JP2009105679A - Image processing apparatus and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To project image data as an image having good color reproducibility from an observer's view point by correcting the image data to be displayed based on the type of a projection screen and the direction of the observer's view point. <P>SOLUTION: A screen information storing section 105 stores the material of the projection screen and screen gain information for each angle of view point. By inputting the information which specifies the observation direction of an observer relative to the projection screen, the information is stored in an observation position information storing section 104. A correction table for projecting the image data to be projected which is stored in a section 103 for storing images to be projected is generated based on the information stored in the screen information storing section 105 and the observation position information storing section 104, and the correction table is stored in a correction table storing section 106. The images stored in the section 103 for storing images to be projected are corrected according to the correction table stored in the correction table storing section 106. The corrected image data is output into a projector 114 and is projected on the projection screen used by the user. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for generating an image to be projected onto a projection screen using an image projection unit.

  In recent years, in addition to the spread of personal computers, peripheral digital devices such as color printers, digital cameras, digital videos, and image digital devices such as monitors and projectors have become widespread. In particular, projectors are now indispensable devices for presentations such as conference rooms and showrooms at office sites. In addition, it is often used for effective window advertisements on streets and the like, and a new method of using a projector has been proposed. Furthermore, even for general users, there are increasing cases of using projectors in entertainment scenes, such as installing a home theater for watching TV or movies. Along with the spread of these digital devices in various fields, the level of demand for color reproduction of users has increased rapidly in recent years as each device has become more functional and more accurate. Realization of accurate color matching is required.

  Needless to say, adjustment using hardware and software is indispensable for realizing high-precision color matching. In color matching using a projector, it is common to perform focus adjustment, resolution adjustment, video position adjustment, keystone adjustment, white balance and sharpness adjustment, etc. by hardware adjustment. In software adjustment, a method of creating an ICC profile or the like by displaying a color patch on a screen from a projector using a commercially available application and measuring the color patch with a measuring instrument is common.

  On the other hand, it is known that color matching using a projector is greatly influenced not only by the specifications of the projector body but also by the screen material to be projected. The declination characteristic peculiar to the screen material is different for each screen material. One example of a numerical value representing the reflection characteristic of the screen material is called a screen gain. The screen gain is different for each kind of general screen material such as beads, mats, and pearls. In particular, with respect to the peak gain showing the highest numerical value among the screen gain values, the difference in the type of screen appears remarkably. For this reason, the reflection characteristics of the screen obtained also differ depending on the viewing position of the user, so that it is very difficult to always obtain a certain high accuracy and ideal color reproduction in the projector projection environment desired by the user.

Conventionally, Patent Literature 1 and Patent Literature 2 are known as methods for solving the problems in color matching using these projectors. Patent Document 1 is a technique for performing optimal light control in accordance with the type of image projected by the illumination device, ambient brightness, and the like. And in this patent document 1, according to information, such as the kind of image | video to view, the brightness of viewing environment, a screen gain, etc., the range (dimming range) in which the light quantity adjustment is permitted is set optimally. . On the other hand, Patent Document 2 is a video display device installed in a vehicle interior, without interfering with a vehicle interior structure such as a dashboard, and even when projected over a wide range, the image viewed from the driver is not uncomfortable, It is intended to project as a uniform surface.
JP2004-354882 JP 2006-88722 A

  However, in patent document 1, it is the technique which adjusts the light quantity of an illuminating device on hardware, and the special adjustment mechanism was required for illuminating device itself.

  On the other hand, in patent document 2, it is limited to the video display apparatus attached to the passenger compartment, and lacks versatility because it is not a system that can be used in any environment. Further, although the unevenness of the surface on which the image is displayed is taken into consideration, the difference in color reproduction due to the micro property such as the screen material is not emphasized.

  The present invention has been made in view of such problems, and intends to provide a technique that makes it possible to project an image with a good color according to the type of the projection screen and the observation position of the observer. Is.

