KR20070042709A - A projector and a method of image revision - Google Patents

Abstract

The present invention relates to an image correction projector and an image correction method that enables the projector to be used without a separate screen.

The present invention provides a scaler unit for converting an input image signal into a display size, a display driver unit for converting the converted image signal into a signal format according to a type of panel, a camera unit for detecting a state of a projection surface of an image, and the camera. An image correction unit for correcting an image signal due to the state of the projection surface detected by the unit, a scaler unit, a driver unit, a camera unit, a micom unit for controlling the image correction unit, and a display panel for outputting the corrected image. It provides an image correction projector.

Therefore, according to the present invention, first, the projector can be used even on a general wall surface on which no white screen is installed, thereby overcoming the space limitation, and second, the distortion of the image due to the color or pattern of the projection surface can be corrected.

Projector, Image Correction

Description

Image correction Projector and image correction method

1 is a block diagram of a conventional projector

2 is a block diagram of an image correction projector according to the present invention.

3 is a block diagram of an image correction unit of an image correction projector according to the present invention.

4 is a flowchart of an image correction method according to the present invention.

5 is an embodiment of an image correction projector according to the present invention.

6 is a diagram for acquiring position information of a screen in an image correction method according to the present invention;

* Explanation of symbols for main parts of drawings *

10 scaler unit 20 display driver unit

30: micom part 40: display panel

50: image correction unit 60: camera unit

51: internal pattern generator 52: memory

53: controller 54: image correction block

The present invention relates to a projector, and more particularly, when a projector screen is projected on a wall surface in which a pattern is formed with a non-saturated color rather than a screen, a distortion of an image caused by the pattern or color influence of a wallpaper other than white. The present invention relates to a projector and an image correction method for correcting a screen after obtaining information on a wallpaper pattern using a camera before projecting an image to eliminate color temperature changes.

1 shows a block diagram of a conventional projector. The conventional projector is composed of a scaler 10, a display driver 20, a microcomputer 30, and a display panel 40. Therefore, the conventional projector cannot be reversely corrected for the image, so that the projector can be used only with a white screen.

In order to overcome the above problems, there is a technology for controlling white contrast and brightness contrast of a screen by sensing ambient light.

However, this method is limited because it does not detect the screen that finally enters the human eye. For example, the optical characteristics of the projection surface to be projected on the projector's screen cannot be detected, and it is impossible to correct pixel by pixel for factors that partially affect the screen without uniformly affecting the screen such as uniformity. There is.

The present invention is to solve the above problems, an object of the present invention is to provide a projector that can be used without distortion of the image even when projecting the image on a normal wall without having a separate white screen.

Another object of the present invention is to provide a method of reversing the image of a projector by acquiring information of a projection surface.

In order to achieve the above object, the present invention provides a scaler unit for converting an input image signal into a display size, a display driver unit for converting the converted image signal into a signal format according to the type of panel, and a state of the projection surface of the image. A camera unit for sensing, an image correction unit for correcting an image signal due to the state of the projection surface detected by the camera unit, a micom unit for controlling the scaler unit, a driver unit, a camera unit, an image correction unit, and the corrected image It provides an image correction projector including the output display panel.

The image correction unit may be obtained by a pattern generator for generating a test image for obtaining state information of a projection surface, an image adjusting block for correcting an actual image based on the obtained information, and a test image of the camera unit and the pattern generator. A memory for storing the adjusted information and the adjusted image, and a controller for controlling each block of the image correction unit provides an image correction projector.

The camera unit provides an image correction projector, which detects an external projection surface and transfers the sensed image to the image correction unit.

The pattern generator provides an image correction projector, characterized in that for generating a test image for obtaining at least one or more of the position information of the projection surface of the projector, the shooting position information of the camera unit, or the pattern information of the projection surface.

The image adjusting block determines a reference brightness for each R.G.B and provides an image correction projector, characterized in that to adjust the image to correspond to the reference brightness.

The reference brightness provides an image correction projector, wherein the minimum brightness becomes a reference brightness when the brightness of each pixel of the image is equal to or greater than a threshold brightness.

In addition, the reference brightness provides an image correction projector, characterized in that the threshold brightness becomes the reference brightness when there is a brightness equal to or less than a threshold brightness among the brightness for each pixel of the image.

The image correction unit provides an image correction projector, characterized in that to correct an image in real time with respect to a real-time input image.

The present invention provides a method of matching an optical characteristic of a projector with a characteristic of a camera, acquiring position information of a screen, acquiring information of a projection surface of a projector with a camera, and image of the projector based on the obtained projection surface information. It provides an image correction method comprising the step of correcting.

