KR100734847B1 - Apparatus and method for taking a clear image in slow shutter speed - Google Patents

Abstract

The present invention relates to a method and apparatus for obtaining a clear image at a slow shutter speed when photographing a digital camera, comprising: an image acquisition unit for sequentially receiving and managing n image frames while a lens is open; A motion detector configured to set the first image taken as the reference frame as soon as the lens is opened, and to sequentially detect a motion degree of each of the second to nth image frames with respect to the reference frame based on a block matching algorithm; An image corrector configured to correct an image by comparing a reference frame region with an image frame region in which a motion within a threshold is detected when the detected movement degree is within a preset threshold; and a combination of the reference frame and the image frames corrected by the image corrector. And an image generator for generating a final frame.

Shutter speed, shake

Description

Apparatus and method for taking a clear image in slow shutter speed}

1 is a block diagram illustrating an internal configuration of an apparatus for detecting a clear image at a slow shutter speed as a preferred embodiment of the present invention.

FIG. 2 shows one embodiment of an apparatus for detecting a clear image at the slow shutter speed shown in FIG. 1.

3 illustrates an embodiment of correcting an image in the image corrector according to the present invention.

4 shows a conceptual diagram of a block matching algorithm.

5 shows a flowchart for correcting and generating an image to detect a clear image at a slow shutter speed.

The present invention relates to a method and apparatus for easily obtaining a clear image by anyone using a digital camera in an environment requiring a slow shutter speed such as running water or night scene photography even without a tripod.

Recently, with the spread of low-end digital cameras and mobile phones equipped with cameras, it has become an era where anyone can easily take pictures and immediately check the recorded images. Only recently, the manual functions used only by high-priced digital cameras were used only by professionals. Multifunctional digital cameras that can be easily operated by the general public by utilizing this low-cost camera are widely used and used.

In the conventional method, the image is prevented from being blurred by a momentary hand shake phenomenon. By using the characteristics of the movement occurring at the instant time, only the moving component between the current frame and the previous frame is analyzed to ignore the current frame. Is commonly used, or many similar methods have been proposed.

However, if the shutter speed is increased, at least two to several tens of frames or more must be processed, and it is difficult to solve a method of ignoring any frame. In addition, when shooting with a slow shutter speed when shooting with a digital camera, there is a problem that it is difficult to obtain a clear and cool image by focusing on one place without moving the camera for a long time.

In order to solve the above problems, the present invention is to detect a clear image of the user desired form by estimating the movement of the camera centered on the focus initially set by the user and correcting the image position as much as the movement even at a slow shutter speed. do.

In a preferred embodiment of the present invention, a clear image detection apparatus at a slow shutter speed, the image acquisition unit for sequentially receiving and managing n image frames while the lens is open; A motion detector configured to set an image first captured when the lens is opened as a reference frame, and sequentially detect a motion degree of each of the second to nth image frames with respect to the reference frame based on a block matching algorithm; When the detected degree of motion is within a predetermined threshold, the pixel frame that is outside the reference frame area of the image frame area is deleted by comparing the reference frame area with the image frame area where the motion within the threshold is detected, and the image is deleted. An image correction unit for moving a pixel area within the reference frame area of the frame area to correspond to a corresponding pixel area of the reference frame area, and replacing the deleted pixel area with a corresponding pixel area of the reference frame area; and And an image generator for generating a final frame by combining the reference frame and the image frames corrected by the image corrector.

In another preferred embodiment of the present invention, a clear image detection method at a slow shutter speed includes the steps of: (a) sequentially receiving and managing n image frames while the lens is open; (b) setting the first image taken as the reference frame when the lens is opened; (c) detecting a degree of motion based on a block matching algorithm in the input order of the reference frame and the second to nth image frames sequentially stored in the step (a); (d) When the degree of motion detected in step (c) is within the threshold, the reference frame area is compared with the image frame area where the motion within the threshold is detected, and the reference frame area is removed from the image frame area. The pixel area is deleted, and a pixel area within the reference frame area of the image frame area moves to correspond to a corresponding pixel area of the reference frame area, and the deleted pixel area corresponds to a corresponding pixel area of the reference frame area. A correction step of replacing with; And (e) generating a final frame by combining the reference frame and the image frames corrected in the step (d).

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the same elements among the drawings are denoted by the same reference numerals and symbols as much as possible even though they are shown in different drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a block diagram illustrating an internal configuration of an apparatus for detecting a clear image at a slow shutter speed as a preferred embodiment of the present invention.

