JPH03102978A - Moving picture/still picture converter - Google Patents

Abstract

PURPOSE:To obtain a clear still picture with few noises by inter-frame-noise- reducing processing a digital moving picture signal, and simultaneously, inter- frame-noise-reducing processing the same. CONSTITUTION:A motion vector is detected from every frame of the digital moving picture signal written in a picture memory 14 by a motion vector detection circuit 16, and corresponding picture areas between frames are determined by a picture area designation circuit 20, and simultaneously, flags '1', '0' are erected in a motion vector memory 18 correspondingly to the area where the motion vector was detected or the area where no motion vector was detected. Then, the corresponding pictures between the frames are smoothed by an inter-frame smoothing circuit 24, and the noise is reduced, and the picture is stored in the memory 14. Further, the group area of the flag '1' of the memory 18 is decided by a group decision circuit 22, and the picture of the area designated by the circuit 24 among frame data from the memory 14 whose noise between the frames is reduced is processed by averaging-processing, etc., and is inter-frame-noise-reduced, and is outputted, and becomes the clear still picture with few noises by two kinds of noise reduction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a moving image/still image converting device that outputs a moving image manually generated from, for example, a television camera or a VTR to a CRT or printer as a still image.

[Conventional technology] In the past, images output by printers, etc. were mainly input from still image input devices such as image scanners, but recently, input devices such as televisions, cameras, video cameras, etc. A wide variety of devices such as cameras and VTRs have come into use.

Furthermore, as the definition of television signals such as HDTV becomes higher, there is a growing tendency to output images of high-definition television signals to printers and printing devices.

Generally, when extracting one scene of a moving image such as the output of a television camera as a still image, there are still many problems in obtaining a good still image. In particular, in moving images, noise in one frame becomes difficult to see due to the integral effect of the visual system in the time axis direction, whereas in a still image extracted from one frame, the integral effect of the visual system is small, and the image quality due to noise is There is a problem in that the deterioration becomes noticeable. To deal with this, it is possible to remove noise by, for example, interframe smoothing.

[Problems to be Solved by the Invention] However, when inter-frame smoothing is performed on a moving image, positional shifts occur between frames, and as a result, not only are there parts where noise is not removed, but the image becomes unclear. become. For example, as shown in FIG. 3, suppose that a circular object is at position CA in a given frame of interest and moves to position C in the next frame. If inter-frame smoothing is performed in such a case, appropriate inter-frame smoothing will be performed on the common portion B of images CA and C, and the deterioration due to inter-frame smoothing will not be noticeable, but the non-common portion A
, C, inter-frame smoothing is performed between the target image and the background image S, resulting in blurring.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a moving image/still image conversion device that can obtain a clear still image from a moving image.

[Means for Solving the Problems] A moving image/still image conversion device according to the present invention includes a motion vector detection means for detecting a motion vector for each small region of a frame of interest of a moving image signal, a frame of interest, and a frame of interest. and a noise reduction processing means for performing noise reduction processing in the time axis direction using an image of a corresponding small area obtained by the motion vector in a different frame.

[Operation] With the above means, even in moving images, noise reduction processing is performed between the same images moved to different positions in different frames, and furthermore, noise reduction processing is performed in consideration of the presence or absence of movement within the same frame. , appropriate noise reduction processing can be performed depending on the presence or absence of movement and its degree. Therefore, it is possible to obtain a still image in which the occurrence of image blur and pseudo images is minimized.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a structural block diagram of an embodiment of the present invention. 1
0 is an interface circuit for connection to a moving image human-powered device such as a video camera or VTR, 12 is a control circuit that controls the entire sequence, 14 is an image memory that can store several frames of moving images, and 16 is an image memory that can store several frames of moving images. a motion vector detection circuit that calculates the motion vector of an image between frames;
18 is a motion vector memory that stores the detected motion vector; 20 is a motion vector memory that stores the detected motion vector;
An image region designation circuit detects and designates corresponding image regions between frames; 22 is a group determination circuit that determines characteristics of a group of image regions based on motion vectors and image data; 24 is a designated an interframe smoothing circuit that smoothes an image area between frames;
26 is an intra-frame smoothing circuit that smoothes within the frame according to the characteristics of the group; 30 is a color printer or CR
This is an interface circuit for connecting to an image output device such as T.