The acquiring position information of the screen may include generating a black test image on a projection surface, generating a white test image on a corner portion of the projection surface, capturing the projection surface on which the test image is generated, And converting the captured image into a binary image of 0 and 1 to obtain position coordinates of the corner.

Acquiring the information of the projection surface of the projector with the camera, generating a full white test image on the projection surface, acquiring an initial image including the full white test image, position information of the acquired screen and full white And obtaining brightness of the projection surface based on the initial image information including the test image.

Correcting the image of the projector based on the obtained projection surface information may include determining the threshold brightness on the screen for each egg (R), paper (G), ratio (B), and comparing the brightness in the image to determine the egg (R). ), G (G), the ratio (B) provides a method for correcting the image, characterized in that the correction by reference brightness.

Compare the on-screen threshold brightness by the egg (R), paper (G), and rain (B) and the brightness in the image.If the brightness in the image is all brighter than the threshold brightness on the screen, the image is matched to the darkest of the brightness in the image. It provides an image correction method characterized in that to correct the image of the projector.

Compare the threshold brightness on the screen for each egg (R), finger (G), and rain (B) with the brightness in the image, and if there is an image that is darker than the threshold brightness on the screen, G), an image correction method for correcting an image of a projector according to a threshold brightness on a screen for each ratio (B) is provided.

Correcting the image of the projector based on the obtained projection surface information provides an image correction method, characterized in that for correcting an image in real time with respect to an image input in real time.

Therefore, according to the present invention, first, the projector can be used even on a general wall surface on which no white screen is installed, thereby overcoming the space limitation, and second, the distortion of the image due to the color or pattern of the projection surface can be corrected.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described.

2 is a block diagram of a circuit unit of an image correction projector according to the present invention. The image correction projector according to the present invention includes a scaler unit 10 for converting an input image signal into a display size, and a display driver unit 20 for converting the converted image signal into a signal format according to the type of panel. It further comprises a camera unit 60 for detecting the state of the projection surface of the image correction unit 50 for correcting the image signal due to the state of the projection surface detected by the camera unit. The scaler unit 10, the driver unit 20, the camera unit 60, the microcomputer unit 30 for controlling the image correction unit 50, and a display panel unit 40 for outputting the corrected image. .

Basically, the display panel has a fixed image resolution, whereas the input signal comes in various image formats. At this time, the block which changes the size of the input signal to match the image resolution of the panel is a scale block. In addition, there are various types of display panels such as LCD, DLP, LCOS, etc. In order to display an image on the panel, it is necessary to convert the video signal into a unique signal format suitable for the panel. This part is handled by the display driver block. There is a need for a microcomputer block to control the scaler and the display driver.

The camera unit 60 is a detection unit for detecting a state of a projection surface on which an image is to be screened, and is used to correct an image of a projector in real time according to a practical external environment.

The image correcting unit 50 is a block for correcting an image of the projector based on the information of the projection surface obtained by the camera unit 60.

The image correction unit 50 includes a pattern generator 51 for generating a test image for obtaining state information of a projection surface, an image adjustment block 52 for correcting an actual image based on the obtained information, and the camera unit. The memory 53 stores information obtained by the test image of the pattern generator and the adjusted image, and a controller 54 that controls each block of the image corrector.

The pattern generator 51 generates a test image for determining the screen position of the projection surface, generates a test image for determining the screen position of the camera unit, and generates a test image for determining the pattern information of the projection surface. Generate.

The memory 53 is a block that stores information obtained based on a test image generated by a pattern generator and information about a projection surface obtained by photographing the camera unit.

The image adjustment block 52 is a block for correcting an actual input signal based on the information obtained by the pattern generator 51 and the information obtained by the camera unit 60.

The controller 54 is a block that controls the entire configuration block of the image correction unit 50.

5 illustrates the image correction method according to the present invention in order. 6 illustrates a method of obtaining location information of a screen.

Referring to FIG. 5, the method of correcting an image according to the present invention comprises: matching optical characteristics of a projector with characteristics of a camera, acquiring position information of a screen, acquiring information of a projection surface of the projector by a camera, and acquiring Correcting the image of the projector due to the information of the projected surface.

If the user presses the wallpaper correction button or activates the wallpaper correction function via OSD operation while the wallpaper correction function is turned off, the controller first obtains screen position information for matching the projector screen with the camera screen. Do it. After that, the color reflectance information of each pixel of the wall on which the screen is projected is obtained. Next, the image is corrected and output using the correction factor value for each pixel to remove the pattern of the wallpaper on the screen using the dichroic reflectance information. If the user toggles the wallpaper correction function again, the correction function is turned off.