In order to solve this problem, for example, an image processing apparatus of the present invention has the following configuration. That is,
An image processing apparatus having projection means for projecting an image on a projection screen,
Position information input means for inputting position information for specifying the observer's viewpoint direction with respect to the projection screen;
Characteristic information input means for inputting information indicating display characteristics of each viewpoint direction with respect to the projection screen;
Correction table calculation means for calculating a correction table for correcting image data to be projected based on information input from each of the position information input means and characteristic information input means;
Correction means for correcting image data to be output to the projection means according to the correction table calculated by the correction table calculation means.

  According to the present invention, by correcting the image data to be displayed based on the type of the projection screen and the viewpoint direction of the observer, the image can be projected as an image having good color reproduction from the viewpoint of the observer. become.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
The image processing apparatus according to the embodiment will be described assuming that a general-purpose information processing apparatus represented by a personal computer and a projector are connected thereto. Since the hardware configuration of the personal computer will not be described, a functional block configuration that functions as an image processing apparatus when the information processing apparatus executes the application of the present embodiment will be described below with reference to FIG. Show and explain.

  In the figure, reference numeral 101 denotes a personal computer (hereinafter, PC). The PC 101 includes an application storage unit 102, a projection image storage unit 103, an observation position information storage unit 104, a screen information storage unit 105, a correction table storage unit 106, a correction image generation unit 107, and a correction image data storage unit 108. The image analysis unit 109, the patch data storage unit 110, the screen material storage unit 111, the screen gain storage unit 112, and the target table storage unit 113 are also included. Among these, the corrected image generation unit 107 and the image analysis unit 109 are portions executed by the processor in the PC, and the other storage unit is stored in the main memory or the hard disk. In addition, a projector 114 as a projection unit, a monitor 115, and a colorimeter 116 are connected to the PC 101.

  The screen information storage unit 105 includes a screen gain storage unit 112 as screen characteristic information. However, any information indicating screen characteristics is not limited to screen gain, and arbitrary information is stored. May have been. However, in order to facilitate understanding, the embodiment will be described assuming that the screen characteristic information is screen gain information.

  First, the projector projection image creation processing in the above configuration will be described below.

  When the image application stored in the application storage unit 102 receives a user's activation instruction, the OS (operating system) loads the program into the main memory and executes it, thereby starting this control process. The activated application performs the following processing.

  First, when the application is activated, the user designates an image to be projected on the screen on the application using a GUI displayed on the monitor 115 by the application. As a result, the designated image data is stored in the projection image storage unit 103.

  Next, the user selects a screen material on which an image is projected on the GUI by the application. The selected screen material is stored in the screen material storage unit 111 in the screen information storage unit 105. Subsequently, the user is caused to input observation position information for specifying at which position (angle) to observe with respect to the screen. The input observation position information is stored in the observation position information storage unit 104.

  The screen gain value obtained by quantifying the reflection characteristics of the screen is stored in advance in the screen gain storage unit 112 as a default value corresponding to the screen material selected above. However, the screen gain value desired by the user can be read on the application. Further, as a means for obtaining the optimum screen gain value for the image projected by the user, the projected image is analyzed by the image analysis unit 109, and the patch image generation process for obtaining the optimum screen gain value for the image is executed. The generated patch image is stored in the patch data storage unit 110. The patch data in the patch data storage unit 110 is displayed on the screen via the projector 114 when a measurement start button on the application is pressed. By performing color measurement on the patch displayed on the screen using the colorimeter 116, it is possible to obtain a screen gain value. The default screen gain value associated with the screen material, the screen gain value read by the user, or the screen gain value obtained by the user measuring the patch is stored in the screen gain storage unit 112. The As described above, a projection image creation (correction) table is created on the basis of information input on the application and information stored in the target table storage 113 such as what color reproduction is targeted. And stored in the correction table storage unit 106.