Next, the operation shown in FIG. 1 will be explained. When the apparatus of FIG. 1 receives an image input request, the control circuit 12 activates the interface circuit 10 and the memory control circuit 12 and grants access to the image data bus 34. The interface circuit 10 converts a moving image signal from an external moving image device into a digital signal if it is an analog signal, and outputs it to the image data bus 34 in synchronization. The image memory 20 sequentially takes in image data from the image data bus 34 and stores a number of consecutive frame images (n in this embodiment) in frame units. When n frames of images are stored in the image memory 14, the control circuit 12 deactivates the interface circuit 10 and the image memory 14 via the control bus 32, and ends the image input operation.

Next, a motion vector detection operation begins. FIG. 2 shows an example of n-frame images stored in the image memory 14. In this example, a circular object is moving on some uniform background. The control circuit 12 activates the image memory 14, motion vector detection circuit 16, motion vector memory 18, and image area designation circuit 20 via the control bus 32. For convenience of explanation, it is assumed here that an output request is made in the first frame.

The motion vector detection circuit 16 detects a small area (
Image memory l4 in units of blocks of a certain size or l pixels
The image data is read from , the motion vector Mij (unit: pixel/frame) is detected, and the motion vector memory 1 is
Store in 8. Methods for detecting motion vectors include, for example, a concentration gradient method and a matching method. Further, in this embodiment, the first frame and the m-th frame (m-2 to n) are used as two frames for detecting a motion vector. If the motion region moves outside the frame, motion vector detection becomes impossible; however, in such regions where motion vectors cannot be detected, a flag MF indicating that motion vectors cannot be detected is stored in the motion vector memory 18. stand up.

After detecting motion vectors for the entire region of the frame of interest, control circuit 12 deactivates image memory 14, motion vector detection circuit 16, and motion vector memory 18. In the example of the input image in Fig. 2, the first frame and the
If you look at the frames overlapping, it will look like Figure 3. Ideally, the motion vector of such a human image is divided into areas A and B.
In area C, it is a hidden part and cannot be detected, and in area D, it is stationary and becomes an O vector.

Next, interframe smoothing processing begins. The control circuit 12 operates the image memory 14, the image area designation circuit 20, and the interframe smoothing circuit 24 via the control bus 32. First, inter-frame smoothing is performed using the first frame and the second frame. The image area specifying circuit 20 is connected to the first area of the image memory 14.
A small area from which image data is to be read from the frame is specified, and the motion vector Mij of the small area is read from the motion vector memory 18 to determine the position of the small area in the first frame that corresponds to the small area in the first frame. A signal designating a small area of the first frame and a corresponding small area of a non-second frame is transmitted to the image memory 1 via the control bus 32.
4 is applied, and the image memory 14 outputs image data of each small area.

The inter-frame smoothing circuit 24 performs inter-frame smoothing using these image data, and stores the results in the image memory 1.
4 or a working frame (work frame other than the 1st to nth frames).

However, if the flag MF is set in the motion vector memory 18, the image data of the small area of the first frame is stored in the first frame or the working frame without performing the frame decimation.

The above processing is performed on the entire small area of the first frame in units of small areas, and then the image data of the first frame (or working frame) formed in this way and the kth (=3 to m ) frames, inter-frame smoothing is performed in the same way as above. Note that the image area specifying circuit 20 divides the small area of the k-th frame corresponding to the small area of the first frame (or working frame) into the first frame and the second frame.
k・Mi for the motion vector Mij between frames
It is estimated that it is at a position moved by j.

After completing the inter-frame smoothing up to the m-th frame in this manner, the control circuit 12 makes the image memory 14, the image area specifying circuit 20, the inter-frame smoothing circuit 24, and the motion vector memory 18 inactive.

