regions (ALU1 to ALU3) in the frames to a value equal to or smaller than a predetermined value; and
an interpolated frame generating unit (14) which generates and outputs an interpolated frame (F3) on the basis of said plurality of motion vectors from the detecting unit, the motion vectors the values of which are limited and which are output from the limiting unit, and the first frame image and the second frame image.
In this manner, there are provided a frame interpolating process apparatus and a frame interpolating process method which stably display a still image such as a logo of a broadcast station displayed at a corner or the like of a screen.
An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.
<Frame Interpolating Circuit according to One Embodiment of the Present Invention>
(Configuration and Basic Operation)
First, an example of a frame interpolating circuit according to an embodiment of the present invention will be described below with reference to
A basic operation of the frame interpolating circuit 1 will be described below in detail.
By the functions of the motion vector detecting unit 12, as shown in
The interpolated frame generating unit 14 receives a plurality of motion vectors, the vector values of which are partially limited, from the in-screen region determining/vector value limiting circuit 13 and generates an interpolated image (F3) on the basis of the past frame image (F1) and the present frame image (F2) from the input image signal (I1) to output the interpolated image (F3) to the frame memory 11. The frame memory 11 outputs the past frame image (F1), the interpolated image (F3), and the present frame image (F2) to the subsequent part in the order named.
A defect of a logo or the like appearing on a screen and an operation of a vector limiting circuit which eliminates the defect will be described below in detail with reference to the accompanying drawings.
(Operation of Vector Value Limiting Circuit 13)
Defective Display of Logo or the Like
In the motion vector detecting unit 12, as a motion vector detecting method using block matching, the following method or the like is used. That is, a block having a predetermined shape is parallel moved symmetrically about a point on two former and later frames which sandwich an insertion position of an interpolated frame image, differences of pixel values of pixels at the corresponding positions are calculated with respect to all pixels in the block to calculate an accumulated value (SAD: Sum of Absolute Difference) of the differences, and a direction in which the SAD value is minimum is used as a motion vector of the block.
In the block matching method which checks similarity of the entire block to estimate a motion vector, a broadcast station logo “ABC” or the like subjected to a blend process and shown on a normal video image as shown in
Concrete Example of Clipping Process (Limiting Process)
As a countermeasure against such defective display of the still image such as the logo, a method of clipping a vector value (properly regulated to be equal to or smaller than a predetermined value and fixed) with respect to a specific region and processing a logo image as a still image is preferably performed.
More specifically, a logo or the like of a broadcast station is mostly shown at one of the four corners of a screen not to disturb a video image. In general, a video image interested by a viewer is present at a center of the screen. For this reason, the viewer rarely pays attention to the peripheral portion of the screen. A main object of interpolated frame formation is to improve moving image blur. However, in consideration of the above point, it is understood that an effect of improving a moving image blur sensed by the viewer is large at the center of the screen and small at the peripheral portion of the screen. However, on the other hand, a sensitivity to the feeling of moving image blur at the peripheral portion of the screen is not high, but a sensitivity to an erroneously interpolated video image at the peripheral portion of the screen is high to some extent. This is recognized as a broken video image.
A limiting process according to an embodiment of the present invention has been made in consideration of the above point. In an interpolated frame forming method which detects a motion vector, an interpolated frame is formed by using a vector, the detected vector value of which is clipped to a predetermined value in a specific region in one screen (limited to be equal to or smaller than a predetermined value as needed). In this manner, a video image is suppressed from being broken by erroneously interpolating the broadcast station logo or the like while keeping the effect of improving moving image blur.
The process will be described below by citing concrete numerical values.
It is assumed that, as an amount of motion between a former frame and a rear frame, motion up to 20 pixels in a horizontal direction and up to 8 pixels in a vertical direction is detected by block matching. In this case, an entire input video image moves at 16 pixels/frame to the right in the horizontal direction and 6 pixels/frame on the upper side in the vertical direction, and it is a semitransparent broadcast station logo standing still at the upper left corner of the screen is shown on the video image. In the following description, a motion vector to be detected is expressed as a moving distance of an object within transition time from the former frame to the interpolated frame or the interpolated frame to the rear frame.