  The correction image generation unit 107 uses the correction table stored in the correction table storage unit 106 calculated by the above method to generate projector projection correction image data that is optimal for the currently used screen material and observation position, and performs correction. Stored in the image data storage unit 108. The image data (corrected image data) stored in the corrected image data storage unit 108 is output to the projector 114 and projected onto the screen.

  In the following, detailed projector projection image creation processing will be described with reference to the flowchart of FIG. 2, the application outline diagram of FIG. 3, and the screen gain diagrams of FIGS. 13 (a) and 13 (b).

  First, in step S201, the projector projection image creation application shown in FIG. 3 stored in the application storage unit 102 is activated. That is, according to a user instruction, an application program is loaded into the main memory, and the processor starts executing the program. As a result, the application displays a GUI window as shown in FIG. 3 on the monitor 115 and receives an instruction input from the user.

  In step S202, the user designates an image to be projected on the screen by the projector from the input field 301 in FIG. In the input field 301, the file name of the image data to be projected is input from the keyboard with a path. However, a target file may be selected by displaying a dialog box and using a pointing device such as a mouse to follow the hierarchy of the file system. Hereinafter, data input using a keyboard or a pointing device is simply referred to as input or selection.

  In step S203, the screen material on which the image output from the projector is projected is selected from the candidates in the selection box 302 in FIG. As screen materials that can be selected, users who use screen materials other than “Beads”, “Matte”, “Pearl”, etc., which are representative materials currently available from screen manufacturers, are available in advance. Is an “arbitrary material” (or any kind) and is prepared for choice. Note that the selectable screen material described in this embodiment is merely an example, and the same processing can be performed even if an arbitrary material to be released in the future or a screen with an arbitrary name is added as an option. .

  In step S204, position information on which position the user observes with respect to the screen is input in the input field 303 of FIG. In this input, a numerical value indicating an angle is input. When a numerical value indicating an angle is input, an asterisk is displayed at a corresponding position on the image simulating the observation environment as in the region 304 in FIG. 3 and can be confirmed by the user. Conversely, when a pointing device is designated as a position on the area 304, a star is displayed at that position, and as a result, a numerical value indicating the calculated angle is displayed in the input field 303. That is, the observation position can be designated by using either of the above two methods.

  Note that the angle of the observation position is 0 ° in the vertical direction of the screen surface with respect to the center of the screen. Then, a clockwise direction at the center is a positive angle, and a counterclockwise direction is a negative angle. However, this is an example, and the reference position may be provided anywhere.

  In step S205, a screen gain value suitable for the screen material is acquired. It is assumed that the screen gain value has a value associated with the screen material (pearl, mat, bead, etc.) selected in step S203 as a default value in the screen gain storage unit 112. In order to respond to a user who desires high-precision color reproduction, the selection box 302 in FIG. 3 displays “arbitrary material” as one of the candidates among the screen material options. When this candidate is selected, the screen gain value can be set by two methods (first selection method). One is to specify a file storing screen gain values obtained in advance by an arbitrary method by inputting a file name with a path in the input field 306 of FIG. The other is to obtain the screen gain value in a desired environment by pressing the measurement start button 305 in FIG. 3 with the screen gain value corresponding to the image configuration to be projected and the screen material to be used. . The latter further includes a step of selecting either the first measurement method or the second measurement method (second selection method). The method for acquiring (measuring) the screen gain value will be described in detail later. The screen gain value described here is a numerical value indicating reflection characteristics that differ for each screen material. The brightness obtained when a certain amount of light is applied to what is called a perfect diffuser that returns almost the same reflectivity in the direction of 180 ° vertically and horizontally is set to 1.0, and the irradiation angle to the screen is changed under the same conditions. The ratio with the brightness | luminance obtained was shown. In general, as shown in FIGS. 13A and 13B, it is known that the screen gain value is different for each material of the screen. In particular, with respect to the peak gain showing the highest value among the screen gain values, the properties of the screen material are prominent. Further, as can be seen from FIGS. 13A and 13B, it is known that the reflection characteristics for each screen material differ depending on the observation angle.

