JP5141259B2 - projector - Google Patents

Description

  The present invention relates to a projector.

When projecting an image with a projector, there may be a case where there is a pattern or reflectance unevenness on the projection surface, a lighting unevenness on the projector, or an influence of the surrounding illumination environment on the projected image. In such a case, the projection image is not accurately displayed because the pattern or unevenness of the projection surface overlaps the projection image. In order to offset the influence of the pattern and display the projection image accurately, the projection plane on which the predetermined projection image is projected is photographed, and the maximum of the minimum luminance of each pixel in the projection plane of the photographed image is taken. Japanese Patent Application Laid-Open No. 2004-151820 discloses a technique for correcting a projected image so that the dynamic range of the projected image falls between the value and the minimum value of the maximum luminance of each pixel.
JP 2004-158941 A

  However, if there is a part of the projection surface that is very dark (low brightness) or high in saturation, the dynamic range of the entire projected image will be corrected extremely narrowly due to the influence of that part. There is a problem that it becomes worse.

(1) A projector according to a first aspect of the present invention includes a correction unit that corrects a projection image using a captured image obtained by shooting a projection surface on which a predetermined projection image is projected, and a projection that is corrected by the correction unit. Projection means for projecting an image, detection means for detecting a portion where the brightness of the projection surface is dark or a portion with high saturation on the projection surface, and a portion where the brightness of the detected projection surface is dark or projection based on the captured image Informing means for informing the user of the high-saturation portion of the surface is provided.
(2) According to a second aspect of the present invention, there is provided a projector that corrects a projection image using a captured image obtained by photographing a projection surface on which a predetermined projection image is projected, and a projection corrected by the correction unit. Projection means for projecting an image, detection means for detecting a portion where the brightness of the projection surface is dark or a portion with high saturation on the projection surface, and a portion where the brightness of the detected projection surface is dark or projection based on the captured image Control means for controlling the size of the projection image projected onto the projection surface so that the projection image is not superimposed on the high-saturation portion of the surface.
(3) According to a third aspect of the present invention, there is provided a projector according to a third aspect of the present invention, a correction means for correcting a projection image using a photographed image obtained by photographing a projection surface on which a predetermined projection image is projected, and a projection corrected by the correction means. Projection means for projecting an image, detection means for detecting a portion where the brightness of the projection surface is dark or a portion with high saturation on the projection surface, and a portion where the brightness of the detected projection surface is dark or projection based on the captured image Control means for controlling the projection position and size of the projection image projected onto the projection surface so that the projection image is not superimposed on the highly saturated portion of the surface.
(4) A fourth aspect of the invention is the projector according to the second or third aspect, wherein the brightness of the projected surface detected by the control means is low even if the size of the projected image is smaller than a predetermined size, Or a notification means for notifying a user of a detected dark portion of the projected surface or a highly saturated portion of the projected surface when a projected image to be projected onto the projected surface is superimposed on a highly saturated portion of the projected surface It is characterized by providing.
(5) The invention of claim 5 comprises an input means for the user to input that the dark part or the highly saturated part has been removed from the projection surface in the projector according to claim 1 or 4, and the correction means When the input means inputs that the dark part or high-saturation part has been removed from the projection surface, a photographed image obtained by photographing the projection surface from which the dark part or high-saturation part has been removed is obtained. And correcting the projected image.
(6) According to a sixth aspect of the present invention, there is provided a projector that corrects a projected image using a captured image obtained by capturing a projection surface on which a predetermined projected image is projected, and a projection corrected by the correcting unit. A projection unit that projects an image; and a detection unit that detects, based on the captured image, a dark portion of the projection surface or a high-saturation portion of the projection surface. When a dark portion or a highly saturated portion of the projection surface is detected, the brightness of the light source that projects the projection image is increased.

  According to the present invention, even if a part of the projection surface has a very dark (low brightness) part or a part with high saturation, the dynamic range of the entire projection image is corrected to be extremely narrow due to the influence of that part. Can be prevented.

  Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings. In the projector according to the present invention, when there is a very dark part (low brightness) or a part with high saturation in a part of the projection surface, the part is notified to the user.

