KR101564974B1 - Method for image correction at ovelapped region of image, computer readable medium and executing device thereof - Google Patents

Abstract

The present invention relates to a method for correcting an image, and more particularly, to a method for correcting an image, comprising the steps of: identifying overlap regions between images projected from a plurality of projectors; And adjusting an element in which a difference in brightness or hue is generated.

Description

Field of the Invention [0001] The present invention relates to an image superimposing area correction method, a recording medium,

The present invention relates to an image processing method, and more particularly, to an image correction method and the like for correcting overlapping areas among images projected by a plurality of projectors to provide a uniform image as a whole.

Conventionally, a two-dimensional image is projected on a single screen disposed in front of an auditorium to reproduce images such as movies and advertisements in a theater. However, under such a system, the audience was forced to view only 2D (2D) images.

In recent years, 3D image technology has been developed that can provide stereoscopic images to the audience. 3D image technology is a technology that allows a user to feel stereoscopic effects in a plane image when different images are entered into the left eye and right eye of a person, The principle is to use two cameras equipped with different polarizing filters at the time of image capturing and to use glasses equipped with a polarizing filter at the time of viewing the images so that different images can be entered into the left eye and the right eye.

However, such a 3D technology can provide a stereoscopic image to a user, but still has a limitation in that the image itself is less immersive because it is merely viewing an image reproduced on a single screen. Also, there was a limitation that the direction of stereoscopic feeling that the audience perceives is limited to the direction in which a single screen exists. In addition, the conventional 3D technology is inconvenient to viewers because it is necessary to wear glasses or the like equipped with a polarizing filter at the time of watching the video, Sensitive audiences could feel dizziness or loudness.

Therefore, a so-called 'multi-screen screening system' which can solve the problems of the conventional screening system based on a single screen has been proposed (prior application of the present applicant). The 'multi-screen screening system' (A screen, a wall surface, and the like), and reproduces one unified image on a plurality of projected surfaces, thereby providing a three-dimensional feeling and an immersion feeling to the audience. In addition, the term "multi-screen movie theater" means an auditorium in which such a multi-screen screening system is built. 1 shows an example of a multi-screen display system.

In order to effectively operate the multi-screening system, techniques are required to effectively correct images projected on a plurality of projection surfaces. In the 'multiple screening system', a plurality of images projected on a plurality of projection planes other than a single projection plane must be integrally corrected, and the manner in which a plurality of images are corrected as the structure of an auditorium changes, Because the calibration process is very complex and the likelihood of errors is very high. Accordingly, there is a demand for technologies that can assist in the image correction process of such a multi-screen display system.

On the other hand, there is a case where an image is projected using not only a multi-screening system but also a plurality of projectors on a single projection surface. For example, the width of the projection surface is wide or the aspect ratio of the projection surface is not covered by one projector.

It is very important to provide a sense of unity when projecting an image using a plurality of projectors. Particularly, it is necessary to correct the image so that the boundary of the image projected from each projector or the overlap region and the non-overlap region are not distinguished.

Korean Patent Publication No. 2012-0020793

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide an image reproducing apparatus and method, in which images projected from respective projectors are reproduced in a unified sense as a whole when projecting images using a plurality of projectors.

In particular, the object of the present invention is to control the various elements of the image projected onto the image superimposing area to lower the degree of heterogeneity in the superimposing area and the non-superimposing area.

According to an aspect of the present invention, there is provided a method for correcting an image superposition area, the method comprising the steps of: identifying overlap regions between images projected from a plurality of projectors; determining a difference between at least one of brightness and color of the superimposed region and non- Judging and adjusting the elements in which the difference in brightness or color occurs.

Here, in the identifying step, an area in which the images are superimposed on the projection plane is calculated using the image projection area information of each projector stored or calculated in the master device controlling the plurality of projectors, and the coordinates of the area in which the images are superimposed, Or more.

According to an embodiment of the present invention, the determining step determines a brightness difference between the overlapping area and the non-overlapping area, and the adjusting step adjusts the brightness of the overlapping area or the non-overlapping area based on the brightest overlapping area. The brightness difference can be determined based on an image having R, G, and B values of a color equal to or less than a predetermined value.