  In step S206, a correction table for correcting the projection image is created from the screen gain value of the screen gain storage unit 112 obtained in step S205 and the target table data of the target table storage unit 113. The created correction table is stored in the correction table storage unit 106. The correction table creation method will be described in detail later.

  In step S207, by pressing the correction image creation button 307 in FIG. 3, the correction image generation unit 107 creates a projection correction image corresponding to the image data to be projected designated by the user by a predetermined method. . That is, using the projection image data in the projection image storage unit 103, the observation position information in the observation position information storage unit 104, and the correction table in the correction table storage unit 106, the screen material and observation position currently used by the user are used. The optimum projector projection image data is created. The created corrected image data is stored in the corrected image data storage unit 108, output to the projector 114, and displayed on the screen. The method of creating corrected image data for projection performed by the corrected image generation unit 107 will be described in detail later.

  When the end button 308 in FIG. 3 is pressed, the projector projection image creation operation is ended.

  Hereinafter, the screen gain value acquisition method in step S205 will be described with reference to FIGS. 3, 4, 5, 6A, 6B, 7, 8, and 9. FIG.

  First, description will be made with reference to the flowchart of FIG.

  In step S401, regarding the screen gain value, it is selected whether to use a default value associated with a screen material provided in advance or an arbitrary value instead of the default value. The user selects any one of “beads”, “matte”, “pearl”, and “arbitrary material” in the selection box 302 of FIG.

  Among these, when “beads”, “matte”, or “pearl” is selected as the screen material, the process proceeds to step S402. On the other hand, when “arbitrary material” in the selection box 302 is selected, the areas 305 and 306 in FIG. 3 are usable (active) on the application, and the button can be pressed or the file can be read. ) Proceed to step S404.

  In step S <b> 402, the screen material storage unit 111 acquires which screen material (three types of “beads”, “matte”, and “pearl” in the present embodiment) has been selected by the user.

  In step S403, based on the screen material information acquired in step S402, default screen gain information stored in the format shown in FIG. 8 associated with the screen material is acquired from the screen gain storage unit 112. That is, steps S402 and S403 function as characteristic information input means for the projection screen.

  On the other hand, when the process proceeds to step S404, it is selected whether to acquire the screen gain value in the current user observation environment or to read the screen gain information file already acquired by an arbitrary method. The former corresponds to the case where the measurement start button 305 is pressed, and the latter corresponds to the case where a file name with a path is input in the input field 306.

  When the screen gain value is measured in the user environment, the process proceeds to step S405. In the case where screen gain information already acquired by an arbitrary method is input without performing measurement, the process proceeds to step S409.

  When the process proceeds to step S405, a GUI (not shown) is displayed, and the user is allowed to select whether or not to analyze the projection image. When it is designated to perform image analysis, it is a case where the user wants to obtain a screen gain value that is optimal for the projection image and has a very high accuracy. In this case, the process proceeds to step S406. On the other hand, when an arbitrary screen material is used, but it is desired to obtain a normal screen gain value representing the declination characteristic of the screen regardless of the configuration of the projected image, the process proceeds to step S408.

  The selection of whether to obtain a screen gain value by creating and measuring a patch optimal for a projected image or by acquiring the screen gain value by measuring the screen material itself was as follows. That is, after detecting the pressing of the measurement start button 305 in the figure, a GUI that can be selected from two types of measurement methods such as “projection image applied patch measurement” or “screen material measurement” is displayed, and the user selects one of them. To do.