-First embodiment-
FIG. 1 is a front view of a projector 1 according to an embodiment of the present invention. As shown in FIG. 1, a projection lens 111A constituting the projection optical system 111 (see FIG. 2) and a photographing lens 121A constituting the imaging optical system 121 (see FIG. 2) are provided on the front of the projector 1. Yes. The projector 1 projects projection information such as an image by a built-in projection unit 110 (see FIG. 2) toward a front screen or the like while being placed on a desk or the like.

  FIG. 2 is a block diagram illustrating the configuration of the projector 1. In FIG. 2, the projector 1 includes a projection unit 110, an imaging unit 120, a control circuit 101, a memory 102, an operation unit 103, an external interface (I / F) circuit 104, and a memory card interface (I / F). 105, and a memory card 150 is connected to the memory card interface 105.

  The control circuit 101 includes a microprocessor and its peripheral circuits. Based on the control program, the control circuit 101 performs a predetermined calculation using signals input from each part in the projector. Then, the control circuit 101 sends the calculation result to each part in the projector as a control signal, and controls the projection operation and the photographing operation of the projector 1. The control program is stored in a ROM (not shown) in the control circuit 101.

  The control circuit 101 includes an image processing unit 101A. The image processing unit 101A performs image processing on image data acquired via the external interface 104 or image data acquired from the memory card 150. Details of the image processing performed by the image processing unit 101A will be described later.

  The memory 102 is used as a working memory for the control circuit 101. The operation unit 103 includes buttons and switches, and sends operation signals corresponding to the operated buttons and switches to the control circuit 101. The memory card 150 can write, store, and read data according to instructions from the control circuit 101.

  The projection unit 110 includes a projection optical system 111, a liquid crystal panel 112, an LED light source 113, and a projection control circuit 114. The LED light source 113 illuminates the liquid crystal panel 112 with brightness according to the supply current. The liquid crystal panel 112 generates a light image according to the drive signal from the projection control circuit 114. The projection optical system 111 projects a light image emitted from the liquid crystal panel 112. The projection control circuit 114 sends a control signal to the LED light source 113 and the liquid crystal panel 112 according to an instruction from the control circuit 101.

  The projection unit 110 is configured to be able to project an image based on image data supplied from an external device via the external interface circuit 104 in addition to the image data stored in the memory card 150, and is instructed by the control circuit 101. Project an image. The image data image stored in the memory card 150 or the image data image supplied from the external device via the external interface circuit 104 is hereinafter referred to as a projection original image.

  The imaging unit 120 includes an imaging optical system 121, an imaging element 122, and an imaging control circuit 123, and images the projection plane in response to an instruction from the control circuit 101. The imaging optical system 121 forms a subject image on the imaging surface of the imaging element 122. As the image sensor 122, a CCD, a CMOS image sensor, or the like is used. The imaging control circuit 123 drives and controls the imaging element 122 according to an instruction from the control circuit 101 and performs predetermined signal processing on the image signal output from the imaging element 122.

  Image processing performed by the image processing unit 101A of the control circuit 101 will be described. In the image processing according to the embodiment of the present invention, color correction is performed so that the pattern and dirt on the projection surface are not noticeable when the projection original image is projected onto the projection surface. This color correction is performed based on the image of the projection plane captured by the imaging unit 120. The image processing unit 101A also corrects the tilt and distortion of the projected image. The tilt or distortion of the projected image is due to the fact that the optical axis of the projection optical system 111 does not coincide with the optical axis of the imaging optical system 121 or that the optical axis of the projection optical system 111 is not perpendicular to the projection plane. Occur. Since the image processing according to the embodiment of the present invention is characterized by the above-described color correction, the color correction will be mainly described.