According to an embodiment of the present invention, the determination step determines each frame of the image or each pixel of the image.

In an exemplary embodiment of the present invention, the adjustment step may include providing a result of the determination step to the user, and adjusting at least one of the brightness or hue of the image according to the adjustment command input from the user, The determining step calculates at least one of the brightness or color difference of the overlapping area and the non-overlapping area on a frame-by-frame basis. The adjusting step adjusts the brightness difference or the image difference Can be compensated.

In another embodiment of the present invention, the adjusting step may apply blur filtering at the boundary between the overlapping area and the non-overlapping area.

In an exemplary embodiment of the present invention, the adjustment step may reflect the transparency parameter on the image projected to the overlap area in each projector, and may reflect the chromatic aberration variable.

In one embodiment of the present invention, the method may further include a step of determining a color distortion due to the brightness adjustment after the adjustment step, and a step of re-adjusting the brightness of the overlap region or the non-overlap region according to the distortion.

The present invention also includes a computer-readable recording medium containing a program for executing the above-mentioned method for correcting an image overlapping area, and also includes an apparatus for executing a program for executing the program.

According to the present invention, when an image is projected using a plurality of projectors, it is possible to reproduce images with unity and unity as a whole. Especially, it is possible to control the various elements of the image projected onto the image superimposing area to reduce the sense of heterogeneity in the superimposing area and the non-superimposing area.

1 is a view showing an example of a structure of a multi-screen screening system.
2 is a flowchart showing an embodiment of the present invention.
3 is a flowchart showing another embodiment of the present invention.
4 is a flowchart showing another embodiment of the present invention.
5 is a diagram illustrating an example in which an image is projected by a plurality of projectors.
FIG. 6 is a diagram showing the brightness difference in the overlapping area and the non-overlapping area.
FIG. 7 is a diagram comparing images displayed on a projection surface before and after applying the embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

2 is a flowchart showing an embodiment of the present invention. The image overlap region correction method of the present invention includes the steps of: identifying overlap regions between images projected from a plurality of projectors; determining a difference between at least one of brightness or color of the overlapped region and non-overlap region of the image; And adjusting the element in which the difference occurs.

In order to identify overlapping areas between images, it is first necessary to check to which point of the projection surface the projected image is projected from each projector. To this end, in one embodiment of the present invention, a reference image formed with a predetermined pattern (e.g., a grid pattern) is projected for each projector, and it is determined at which point on the projection surface the reference image is projected. Then, by acquiring the coordinates of the overlapping point between the reference images projected from the respective projectors, it is possible to grasp which position on the projection plane is the overlapping area / non-overlapping area, and the overlapped area can be grasped have. In order to easily grasp the overlapping area, the reference image projected from the successive arranged projectors may have the same shape but different colors.

In another embodiment, the area in which the images are superimposed on the projection plane may be calculated using the image projection area information per projector stored or calculated in the master device controlling the plurality of projectors. The master device, which is an apparatus in which the method of correcting the image overlap region of the present invention is executed, may be pre-computed or stored in the image projection area information, which is information on which area of the projection surface each projector projects. Therefore, based on such information, it is possible to acquire the position, coordinates, and the like of the overlap area between the images projected from the plurality of projectors, and calculate how many overlapping (overlapping)

FIG. 6 is a diagram showing the brightness difference in the overlapping area and the non-overlapping area. 6A shows an example in which two projectors 1 and 2 project images, where a corresponds to the non-overlapping region and b corresponds to the overlapping region. The coordinates based on the projection plane of the overlapping area and the non-overlapping area can be obtained by the method described above or described later, or the coordinates based on the image projected at the position can be obtained.