When the video image is input, a motion vector having 8 pixels in a nearly horizontal direction and 3 pixels in a vertical direction is detected in a region in which a logo is not shown by the block matching process. In a region on which the logo is shown, a result depends on luminance and color components of a background video image and luminance and color components of the logo. As in the region on which the logo is not shown, the embodiment will be described below with reference to an example in which a motion vector having 8 pixels in a horizontal direction and 3 pixels in a vertical direction is detected.
In the interpolated frame forming method in which no clipping process (value is limited to be equal to or smaller than a predetermined value as needed) is performed, a motion vector detected by block matching is directly used to form an interpolated frame.
Therefore, as described above, a frame which is erroneously interpolated like ghost at an obliquely upper portion or an obliquely lower portion of the original logos as shown in
In order to solve this problem, in a clipping process for a vector value (limited to be equal to or smaller than a predetermined value as needed), as shown in
In this manner, noise like ghost generated around the logo is reduced. On the other hand, with respect to a background video image actually moving, motion correction is erroneous. For this reason, the feeling of blur is stronger in the clipping process (limiting process) than in a normal process. However, as described above, it can be said in a comprehensive manner that an influence by the increase of the feeling of blur is small.
Here, when an amount of clip of a motion vector is sharply changed, the image looks unnatural at the boundary portion. For this reason, as shown in
In the embodiment, more specifically, for example, a motion vector detected in the region ALU1 closest to the corner on the upper left of the screen is clipped by 2 pixels in the horizontal direction and one pixel in the vertical direction, a motion vector detected in the region ALU2 first next to the region ALU1 is clipped by 4 pixels in the horizontal direction and 2 pixels in the vertical direction, a motion vector detected in the region ALU3 first next to the region ALU2 is clipped in 6 pixels in the horizontal direction and 3 pixels in the vertical direction, and motion vectors detected by the vector detecting unit are directly used in the other regions.
In this manner, while maintaining the effect of improving motion vector blur, a broken video image generated by erroneously interpolating a broadcast station logo or the like can be reduced.
A method of changing a clip value of a motion vector is not limited to the example. In addition to a motion having an accuracy in units smaller than pixels such as an accuracy in units of 0.5 pixels, the clip value can also be changed in finer steps.
By the clipping process (reducing process) of a vector value, breakdown caused by erroneous detection of a motion vector can be reduced with respect to a video image including a broadcast station logo or the like.
As another embodiment of the clipping process (reducing process) of the vector value limiting circuit 13 described above, when the four corners of a frame are used as specific regions as shown in
More specifically, as shown in
As shown in
<Panel Display Apparatus Using Frame Interpolating Circuit According to One Embodiment of the Present Invention>
An example of a panel display apparatus using the above frame interpolating circuit will be described below in detail with reference to
A panel display apparatus 30 using a frame interpolating circuit 1 has, as an example, a tuner unit 31 which outputs a broadcasting signal as a video signal, a scaler 32 which performs scaling process of the video signal, an IP converting unit 33 which performs IP conversion of the video signal, a processing unit 34 which includes color management, enhancer, a correcting circuit, and the like, the frame interpolating circuit 1 described above, and a panel unit 15 such as a liquid crystal display unit or an FPD (Flat Panel Display) which receives an output from the frame interpolating circuit 1.
The panel display apparatus 30 having such a configuration causes the frame interpolating circuit 1 to perform a clipping process (limiting process) of vector values in specific regions such as four corners as described above to make it possible to display a still image such as a logo without breakdown. For this reason, a smooth and natural video image can be displayed by using an interpolated frame without breaking the video image.
According to various embodiments described above, a person skilled in the art can realize the present invention. The person skilled in the art can conceive of various modifications of the embodiments and can apply the present invention to various embodiments without inventive ability. Therefore, the present invention covers in wide ranges consistent with the disclosed principle and the novel characteristics, and is not limited to the embodiments described above.
While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-244461 | Sep 2006 | JP | national |