  With reference to FIG. 3, a projected image that is visually recognized by projecting a projected image that has undergone image processing will be described. A description will be given assuming that a stain 31 is attached to the projection surface 30. When there is an extremely dark portion such as a spot 31 on the projection surface 30, as shown in FIG. 3A, an enclosing frame 32 surrounding the spot 31 is displayed, or an arrow 33 indicating the spot 31 is displayed. Or a warning is displayed. This warning display allows the user to turn off the stain 31 when the stain 31 forgets to turn off the whiteboard. If the spot 31 cannot be erased, another place can be used as the projection plane. As a result, as shown in FIG. 3B, the projected image 34 projected onto the projection plane 30 has good visibility. On the other hand, when the stain 31 is not erased or another place is not used as a projection plane, image processing of the projection original image is performed so that the stain 31 is not noticeable. As a result, as shown in FIG. 3C, the dynamic range of the projection image 35 becomes very narrow, and the visibility of the projection image 35 becomes very poor.

  Image processing in the embodiment of the present invention will be described with reference to the flowchart of FIG. The processing in FIG. 4 is executed in the control circuit 101 by a program that starts when the projector 1 starts processing for starting projection.

  In step S1, a geometric correction coefficient for performing geometric correction of the projection original image is calculated. Geometric correction refers to distortion of a projected image caused by the optical system optical axis of the projection unit 110 and the optical system optical axis of the imaging unit 120 not matching, or the optical system optical axis of the projection unit 110 with respect to the projection surface. This is a correction for eliminating tilt, distortion, etc. of the projected image due to non-verticality. Since the calculation method of the geometric correction coefficient is a conventional technique, the description thereof is omitted.

  Here, the image processing unit 101 </ b> A of the control circuit 101 performs an interpolation process so that the number of projected original images matches the resolution of the projector 1. Furthermore, the image processing unit 101A performs an interpolation process on the image captured by the imaging unit 120 so as to match the resolution of the projector 1. It is assumed that the projection original image subjected to the above-described interpolation processing is corrected as follows using the captured image subjected to this interpolation processing, and the corrected image is projected. This is to clarify the correspondence between the pixels of the projected image and the pixels of the captured image and increase the processing speed.

  In step S2, the projection characteristics of the projection unit 110 are calculated. The projection characteristics are characteristics indicating the relationship between the pixel values (R, G, B) of the input image and the colorimetric values (X, Y, Z) of the projection image reproduced on the projection plane. The colorimetric value is affected by illumination unevenness of the projection unit 110, the color and pattern of the projection surface, and the brightness of the projection surface by ambient illumination. Therefore, the projection unit 110 projects and projects a predetermined projection image (a black image, an R image, a G image, and a B image as described later) represented by known pixel values (R, G, B). The projected image on the surface is captured by the imaging unit 120. Colorimetric values (X, Y, Z) are detected from the photographed image to calculate projection characteristics. Then, the input image is corrected and projected by a correction coefficient calculated based on the projection characteristics. As a result, the projection image is not affected by the illumination unevenness of the projection unit 110, the color and pattern of the projection surface, and the brightness of the projection surface by ambient illumination. As a result, the user can appreciate the projected image that is expressed more closely than the appearance of the input image. Specific processing of the projection characteristics will be described later.

  In step S3, the projection plane is analyzed. A white image is projected from the projection unit 110 onto the projection plane, and the projected projection plane is photographed by the photographing unit 120. The photographed image is analyzed, and the extremely dark portion is extracted as a warning display area. Specific processing will be described later.

  In step S4, it is determined whether or not there is an extremely dark portion on the projection surface. If there is an extremely dark portion on the projection surface, an affirmative determination is made in step S4, and the process proceeds to step S10. If there is no extremely dark portion on the projection surface, a negative determination is made in step S4, and the process proceeds to step S5.

  In step S5, a correction coefficient for the projected image is calculated. In other words, using the projection characteristics obtained in step S2, correction to be performed on the input image so that the projection image reproduces the input image (projected original image) without being affected by the state of the projection surface or the ambient illumination environment. Calculate the coefficient. A projection image projected from the projection unit 110 is photographed by the photographing unit 120, and the photographed image is analyzed to calculate a correction coefficient of the projection image. This correction coefficient becomes the correction amount of the projection original image. Details of this processing will also be described later.