The step of matching the optical characteristics of the projector and the characteristics of the camera is set to a condition in which the full white pattern input is the brightest in the projector, and then adjusted so that the maximum output is obtained in a range where the camera output is not saturated at this time. The brightest conditions result in maximum projector brightness and contrast adjustments, minimum throw distance, and minimal optical zoom.

The step of acquiring the position information of the screen actually differs between the portion to be photographed in order to obtain information on the surface on which the image is projected and the surface on which the camera is projected, and thus, it is necessary to acquire the information and to match them. .

6 is an embodiment of a method of obtaining screen position information. After outputting a test image with white pixels in the order of four corners of 0, 1, 2, and 3 on the entire black screen as a projector input (FIG. 6A), and then capturing these screens through the camera in turn (FIG. 6B). , Convert to binary image of 0 and 1, get the coordinates of the value 1 and get the position of the four corners of the screen (x ′ ₀ , y ′ ₀ ), (x ′ ₁ , y ′ ₁ ), (x ′ ₂ , y ′ ₂ ) and (x ′ ₃ , y ′ ₃ ) as position coordinates.

Meanwhile, (x ′, y ′) is the position coordinates of the four corners of the screen (x ′ ₀ , y ′ ₀ ), (x ′ ₁ , y ′ ₁ ), (x ′ ₂ , y ′ ₂ ), (x ′ ₃ , y ′ ₃ ) and the coordinates (x, y) on the projector screen for which brightness is desired are calculated by the following equation (Equation 1).

In the present specification, the lowercase and uppercase letters of the English variables used in the mathematical expressions are used in the same meaning, and the lowercase and uppercase letters are used for the sake of typographical problems.

X′=

X ′ =

Y ′ =

In this case, Xres means horizontal resolution-1 of the projector screen, and Yres means vertical resolution-1 of the projector screen. For example, for XGA panels, Xres = 1023 and Yres = 767.

Acquiring information of the projection surface of the projector by the camera first outputs a full white test image on the screen from an internal pattern generator. The camera then acquires the initial image that the full white projector screen contains.

In this case, when the coordinate on the projector screen is (x, y) and the position coordinate on the camera is (x ′, y ′), the position coordinates of the four corners of the previously acquired screen (x ′ ₀ , y ′ ₀ ), For (x ′ ₁ , y ′ ₁ ), (x ′ ₂ , y ′ ₂ ), (x ′ ₃ , y ′ ₃ ), the brightness of R, G, B at the coordinates (x, y) on the projector screen Bw (x, y, c) is obtained from the R, G, B images Bc (x ', y', c) from the camera image pickup device by the following equation (Equation 2).

Bw (x, y, c) = a (c) x '+ b (c) y' + c (c) x'y '+ d (c)

At this time, the range of x, y, x ', y' and c satisfy the following.

0≤x≤ horizontal resolution of the projector-1

0 ≤ y ≤ vertical resolution of the projector-1

0≤x'≤Horizontal resolution of camera imaging element-1

0≤y′≤Vertical resolution of camera imaging device-1

c = r or g or b (red, green, blue)

At this time, a (c), b (c), c (c), d (c) is the same as the following equation (Equation 3).

c (c) = Bc ([x ′], [y ′]) + Bc ([x ′] + 1, [y ′] + 1) -Bc ([x ′] + 1, [y ′])

-Bc ([x ′], [y ′] + 1)

a (c) = Bc ([x ′] + 1, [y ′])-Bc ([x ′], [y ′])-c (c) [y ′]

b (c) = Bc ([x ′] + 1, [y ′])-Bc ([x ′], [y ′])-c (c) [x ′]

d (c) = Bc ([x ′], [y ′])-a (c) [x ′]-b (c) [y ′]-c (c) [x ′] [y ′]

At this time, [x '] is the maximum integer not exceeding x', [y '] means the maximum integer not exceeding y'.

Correcting the image of the projector based on the obtained projection surface information calculates and stores the pattern correction coefficient for each pixel by using the captured image, thereby correcting the image of the projector.

The principle of pattern correction is that the input signal itself is uniformly manipulated at the lowest reflectance value in which the reflectances of R, G, and B are different according to the wallpaper pattern with respect to the full white input. In this case, the screen is dark in general, so if there is an excessively dark color on the pattern, the screen may be dark if the input signal is corrected to this color. Therefore, the target brightness Btarget (c) for each R, G, and B should be determined before the pattern is corrected.

First, the coordinates and colors (Xmin, Ymin, Cmin) of the minimum brightness considering the R, G, B adjustment value Cadj (c) from the image obtained through the camera are obtained by the following equation (Equation 4).

(Xmin, Ymin, Cmin)는 값이 최소인 (x,y,c)

(Xmin, Ymin, Cmin) is the smallest value (x, y, c)

At this time, all x and y ranges, and c values satisfy the following.