  In step S406, if it is determined in step S405 that analysis of the projection image is to be performed, the configuration of the projection image data is first analyzed to obtain a screen gain value. The image analysis method may be any method. For example, a means for performing image analysis using a histogram and determining the most pixel data among the pixel data constituting the image as a representative pixel value of the image may be used (see the image in FIG. 5). Alternatively, the image may be divided into regions, and an average value of pixels included in the divided region or a pixel value included most in the region may be calculated (see the image in FIG. 6A). Patch data is created based on the result of image analysis performed by any method described above. The patch data may be one piece of patch data or one piece of patch data for the number of area divisions for one image. In the former, as described above, as a result of the histogram analysis of the image, a patch may be created from one color of the most pixel data among all the pixel values included in the image. In the latter, as described above, the image is divided into regions (see FIG. 6A), and the average value of the pixels included in each divided region, or the pixel value included most in the region, It may be patch data in the area. Although an example has been shown here regarding the optimal patch data calculation method in the divided area, any method may be used as the calculation method. Further, a method for dividing the latter projected image into a plurality of regions, creating patch data, and calculating a screen gain value will be described in detail in the second embodiment. Therefore, in the following, a method for acquiring a screen gain value from one piece of patch data optimal for a projection image will be described as an example.

  In step S407, the patch is measured based on the patch data created in step S406. The type of device for measuring the patch may be any device (for example, an optical detection device such as a video camera) as long as the luminance value can be acquired. Now, it is assumed that the screen gain value to be acquired is in the range of −60 ° to 60 ° in the present embodiment. Here, the projector is fixed to the front (angle 0 degree) with respect to the center position of the screen, and only the angle of the colorimeter (with the measurement direction of the colorimeter facing the center position of the screen). To obtain the luminance value at each angular position. 60 ° is an angle positioned in the direction of 60 ° clockwise when the direction perpendicular to the screen is 0 °. On the other hand, −60 ° is an angle positioned in the direction of 60 ° counterclockwise when the direction perpendicular to the screen is 0 ° (see FIG. 7). The projector is installed at an arbitrary distance at a position of 0 ° with respect to the screen, and the patch is displayed at the center of the screen. In this proposal, the luminance value obtained when a certain amount of light is applied to the complete diffuser plate under a certain environment is defined as Tcd.

First, it is measured from −60 ° which is the lower limit of the measurement range. First, a projector is installed at a position perpendicular to the screen. The distance between the screen and the projector is a distance desired by the user. Subsequently, when the position connecting the projector installation position and the screen center point is set to 0 °, the measuring device is installed at an angle moved 60 ° counterclockwise on the same arc. When the measurement environment is ready, start measurement at the above position. The measurement method shall be in accordance with the usage method of the measuring equipment to be used. The luminance value at −60 ° measured by the above method is Y _-60 cd. Since the screen gain value is expressed as a ratio with the luminance value measured at the target position when the luminance value obtained when a constant light is applied to the complete diffuser under the same condition is “1”, The screen gain value at −60 ° can be expressed as Y− ₆₀ / T = N− ₆₀ . Similarly, the screen gain value at each angular position can be calculated by changing the measurement position in the range (angle) to be acquired and performing the measurement at each measurement position (angle) by a predetermined method. . In this proposal, measurement and calculation of the screen gain value are performed for each viewpoint direction in the range of −60 ° to 60 ° and 10 ° intervals. However, the screen gain range to be acquired and the data interval to be acquired may be set arbitrarily.

  If the process proceeds to step S408, no patch image is projected, that is, the projection image is not analyzed, and an arbitrary screen gain value used by the user is measured according to a normal screen gain acquisition method. Get more. The measurement object is the screen material itself, and the measurement area is the center of the screen. Under the above conditions, the measurement angle is changed by 10 ° from −60 ° to 60 °, and measurement is performed. Regarding the detailed screen gain calculation method when the luminance value obtained when the light is irradiated on the complete diffuser plate under the same conditions from the luminance value acquired at each measurement position, step S407 and A similar technique is used.

  When the process proceeds to step S409, the screen gain value data acquired in advance by the user by an arbitrary method is acquired with reference to the input in the input field 306 in FIG.