  In step S <b> 6, the image data of the projection original image is read from the external interface circuit 104 or from the memory card 150 and stored in the memory 102. In step S7, the projection original image data read in step S6 is corrected with the correction coefficient calculated in step S5. In step S8, the projection original image data corrected in step S7 is converted to analog, and a projection image is projected.

  In step S9, it is determined whether there is projection original image data to be projected next. If there is projection original image data to be projected next, an affirmative determination is made in step S9, and the process returns to step S6. If there is no projection original image data to be projected next, a negative determination is made in step S9, and the process ends.

  In step S10, a warning is displayed by displaying an enclosing frame surrounding the area extracted in step S3 or an arrow indicating the extracted area.

  In step S11, the presence / absence of user correction is determined. When the user takes a measure to remove the dark portion with the warning displayed in step S4 from the projection surface, the user operates the operation unit 103 to input to the projector 1 that the dark portion has been removed. Thereby, the control circuit 101 can determine the presence or absence of user correction. As described above, when the part with extremely low brightness on the projection surface is removed from the projection surface, if the part with extremely low brightness is forgotten to erase the whiteboard, the forgetting to erase is erased and the brightness is extremely dark. If the part cannot be erased, another place is set as the projection plane. If there is user correction, an affirmative decision is made in step S11 and the process returns to step S1. If there is no user correction, a negative determination is made in step S11, and the process returns to step S10.

  Next, steps S2, S3, and S5 will be described in more detail.

ただし、

-Calculation of projection characteristics-
The calculation of the projection characteristics performed in step S2 will be described.
When a projection image is generated from the input image data whose i-th pixel value is given by (R, G, B) _i and projected by the projection unit 110, the colorimetric values (i.e., colorimetric values of the projection plane corresponding to the i-th pixel value) X, Y, Z) _i is expressed by the following equation (1).

However,

Here, γ represents the gradation characteristic of the projection unit 110. M _pi represents a color conversion matrix for converting the pixel values (R ^γ , G ^γ , B ^γ ) _i of the projection unit 110 into the colorimetric values of the illumination of the projection unit 110. (X _kp , Y _kp , Z _kp ) _i represents the illumination condition of the projection plane including ambient illumination when a black image is projected by the projection unit 110. R * _i represents the reflectance characteristic of the projection surface.

  The subscript i has the following meaning. In the projector according to this embodiment, the projection surface is imaged by projecting a known image such as a white image or a black image, and based on the captured image, not only the unevenness of the reflectance due to the pattern of the projection surface, but also the projection unit 110 illumination unevenness, ambient illumination and in-plane unevenness of black spots are also corrected. Therefore, the subscript i is used to express different projection characteristics for each pixel area on the projection plane.

In the equation (1), (X _k , Y _k , Z _k ) is based on a projection plane photographed image when a black image ((R, G, B) _i = (0, 0, 0) _i ) is projected. To decide. Note that the colorimetric value of the projected image on the projection plane can be calculated by using a color conversion process determined in advance from the pixel value of the captured image. That is, if the profile of the captured image is sRGB, (X _k , Y _k , Z _k ) _i can be determined by applying normal sRGB conversion processing to the pixel values.

Similarly, an R image ((R, G, B) _i = (255, 0, 0) _i ), a G image ((R, G, B) _i = (0, 255, 0) _i ), and a B image A 3 × 3 matrix coefficient of the color conversion matrix M _i is determined from each captured image obtained by capturing the projection plane on which ((R, G, B) _i = (0, 0, 255) _i ) is projected. Specifically, the colorimetric values of the captured images (hereinafter referred to as projected captured images) on which the R image, G image, and B image are projected are respectively (X _r , Y _r , Z _r ), ( If X _g , Y _g , Z _g ) and (X _b , Y _b , Z _b ), the color conversion matrix M _i is expressed by the following equation (3).