It is assumed that an apparatus for detecting a clear image at a slow shutter speed of the present invention is used in an apparatus capable of adjusting shutter time and aperture.

The clear image detection apparatus includes an image acquisition unit 120, a motion detection unit 130, an image correction unit 140, and an image generation unit 140.

The image acquisition unit 120 converts the light coming through the lens 110 into an electronic signal while the shutter is open, and stores, manages, and processes n image frames in the input order in the camera memory.

Thereafter, the motion detector 130 sets the first image taken as the reference frame as soon as the lens is opened, and adjusts the degree of motion in the order of inputting each of the second to nth image frames with respect to the reference frame based on a block matching algorithm. Detect sequentially.

The image corrector 140 discards the image frame exceeding the threshold when the motion degree of each of the second to nth image frames detected by the motion detector 130 exceeds a preset threshold. The image frame within the threshold corrects the image data by comparing the reference frame region with the image frame region.

The image generator 140 generates a final frame by combining the reference frame and the image frames corrected by the image corrector 140 and then displays the final frame through the LCD.

FIG. 2 shows one embodiment of an apparatus for detecting a clear image at the slow shutter speed shown in FIG. 1.

The image capturing unit 120 converts the incoming light into an electronic signal for a period of time after the lens is opened by pressing the camera shutter and the moment the lens is closed, and is sequentially stored in the frame order management device 210. At this time, the frame entering the image acquisition unit 120 may enter from at least two frames to several tens of frames according to the shutter speed.

The motion detector 130 sets the first image that is input as the lens is opened as the reference frame is stored as the reference frame is stored as soon as the user first takes a desired angle of view and presses the shutter.

After that, each of the incoming signals is a second video frame. 3rd video frame ... The nth video frame is controlled by the frame order management device 210, and is sequentially transmitted to the next frame storage device 230 to compare each video frame with a reference frame.

Then, the motion detector 130 compares each of the reference frame and the second image frame, then the reference frame and the third image frame, the reference frame and the nth image frame, respectively, based on the block matching algorithm. The motion degree of each of the first image frame is sequentially detected.

The block matching algorithm used in the present invention divides the current frame into several smaller blocks (hereinafter, referred to as reference blocks) having a size of N × M, and then divides each reference block into a predetermined region (the reference block is divided into up, down, left, and right sides of the previous frame). Compared to several blocks in an area shifted by + (p-1) pixels in p, hereinafter referred to as a search area, the most similar block (hereinafter referred to as a matching block) is found, and the relative of the matching block with respect to the reference block The technique of setting the position as a motion vector. This motion estimation reduces the data to be transmitted by maximizing the correlation between the two frames (see FIG. 4).

Thereafter, in the case of a frame with motion detected by the motion detector 130, the frame is temporarily stored in the temporary frame storage device 240 to correct an image.

The final frame storage device 250 corrects the image frames stored in the temporary frame storage device 240 based on the reference frame, and then generates and stores the final frame by combining the corrected images with the reference frame.

Thereafter, the final frame stored in the final frame storage device 250 is displayed on the user's camera LCD through the frame interface.

3 illustrates an embodiment of correcting an image in the image corrector according to the present invention.

A reference frame (P) 310 and an image frame (P + n) 320 of the nth input signal after the reference frame are shown in S350. A critical region (B) 330 is shown in which the movement of the reference frame (P) 310 can be allowed in S350.

The motion detector 130 detects the moved position of the image frame P + n frame of the nth input signal based on the reference frame P 310 by using a block matching algorithm. In the use of the block matching algorithm, the reference block and the size of the block may be set to an appropriate size according to the search environment at the C position which is the center of the reference frame. At this time, if the color of the pixel of the center region is almost no change, it is possible to determine a block for motion detection at a suitable distance along the diagonal in both directions from the center point C.

The motion detector 130 detects that the reference frame P 310 has moved by (Dx, Dy) using a block matching algorithm. At this time, when the movement of the P + n image frame is so large that it leaves the threshold search area B 330, the probability of detecting the movement with respect to the corresponding image frame is low. Therefore, when the movement of the P + n image frame is so large that it leaves the threshold search area B 330, the corresponding image frame is deleted.

As a result of comparing the reference frame P 310 and the P + n image frame 320, the common area 350 exists (S360). Since the common area differs only in position but is actually a valid image desired by the user, the image correction unit 140 is used to generate the final frame through correction.