6B shows an example in which four projectors 1 to 4 project images, where a is a non-overlapping area, b is an area in which images are superimposed by two projectors, c is an area in which four projectors And the area to be overlapped. The distinction between the non-overlap region and the overlap region is also important, but it is very important in implementing the present invention that the overlap region is overlapped by several projectors. This is because the degree of correction depends on the degree of overlapping of images. Referring to FIG. 6, the overlapped area is relatively bright compared to the non-overlapped area, but the colors are superimposed as the images are superimposed, and the light amount is increased as the images are superimposed. Embodiments of the present invention in consideration of these factors will be described later.

After the overlap area and the non-overlap area are identified, coordinates on the projection surface of each area, coordinates on the projector, and the like are obtained, the brightness or color difference between the overlapped area and the non-overlapping area of the image is determined.

In one embodiment of the present invention, the amount of light of an image projected at a specific time (a specific frame) during image reproduction is extracted for each pixel. This can be done by analyzing the image or by checking the amount of light for each area (overlapping area, non-overlapping area) of the entire image projected on the projection surface.

After determining the light amount difference at each pixel for each frame of the image, the brightness of the overlapping area or non-overlapping area is adjusted based on the brightest overlapping area.

The present invention is particularly applied when a dark image or a black image is projected.

In order to display black in the image, not only do you project no color on the projector (R, G, B value is 0), but also that no light is projected. However, since the projector needs to project color and light which change every moment by pixel, it can not completely block the light and color even when displaying black, and a minute amount of light is outputted.

Even if the amount of light output to the projection surface at the time of black representation is small, the environment in which the projector projects images is mostly dark (eg, theater auditorium). The human pupil is open, ie, It becomes a detectable state. When the brightness of light is added in the overlap region, the difference in brightness between the overlap region and the non-overlap region becomes a human perceptible level.

As described above, since the light emitted from the projector is inevitable in the dark (black) image projection and can not reduce the light amount, in one embodiment of the present invention, the brightness of the overlap region or non- . That is, the brightness of the other area is adjusted upward to match the brightest area.

In order to determine whether the currently projected image is a dark image, in the present invention, R, G, and B information of a specific pixel of a specific frame is obtained, and the obtained R, G, . As the R, G, and B values are closer to 0, the black color is represented. Thus, the dark regions of the image can be identified by analyzing R, G, and B values of each frame and each pixel.

In the present invention, the step of adjusting the difference between brightness or hue is performed in the following manner.

Referring to FIG. 3, information on the brightness difference between the overlapping area and the non-overlapping area, which is determined in the determination step, is provided to the user. The fundamental purpose of using the correction method of the present invention is to prevent overlapping regions and non-overlapping regions from being distinguished from human eyes. Accordingly, the brightness information is provided to the user through an interface which can be confirmed by the user, and at least one of brightness or color of the image is adjusted according to the adjustment command inputted from the user based on the brightness.

8 shows an example of a user interface for providing a determination result value to a user and receiving an adjustment command from a user according to the present embodiment. In the lower part of Fig. 8, the coordinates of the projection surface projected by the plurality of projectors, the superimposed / non-superimposing area, the brightness per pixel in each area, and the like are displayed. In the center, brightness, color information, So that the user can visually confirm it. The user can check the screen (user interface) and control the brightness or the like by adjusting the control command input means disposed on the right side. This makes it possible to correct the image in the image overlapping area.

When the above-mentioned control command is inputted, the adjusting step of the present invention adjusts the brightness of each pixel of the image by the following Equation (1).

[Equation 1]

R (x, y) = R 0 (x, y) + Offset (x, y)

G (x, y) = G 0 (x, y) + Offset (x, y)

B (x, y) = B 0 (x, y) + Offset (x, y)

(X, y) represents a specific position and coordinates of an image projected from the projector, and R ₀ (x, y) represents the R, G, B values Offset (x, y) is the color, brightness correction value and R (x, y) in (x, y) it means.

In the present invention, another embodiment of the step of adjusting the difference between the brightness or the color will be described with reference to FIG.