-Analysis of projection plane-
The projection plane analysis performed in step S3 will be described.
If the projection surface has unevenness (hereinafter simply referred to as “unevenness”, including unevenness in the reflectance of the projection surface or illumination unevenness) or a pattern, the pixel values of the captured image obtained by photographing the projection surface are uniform. Instead, the pixel values correspond to the unevenness and the pattern. In other words, the maximum displayable color gamut varies with each pixel. In this embodiment, first, the maximum displayable color gamut range is determined. The luminance Y _i on the projection plane is calculated from the equation (1):

Therefore, displayable brightness range, (4) In the _equation, 0 ≦ _{R i, Y} i can take when shaken _{R i,} G i, the value of _{B i} in G i, a range of _{B i} ≦ 255 Determined by the range of values. _Usually, Y _r, Y _g, since a Y b> _{Y k,} displayable intensity range of each pixel is a white image _{((R, G, B)} i = (255,255,255) i) a projection The maximum displayable luminance can be obtained as _{YMAX, i} , and the display luminance when a black image is projected can be obtained as the minimum displayable luminance _{YMIN, i} .

For example, when the pattern of the projection surface is partially dark on the white surface as shown in FIG. 3A _, the histograms of Y _{MAX, i} and Y _{MIN, i} are calculated in the projection surface, as shown in FIG. And the histogram of FIG.

Here, when the projection original image is corrected so that the unevenness and the pattern on the projection surface disappear, the maximum luminance Y _MAX of the image after projection is MIN (Y _{MAX, i} ), and the minimum luminance Y _MIN is MAX (Y _{MIN, i} ). It is necessary to correct so that However, in this case, the dynamic range becomes very narrow, and the visibility of the projected image after correction is deteriorated (see FIG. 3C).

Therefore, an area where the brightness of the projection surface is lower than a predetermined maximum brightness threshold _Yth is extracted as a warning display area. The maximum brightness threshold Y _th may be a predetermined value (for example, Y _th = 0.2 for white brightness value Y = 1.0) regardless of the image, or the histogram of FIG. In this case, a luminance value that is equal to or greater than a predetermined ratio counted from the lower luminance is used, or a predetermined ratio (for example, 20%) of the maximum luminance Y _MAX = MAX (Y _{MAX, i} ) in the projection plane projection image plane. Or may be determined as

-Calculation of projection image correction coefficient-
The calculation of the projection image correction coefficient performed in step S5 will be described.
If the color space of the projection original image is sRGB, the input pixel value (R, G, B) to the projection unit 110 after correction is applied to the pixel value (R ₀ , G ₀ , B ₀ ) of the projection original image. _i can be calculated by the following equation.

Using M _i , (X _k , Y _k , Z _k ) _i calculated in step S2 and Y _MAX calculated in step S3, a correction coefficient for correcting the projection original image is calculated according to equation (5). . Note that the pixel value at the pixel position i where the luminance Y _{MIN, i} = Y _MIN when a black image is projected onto the projection plane is the black point (X _k0 , Y _k0 , Z _k0 ) of the projected image.

M _{sRGB → XYZ} is a conversion matrix from sRGB to XYZ determined in advance by the standard. For simplicity, sRGB is described as γ = 2.2, but may be calculated by a combination of a linear function and γ = 2.4 as standard.

  Note that after displaying a warning in step S10, the process proceeds to step S11. If there is a user correction, step S11 is affirmatively determined and the process returns to step S1, but after displaying a warning in step S10, the process proceeds to step S1. You may make it return. If there is an extremely dark portion on the projection surface, the control circuit 101 repeats Steps S1 to S4 and Step S10 from when the projector 1 is turned on until the projection original image signal is input. . However, when there is no part with extremely dark brightness on the projection surface due to the user's response or the like, the process proceeds from step S4 to step S5, and the projector 1 automatically starts projection. In this case, since the user does not need to input that user correction has been performed through the operation unit 103, convenience for the user is improved.

According to the embodiment described above, the following operational effects can be obtained.
When there is a dark portion on the projection surface, a warning portion is displayed on the projection surface to notify that there is a dark portion and a dark portion. As a result, the user can take a countermeasure to remove the dark portion from the projection surface, and the dynamic range of the entire projected image can be prevented from being extremely narrowly corrected due to the dark portion. it can.