Next, intra-frame smoothing processing is performed. The control circuit 12 operates the group determination circuit 22, the intra-frame smoothing circuit 26, the motion vector memory 18, and the image memory 14. The image memory 14 sends the image data of the small region of interest of the first frame (or working frame), which is the inter-frame smoothed frame, to the intra-frame smoothing circuit 26 . The group determination circuit 22 is connected to the motion vector memory 18.
The motion vectors of the small region of interest and the surrounding small regions are read from the subregion of interest, and surrounding small regions having motion vectors similar to the motion vector of the small region of interest are determined to be group 1, and small regions that are not similar are determined to be group 2. . The flag MF is also taken into consideration in determining this similarity. Specifically, flag MF
Group 1 is the small area where the is standing and the small area where it is not.
Judgment is made to ensure that they do not mix with each other.

Then, smoothing processing is performed within each of group 1 and group 2. In other words, by performing smoothing processing separately after dividing into Group 1 and Group 2, moving objects, for example, edge portions of areas belonging to Group 1, can be well preserved, and simple smoothing can Edge blurring can be prevented.

Further, in this embodiment, not only the above-mentioned operation but also the following operation can be performed. The group determination circuit 22 reads the image data of the small area belonging to group 1 from the image memory 14, calculates the feature amount of the group (in this case, a simple average value), and similarly reads the small area belonging to group 2, and calculates the feature amount of the group 2. Find the quantity. If the similarity of the features of these two groups is high, it is determined that intra-frame smoothing can be performed within the combined area of these two groups, and conversely, if the similarity is low, it is determined that intra-frame smoothing can be performed within the area of group l. It is determined that intra-frame smoothing can be performed. In-frame smoothing circuit 2
6 performs intra-frame smoothing based on this determination result, and stores the result in the working frame (frames other than the first frame) of the image memory 14. When the above processing is performed for all the small areas within the frame, the control circuit 12 puts the image memory 14, the group determination circuit 22, the motion vector memory 18, and the intraframe smoothing circuit 26 into a non-operating state.

Next, the control circuit 12 activates the image memory 14 and the interface circuit 30, and sequentially reads the intra-frame smoothed frame (working frame) image data from the image memory 14 and sends the image data to the interface circuit 30. The interface circuit 30 synchronizes with an external image output device (such as a printer) and outputs image data to the image output device. If the image output device is a printer, a still image is printed. Of course, if the human power of the image output device is an unlog signal, a D/A converter may be included in the interface circuit 30.

Input to the image memory 14, motion vector detection, inter-frame smoothing, intra-frame smoothing, and image output were performed by separate hardware, but of course, by a digital signal processing circuit with single or multiple program operations. It goes without saying that this can be achieved. To further increase the speed, the series of processes described above may be pipelined in units of small areas. This is also within the scope of the invention.

Although the processing order is inter-frame smoothing followed by intra-frame smoothing, it is also possible to perform intra-frame smoothing on each frame of the human image and then inter-frame smoothing. As a smoothing method, various filter processing such as weighted averaging can be used in addition to simple averaging.

In this embodiment, frameless smoothing is used as the second noise reduction means different from the first noise reduction means, but the present invention is not limited to this. Different smoothing may be performed.

[Effects of the Invention] As can be easily understood from the above explanation, according to the present invention, even for moving images, image blurring and false images (such as false contours and image duplications that do not originally exist) can be prevented. ) will not occur. Moreover, even if it occurs, it can be suppressed to such an extent that it cannot be visually recognized. Therefore, a clear still image with less noise can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a frame structure of the image memory 14, and FIG. 3 is an example of a moving image. 10, 30: Interface circuit 12: Control circuit
14: Image memory E6: Motion vector detection circuit 18
:Motion vector memory 20:Image area specification circuit 2
2: Group determination circuit 24: Inter-frame smoothing circuit
26: Intra-frame smoothing circuit 32: Control bus 34:
Image data bus 36: Vector data bus

Claims (1)

[Claims] a motion vector detection means for detecting a motion vector for each small region of a frame of interest of a moving image signal; and images of corresponding small regions of the frame of interest and a frame other than the frame of interest obtained by the motion vectors; A first noise reduction processing means that performs noise reduction processing in the time axis direction, and a second noise reduction processing means having a noise reduction characteristic different from that of the first noise reduction processing means. Video/still image conversion device.