In this embodiment, the brightness or color difference in the overlapping area and the non-overlapping area is calculated for each frame and for each pixel in the frame. The brightness difference information or the color difference information extracts information (R, G, B) about the amount of light or color (R, G, B) of the projected image at each specific point in time (specific frame). When the color information and the light amount information extracted for each frame and for each pixel are calculated together with the coordinates of the overlapping area and the non-overlapping area, that is, color / light amount information of pixels belonging to the overlapping area and color / light amount information And the difference therebetween is calculated, it is possible to derive the image difference between the overlapping area and the non-overlapping area.

When the derived difference is added to the non-overlap region or the relatively dark overlap region, the image overlap region can be corrected.

In an embodiment of the present invention, by applying blur filtering in adjusting the brightness / hue, the brightness / hue is continuously changed at the boundary between the overlap region and the non-overlap region. As a result, An integrated image can be reproduced.

In an embodiment of the present invention, the adjustment step reflects the transparency variable alpha on the image projected into the overlapping area in each projector. This is to compensate for the distortion of the brightness and color of the image due to overlapping. For example, if a pixel in a superimposed image is projected three times by an image projected from three projectors, the color of the projector is added so that the image is reproduced at brightness three times brighter than the original one. In order to prevent this, the image projected from each projector can be projected by 1/3 of the original image, thereby displaying the image according to the original brightness. In this case, 1/3 is called a transparency variable (?). However, in the above example, setting the transparency variable to 1/3 is merely an example, and setting and applying the transparency variable is expressed by Equation (2) below.

&Quot; (2) "

C =? _I * C,? _I = 1

(C is the color ultimately expressed at each pixel, and alpha is the transparency variable at each pixel)

Turning to the above Equation (2) through a further example, i Assuming that the second projector and the j-th projector is superposed half by left / right, the projector i on the left side is reduced from the α _i value of 1 to 0 in the overlap region , The projector j located on the right side increases the value of alpha _j from 0 to 1 in the overlapping area. That is, the α value of each projector pixel is closer to 0 as it is closer to the boundary of the overlap region. If α _i + α _j = 1 is satisfied in the overlap region, color distortion due to image overlap can be corrected have.

In addition to the above embodiment, the present invention can further reflect the chromatic aberration variable in the transparency variable. The chromatic aberration variable is for correcting the chromatic aberration according to the above transparency variable.

As a result of experiments on correcting image distortion in the overlap region according to the previous embodiment, the image was correctly corrected in most regions, but a chromatic aberration occurred as the transparency parameter () approaches zero.

In order to solve such a problem, the present embodiment corrects the image by further reflecting the chromatic aberration variable on the transparency variable alpha. As the chromatic aberration variable, it is possible to set (1- alpha) so as to have a negative correlation with the transparency variable. However, this is merely an example, and various variables for recalibrating the chromatic aberration occurring when the transparency parameter is small can be set as the chromatic aberration variable.

In another embodiment of the present invention, the method may further include the step of determining the color distortion due to the brightness adjustment after the adjustment step and the step of adjusting the brightness of the overlap region or the non-overlap region according to the distortion. It is preferable that the present embodiment is applied when the brightness is adjusted in the dark portion or the black portion of the image that requires brightness adjustment as described above,

The brightness adjusted based on the dark image can distort the color rather than the bright image. Therefore, in the present embodiment, it is further possible to judge the color distortion due to the brightness adjustment and readjust the brightness of the overlap region or the non-overlap region according to the degree of distortion. The concrete method of judging the color distortion and adjusting the brightness and the like is the same as that described in the previous embodiment.

The present embodiment can be expressed by the following equation (3).

&Quot; (3) "

R (x, y) = R 0 (x, y) + Offset (x, y) * [(255- R 0 (x, y)) / 255] n

G (x, y) = G 0 (x, y) + Offset (x, y) * [(255- R 0 (x, y)) / 255] n

B (x, y) = B 0 (x, y) + Offset (x, y) * [(255- R 0 (x, y)) / 255] n

The RGB color display is determined from 0 to 255. The closer to 255, the lighter the color is to red / green / blue. Therefore, according to the above formula, the value of [(255 - R ₀ (x, y)) / 255] ⁿ becomes smaller as the color becomes lighter and the RGB value becomes larger. As a result, the value of Offset (x, y) becomes smaller and the degree of correction at the point (x, y) becomes smaller. As mentioned above, brightness is readjusted in the direction of reducing image distortion caused by brightness control.

n is an integer and can be selected as required, and it is confirmed that the image is recalibrated to an appropriate degree when the experimental result n is 20. [ However, this is merely an experimental example, and the present invention is not limited to the above formula (3) and the value of n.