  As a countermeasure for removing the dark portion from the projection surface of the user, if the warning-displayed portion is forgotten to erase the whiteboard, the forgetting to erase can be erased. In addition, when the dark part displayed with the warning cannot be erased, the projection plane can be shifted from the dark part.

The reason why the user can prevent the dynamic range of the entire projected image from being corrected to be extremely narrow by removing the dark portion from the projection surface is as follows. When an image is projected onto the projection plane 30 shown in FIG. 3A (the luminance distribution when projecting a white image is FIG. 5A and the luminance distribution when projecting a black image is FIG. 5B), the pattern of the projection plane is shown. If the correction is made so as to make it inconspicuous, the luminance reproduction range of the projected image is changed from the maximum luminance Y _MAX = MIN (Y _{MAX, i} ) = Y2 to the minimum luminance Y _MIN = MAX (Y _{MIN, i} ) = Y3, and the dynamic range Becomes narrower. However, when the dark area 31 in the upper right of FIG. 3A can be removed from the projection plane 30 by user correction, the luminance distribution during white image projection is improved from FIG. 5A to FIG. 5C. The reproducible luminance range can be expanded from the maximum luminance Y _MAX = MIN (Y _{MAX, i} ) = Y1 to the minimum luminance Y _MIN = MAX (Y _{MIN, i} ) = Y3. In other words, the reproducibility of the projected image 34 is improved by eliminating unnecessary overcorrection by simply extracting and warning 32 and 33 the correction difficult region 31 with respect to the projection surface 30 having the low brightness and difficult correction region 31. can do.

-Second Embodiment-
In the first embodiment, the user has taken a measure of removing a portion where the brightness of the projection surface is extremely dark from the projection surface. However, in the second embodiment, by reducing the projection size of the projection screen projected by the projection unit 110 by the projector, a portion where the brightness of the projection plane is extremely dark is removed from the projection plane. This automates the process of removing the extremely dark portion of the projection surface from the projection surface, and improves the convenience of the projector 1. For example, as shown in FIG. 6A, when a spot 31 is attached to the projection surface 30, the projection size of the projection image 36 is set so as not to overlap the spot 31 as shown in FIG. Make it smaller. Thereby, since the projection original image is not corrected so that the dynamic range of the projection image in consideration of the spot 31 is very narrow, it is possible to prevent the visibility of the projection image from being deteriorated.

  Image processing for reducing the projection size of the projection image will be described with reference to the flowchart of FIG. The processing in FIG. 7 is executed in the control circuit 101 by a program that starts when the projector 1 starts processing for starting projection. The same processes as those in FIG. 4 are denoted by the same reference numerals, and differences from the processes in FIG. 2 will be mainly described.

  If a positive determination is made in step S4, the process proceeds to step S21. In step S21, the projection size of the projection image is reduced by a predetermined ratio. Then, the process returns to step S1.

  Even if the projection size of the projection image is reduced to a predetermined size, the extremely dark part of the projection plane cannot be removed from the projection plane (for example, the extremely dark part is near the center of the projection plane) ), As in the embodiment of the present invention, a warning may be displayed for a portion with extremely low luminance, and the user may be allowed to take measures to prevent a portion with extremely low luminance from being included on the projection surface. .

-Third embodiment-
In the first embodiment, the user has taken a measure of removing a portion where the brightness of the projection surface is extremely dark from the projection surface. However, in the third embodiment, by moving the projection position of the projection screen projected by the projection unit 110 by the projector and reducing the projection size of the projection image, a portion with an extremely dark brightness on the projection plane is projected. Remove from. This automates the process of removing the extremely dark portion of the projection surface from the projection surface, and improves the convenience of the projector 1. In addition, the projection size of the projection screen can be increased compared to the second embodiment described above. For example, as shown in FIG. 8A, when a spot 31 is attached to the projection surface 30, the projection position of the projection image 37 is set so as not to overlap the spot 31 as shown in FIG. Move and reduce projection size. Thereby, it is possible to prevent the dynamic range of the projection image from becoming very narrow and the visibility of the projection image from being deteriorated. In this case, since the projector 1 has to consider the movement of the projection image, the imaging unit 120 captures a wide area (hereinafter referred to as a wide area projection area) 40 from the projection surface 30 and the luminance is extremely dark. Detect part.