The image corrector 140 compares the P + n image frame 320 with the reference frame P 310 and then deletes the region 340 outside the region of the reference frame P 310 except for the common area 350. (S360). Thereafter, only the position of the detected common area 350 is corrected by (-Dx, -Dy) (S370).

In this case, since the corrected P + n image frame 320 has a smaller area than the reference frame P due to the deleted region 340, the remaining space 360 retains the data of the reference frame P 310, which is the original pixel. The copy and replace the deleted area (S380).

The image corrector 140 deletes the image frames that deviate from the predetermined threshold region for each of the image frames whose motion is detected by the motion detector 130 from the reference frame and the second image frame to the nth image frame. The other image frame corrects the image frames through the technical concept as in the embodiment shown in FIG.

4 shows a conceptual diagram of a block matching algorithm.

5 shows a flowchart for correcting and generating an image to detect a clear image at a slow shutter speed.

The motion detection unit detects whether there is motion (S510), and if the motion is not detected, processes the next video frame (S511), and if it detects the motion, it is determined whether it is within a critical area (S520).

If out of the critical region, the frame is deleted and the process for the frame is terminated (S521). If not within the threshold region, a motion is detected among the reference frame and the nth image frame from the nth image frame, but a common region is detected for each of the image frames within the threshold region (S530), and then moved as much as the movement occurs. Temporarily stored in the temporary frame T (S540). The empty area of the temporary frame T is replaced with data of a corresponding area in the reference frame (S550).

Thereafter, the corrected image frames are combined with the reference frame. At this time, the image data input for the given shutter time is input, and the difference between the reference frame and the newly input frame is continuously corrected, but the ε value can be added or subtracted as a factor for adjusting the brightness difference according to the situation (S560).

For example, when shooting a long time, such as night scene shooting, since the P 'value may exceed a certain value, it is possible to maintain the appropriate brightness by adjusting the ε value.

P '(x, y) = P' (x, y) + | P (x, y) -T (x, y) | ± ε (S560) indicates that the final frame P '(x, y) is equal to the current frame. The equation is generated by continuously updating the corrected difference of the temporary frame in the reference frame. The difference between the reference frame and the newly input frame is continuously corrected using ε, and the brightness difference is adjusted according to the situation. After that, when the shooting ends after the shutter time, the entire process is finished by outputting the image stored in the final frame through the LCD.

The invention can also be embodied as computer readable code on a computer readable recording medium. Computer-readable recording media include all types of recording devices that store data that can be read by a computer system.

Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, which are also implemented in the form of carrier waves (for example, transmission over the Internet). It also includes. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims.

Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Even when shooting is difficult due to the lack of a tripod during the slow shutter time, it is possible to obtain a clear image without shaking through various current digital cameras in which the manual function is common through the present invention.

As an added benefit, current digital camera users prefer small, compact cameras, but it is difficult to carry extra-complicated additional equipment such as tripods. You can expect

Claims (2)

An image acquisition unit configured to sequentially receive and manage n image frames while the lens is open; A motion detector configured to set an image first captured when the lens is opened as a reference frame, and sequentially detect a motion degree of each of the second to nth image frames with respect to the reference frame based on a block matching algorithm; When the detected degree of motion is within a predetermined threshold, the pixel frame that is outside the reference frame area of the image frame area is deleted by comparing the reference frame area with the image frame area where the motion within the threshold is detected, and the image is deleted. An image correction unit for moving a pixel area within the reference frame area of the frame area to correspond to a corresponding pixel area of the reference frame area, and replacing the deleted pixel area with a corresponding pixel area of the reference frame area; and And an image generator for generating a final frame by combining the reference frame and the image frames corrected by the image corrector. (a) sequentially receiving and managing n image frames while the lens is open; (b) setting the first image taken as the reference frame when the lens is opened; (c) detecting a movement degree of each of the second to nth image frames sequentially stored in the reference frame and the step (a) based on a block matching algorithm; (d) When the degree of motion detected in step (c) is within a predetermined threshold, the pixel outside the reference frame area of the image frame area is compared by comparing the reference frame area with an image frame area where motion within the threshold is detected. An area is deleted, and pixel areas within the reference frame area of the image frame area are moved to correspond to corresponding pixel areas of the reference frame area, and the deleted pixel area is a corresponding pixel area of the reference frame area. Replacing correction step; And and (e) generating a final frame by combining the reference frame and the image frames corrected in the step (d).

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