5 is a diagram illustrating an example in which an image is projected by a plurality of projectors.

5 shows an example in which an image is projected by two projectors on one projection surface. The image on the left side by the projector 1 and the image on the right side by the projector 2 are displayed on the projection surface and the overlapping area of dotted lines in the middle corresponds to the overlapping area. In the example shown in Fig. 5, the images are reproduced in an integrated manner in the overlapping area and the non-overlapping area in a state in which the image overlapping area correcting method of the present invention described above is applied.

FIG. 7 is a diagram comparing images displayed on a projection surface before and after applying the embodiment of the present invention.

7 (a) is an image represented on the projection surface before correction, and it can be seen that the middle overlap region is brighter than the left and right non-overlap region. In the case of projecting an image using a plurality of projectors, the user feels a sense of heterogeneity in the image as shown in FIG. 7 (a). Therefore, when the embodiment of the present invention described above is applied, It becomes possible to reproduce.

The present invention may be embodied in the form of a program for executing a method of correcting an image overlap region according to the above-mentioned various embodiments, and includes a computer readable recording medium having such a program recorded thereon. Here, the recording medium does not simply mean a recording medium of a narrow meaning such as an HDD, a CD, and a magnetic disk, but should be viewed in a broad sense including a server having a storage, a computer, and the like.

In addition, the present invention includes an apparatus for executing such a program, and a projector control device, a computer, a server, and the like are considered to be included in the above-mentioned execution apparatus (master apparatus). In this case, the correction method of the present invention mentioned in the above embodiments can be implemented by a configuration for executing it, for example, a judgment / calculation is performed by a central processing unit (CPU) The user interface may be provided to a user through a display device or the like, and may receive a user command through an input device or the like.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. You should see.

Claims (14)

Identifying overlapping regions between images projected from a plurality of projectors;
Determining a difference between at least one of a brightness or a hue of the overlapping area and the non-overlapping area of the image; And
Adjusting an element in which a difference in brightness or color occurs;
Including the
Wherein the adjusting step further reflects a transparency parameter and a chromatic aberration variable having a negative correlation with the transparency parameter in an image projected to an overlapping area in each projector
2. The image processing apparatus according to claim 1, wherein the identifying step calculates an area in which images are superimposed on a projection surface using image projection area information of each projector stored or calculated in a master device controlling the plurality of projectors, Correction method
The method according to claim 1, wherein the identifying step calculates at least one of coordinates of an area in which an image is superimposed or degree of superimposition,
The method according to claim 1,
Wherein the determining step determines a brightness difference between the overlapping area and the non-overlapping area,
Wherein the adjusting step adjusts the brightness of the overlapping area or the non-overlapping area based on the brightest overlapping area.
The method according to claim 4, wherein the determining step determines a brightness difference based on an image having R, G, B values of a color less than a predetermined value
The method of claim 1, wherein the determining step comprises:
2. The method of claim 1, wherein the determining step comprises:
2. The method of claim 1,
Providing a result of the determination step to the user; And
Adjusting at least one of brightness or hue of an image according to an adjustment command input from a user;
A method of correcting an image overlapping area
The method according to claim 1, wherein the determining step comprises: calculating at least one of brightness or color difference of the overlapping area and the non-
Wherein the adjusting step corrects brightness difference or image difference to an image projected on a relatively dark area by using a result calculated for each frame,
The method of claim 1, wherein the adjusting step comprises applying blur filtering at a boundary between the overlapping area and the non-overlapping area.
delete A computer-readable recording medium having recorded thereon a program for executing a method of correcting an image overlapping area according to any one of claims 1 to 10
delete delete

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