  With reference to the flowchart of FIG. 9, image processing for moving the projection position of the projection image and reducing the projection size will be described. The process of FIG. 9 is executed in the control circuit 101 by a program that starts when the projector 1 starts a process for starting projection. The same processes as those in FIG. 9 are denoted by the same reference numerals, and differences from the processes in FIG. 9 will be mainly described.

  After step S1, the process proceeds to step S31. In step S31, the projection characteristics in the wide area projection area are calculated. A projection image that is projected from the projection unit 110 and has a larger projection size than usual, that is, a projection image that covers a wide-area projection area is captured by the imaging unit 120, and a colorimetric value is detected from the captured image. Projection characteristics are calculated.

  In step S32, the wide projection area is analyzed. A white image is projected from the projection unit 110 onto the wide projection area, and the projected wide projection area is photographed by the photographing unit 120. The photographed image is analyzed, and a portion with extremely dark luminance is extracted from the wide area projection area.

  In step S33, the projection position and the projection size of the projection screen are determined such that the projection screen does not include an extremely dark portion. Specifically, the position and size of the rectangular shape having the same aspect ratio as that of the projection screen are changed within the wide projection area so as not to include an extremely dark portion. Then, the projection position and the projection size of the projection image are determined so that the position and size of the projection screen coincide with the largest rectangular shape whose position and size are changed. Then, the process proceeds to step S2.

  Since the projection position and the projection size of the projection screen are determined so that the projection screen does not include an extremely dark portion, the process proceeds to step S5 after step S3.

  Also in this case, when the projection surface of the projection image is reduced to a predetermined size and a portion where the brightness of the projection surface is extremely dark cannot be removed from the projection surface, the brightness is extremely low as in the embodiment of the present invention. A warning display indicating a dark part may be displayed on the screen to allow the user to take action.

The above embodiment can be modified as follows.
(1) In step S3 of the first and second embodiments and step S32 of the third embodiment, a projection plane on which a white image is projected is photographed in consideration of correction of the luminance direction, and the photographing is performed. The image was analyzed and a part with extremely dark brightness was extracted. However, R image (all pixel values, R = 255, G = B = 0), G image (all pixel values, G = 255, R = B = 0) and B image (all pixel values, B = 255, R = G = 0), and an image obtained by photographing the projection plane on which each image is projected may be analyzed to extract a portion with extremely high luminance. As a result, it is possible to easily extract such a region that is difficult to correct for a projection surface that has a high saturation and a region that is difficult to correct. Then, by moving the projection surface from a region where saturation correction is difficult, overcorrection that narrows the dynamic range of saturation can be eliminated, and the reproducibility of the projected image can be improved.

(2) In the first embodiment, a warning is displayed when there is an extremely dark portion on the projection surface. However, the warning display may be performed in consideration of the area and / or position of the extremely dark portion. Depending on the area or position of the extremely dark portion, there is a case where it does not matter even if it looks on the projection screen. In such a case, the dynamic range of the projected image can be obtained by performing image processing of the projected original image while ignoring the extremely dark portion without performing a warning display and letting the user remove the extremely dark portion. This is because it is never too narrow.

(3) The threshold value _{Yth in} step S3 of the first to third embodiments is set so that the characteristics of the projection unit 110 (permissible range of illumination unevenness, defects, etc.) and the correction method (the darkest part of the projection surface are not noticeable). The projection original image may be corrected, or may be changed depending on the situation (size, position, amount, etc.) of the dark part.

(4) When there is an extremely dark portion on the projection surface, the power supplied to the LED light source 113 of the projection unit 110 may be increased to increase the brightness of the LED light source 113. When the image processing of the projection original image is performed so that the extremely dark part having the luminance is inconspicuous, the dynamic range of the projection image is narrowed as described above. However, even in such a case, by increasing the brightness of the LED light source 113, the dynamic range of the projected image can be widened, and the visibility of the projected image can be improved.

  The above description is merely an example, and the present invention is not limited to the configuration of the above embodiment.