0 ≤ X ≤ Xres, 0 ≤ Y ≤ Yres (X, Y integer)

c = r or g or b

Comparing the minimum brightness at this time with the allowable threshold brightness Bth of the target brightness, the target brightness Btarget can be obtained.

The reason why we compare it with the allowable threshold value Bth is to prevent the projector screen from being too dark overall when the saturation of the wallpaper pattern or the brightness of the pattern is very dark.

The target brightness (Btarget) for each of R, G, and B, and the pattern correction coefficient C (x, y, c) for each of R, G, and B are described in the following equation (Equation 5).

Btarget = Max (Bw (XminYminCmin), Bth)

The pattern correction coefficient is used to correct the input image in real time. At this time, the R, G, B outputs of the R, G, and B inputs Rin (x, y), Gin (x, y), and Bin (x, y) for each pixel are represented by Equation (6) and same.

Rc (x, y) = C (x, y, r) Rin (x, y),

Gc (x, y) = C (x, y, g) Gin (x, y),

Rc (x, y) = C (x, y, b) Rin (x, y)

The present invention is not limited to the above-described embodiments, and can be modified by those skilled in the art as can be seen from the appended claims, and such modifications are within the scope of the present invention. .

The effects of the image correction projector and the image correction method according to the present invention described above are as follows.

First, the projector can be used even on a common wall without a white screen, thereby overcoming space limitations.

Second, the distortion of the image due to the color or pattern of the projection surface can be corrected.

Claims (15)

A scaler unit for converting an input video signal into a display size; A display driver unit converting the converted video signal into a signal format according to a type of panel; A camera unit for detecting a state of a projection surface of an image; An image correction unit for correcting an image signal due to the state of the projection surface detected by the camera unit; A microcomputer unit for controlling the scaler unit, the driver unit, the camera unit, and the image correction unit; And a display panel for outputting the corrected image. The method of claim 1, wherein the image correction unit, A pattern generator for generating a test image for obtaining state information of the projection surface; An image adjustment block to correct an actual image based on the obtained information; A memory for storing information obtained by the test image of the camera unit and the pattern generator and the adjusted image; And a controller for controlling each block of the image correction unit. The method of claim 1, And the camera unit detects an external projection surface and transfers the sensed image to the image correction unit. The method of claim 2, And the pattern generator generates a test image for acquiring at least one or more of the position information of the projection surface of the projector, the photographing position information of the camera unit, and the pattern information of the projection surface. The method of claim 2, And the image adjustment block determines a reference brightness for each R.G.B and adjusts the image to correspond to the reference brightness. The method of claim 5, wherein the reference brightness, And the brightness of each pixel of the image is greater than or equal to a threshold brightness, wherein the minimum brightness becomes a reference brightness. The method of claim 5, wherein the reference brightness, And a threshold brightness becomes a reference brightness when the brightness of each pixel of the image is less than or equal to a threshold brightness. The method of claim 1, And the image correcting unit corrects an image in real time with respect to a real-time input image. Matching the optical characteristics of the projector with the characteristics of the camera; Obtaining location information of a screen; Acquiring information of the projection surface of the projector with a camera; Correcting an image of the projector based on the obtained projection surface information. The method of claim 9, wherein the obtaining of the position information of the screen comprises: Generating a black test image on the projection surface; Generating a white test image at a corner of the projection surface; Capturing a projection surface on which the test image is generated; And converting the captured image into binary images of 0 and 1 to obtain position coordinates of the corners. 10. The method of claim 9, wherein acquiring information of the projection surface of the projector by the camera, Generating a full white test image on the projection surface; Obtaining an initial image including a full white test image; And obtaining brightness of the projection surface based on the acquired position information of the screen and initial image information including the entire white test image. The method of claim 9, wherein the correcting the image of the projector based on the obtained projection surface information comprises: It sets the threshold brightness on the screen for each egg (R), paper (G), and rain (B), and compares the brightness in the image to compensate for the reference brightness for each egg (R), paper (G) and rain (B). Image correction method. The method of claim 12, Compare the on-screen threshold brightness by the egg (R), paper (G), and rain (B) and the brightness in the image.If the brightness in the image is all brighter than the threshold brightness on the screen, the image is matched to the darkest of the brightness in the image. Image correction method characterized in that for correcting the image of the projector. The method of claim 12, Compare the threshold brightness on the screen by the egg (R), edge (G), and rain (B) with the brightness within the image.If there is an image darker than the threshold brightness on the screen, And (G) and (B) correcting the image of the projector according to the threshold brightness on the screen. The method of claim 9, And correcting the image of the projector based on the obtained projection surface information, correcting the image in real time with respect to the image input in real time.

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