1 is an external view of a projector according to an embodiment of the present invention. It is a block diagram explaining the structure of the projector in embodiment of this invention. It is a figure explaining the projection image visually recognized when the projection image processed by the image processing in the 1st Embodiment of this invention is projected. It is a flowchart for demonstrating the image processing in the 1st Embodiment of this invention. It is a figure which shows distribution of the brightness | luminance at the time of white image projection. It is a figure for demonstrating the image processing which removes the part where the brightness | luminance of a projection surface is extremely dark from a projection surface by reducing the projection size of the projection screen in the 2nd Embodiment of this invention. It is a flowchart for demonstrating the image process which removes the part where the brightness | luminance of a projection surface is extremely dark from a projection surface by reducing the projection size of the projection screen in the 2nd Embodiment of this invention. FIG. 10 is a diagram for explaining image processing for removing a portion where the brightness of the projection surface is extremely dark from the projection surface by moving the projection position of the projection image and reducing the projection size in the third embodiment of the present invention. is there. FIG. 11 is a flowchart for explaining image processing for removing a portion where the brightness of the projection surface is extremely dark from the projection surface by moving the projection position of the projection image and reducing the projection size in the third embodiment of the present invention. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projector 30 Projection surface 31 Spot 34-37 of a projection surface Projected image 101 Control circuit 102 Memory 103 Operation part 104 External interface 105 Memory card interface 110 Projection unit 120 Imaging unit

Claims (6)

Correction means for correcting the projection image using a photographed image obtained by photographing the projection surface on which the predetermined projection image is projected;
Projection means for projecting the projection image corrected by the correction means;
Detecting means for detecting, on the basis of the captured image, a portion where the luminance of the projection surface is dark or a portion of the projection surface having high saturation;
A projector comprising: an informing means for informing a user of a dark portion of the detected projection surface or a highly saturated portion of the projection surface. Correction means for correcting the projection image using a photographed image obtained by photographing the projection surface on which the predetermined projection image is projected;
Projection means for projecting the projection image corrected by the correction means;
Detecting means for detecting, on the basis of the photographed image, a portion where the luminance of the projection surface is dark or a portion where the saturation of the projection surface is high;
Control means for controlling the size of the projection image projected onto the projection plane so that the projection image is not superimposed on a portion where the brightness of the detected projection plane is dark or a portion with high saturation of the projection plane. A projector characterized by that. Correction means for correcting the projection image using a photographed image obtained by photographing the projection surface on which the predetermined projection image is projected;
Projection means for projecting the projection image corrected by the correction means;
Detecting means for detecting, on the basis of the captured image, a portion where the luminance of the projection surface is dark or a portion of the projection surface having high saturation;
Control means for controlling the projection position and size of the projection image projected on the projection plane so that the projection image is not superimposed on a portion where the luminance of the detected projection plane is dark or a portion with high saturation of the projection plane And a projector. The projector according to claim 2 or 3,
Even if the size of the projection image is made smaller than a predetermined size by the control means, the projection image is projected onto the projection surface on a portion where the brightness of the detected projection surface is dark or a portion where the saturation of the projection surface is high And a notifying means for notifying a user of a portion where the brightness of the detected projection surface is dark or a portion where the saturation of the projection surface is high. The projector according to claim 1 or 4,
An input means for a user to input that the dark part or the highly saturated part has been removed from the projection plane;
The correction means, when the input means inputs that the dark part or the high-saturation part has been removed from the projection surface, the correction part removes the dark part or the high-saturation part from the projection surface. A projector that corrects a projected image using a photographed image obtained by photographing. Correction means for correcting the projection image using a photographed image obtained by photographing the projection surface on which the predetermined projection image is projected;
Projection means for projecting the projection image corrected by the correction means;
Detecting means for detecting a portion where the brightness of the projection surface is dark or a portion where the saturation of the projection surface is high based on the captured image;
The projection unit increases the brightness of a light source that projects the projection image when the detection unit detects a portion with low brightness on the projection surface or a portion with high saturation on the projection surface. Projector.

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