  For the sake of convenience, the screen gain value obtained in this proposal will be described as data at 10 ° intervals in the range of −60 ° to 60 °. The screen gain data range and interval that can be input by the user may be arbitrary, and data is deleted and interpolated from the acquired screen gain value in accordance with the application specifications. Regarding data deletion, processing such as truncation is performed except for necessary data. In addition, regarding data interpolation, any method may be used. For example, an angle gain value between two actually measured gain values may be calculated by linear interpolation. For example, when it is desired to calculate a screen gain value of −55 ° which is an angle between −60 ° and −50 °, the average value of the screen gain values of −60 ° and −50 ° is calculated as the screen gain of −55 °. Calculated as a gain value. The method for acquiring the screen gain value by the user may be a method acquired from measurement of an arbitrary patch or the like performed by the user himself / herself, or downloads information published from a document or a screen manufacturer used by the user. You may use what you did.

  In step S410, the screen gain value acquired in any of steps S403, S407, S408, and S409 is stored in the screen gain storage unit 112.

  The screen gain storage unit 112 stores the screen data acquired in step S403 in the format shown in FIG. 8, while the screen data acquired in step S407 or step S408 has the format shown in FIG. Is stored. In the present embodiment, it is assumed that screen gain values at intervals of 10 ° are associated with each other and stored in the screen gain storage unit 112 in the range of −60 ° to 60 °, and will be described below.

  Hereinafter, the correction table calculation (creation) method in step S206 will be described in detail with reference to FIG. 8, FIG. 10, and FIG.

  For the calculation of the correction table, a color conversion table (lookup table or the like) stored in the target table storage unit 113 and capable of reproducing an ideal color is used. In addition, the observation position (angle) information stored in the observation position information storage unit 104 such as the position at which the user observes the screen, and the screen gain storage unit 112 acquired by a predetermined method in step S205 are stored. Stored screen gain information is also used. The target table in the target table storage unit 113 is a certain ideal image obtained at a position in the vertical direction (0 ° position) with respect to the screen under the conditions projected using the projector and the screen used by the user. It is assumed that a LookUpTable (hereinafter referred to as an ideal LUT) from a device-dependent space to a device-independent space that enables accurate color reproduction is stored. The ideal LUT has a data structure as shown in FIG. 10 that describes the correspondence between the color coordinate data of the grid points in the RGB color space and the coordinate values of the L * a * b * color space reproduced by the grid points. Composed. The R / G / B value step is described at the head of the data structure, and thereafter, the color coordinate L * value, a * value, and b * value corresponding to each grid point are in the order of R, G, and B. Nested with This data structure is schematically represented in the RGB color space as shown in FIG. In this embodiment, the target table is described as being in the LUT format, but other relational expressions indicating an ideal output characteristic may be stored, and the table format is not limited. Shall. The device-independent space described in the LUT format is now described as a Lab space. However, any data space stored in the target table, such as an XYZ space or a Jch space, which is a device-independent space, is used. It does not matter if it is a type.

  Assume that the screen material used by the user is selected as “beads” in the selection box 302 of FIG. At this time, the screen gain value refers to the uppermost value in FIG. Also, assuming that the ideal LUT achieves ideal color reproduction in the vertical direction, that is, at a position of 0 ° with respect to the projector used by the user and the bead screen of the same material, the bead at the above position is used. The screen gain value of the screen is 1.6.

  On the other hand, it is assumed that the value input by the user in the input field 303 of FIG. 3 and stored in the observation position information storage unit 104 is −60 °. In the uppermost table of FIG. 8, the screen gain value at −60 ° is 0.8. Now, compared with the screen gain value at the 0 ° position where ideal color reproduction is possible, the value is 0.8 / 1.6 = 1/2. In other words, the brightness value is only ½ times the brightness value at the target position of 0 °. Therefore, from the above calculation result, in order to obtain an ideal color reproduction at the position of −60 ° which is the observation position of the user, the screen is irradiated from the projector with a luminance twice as high as the ideal LUT created at the position of 0 °. I understand that I have to do it. Therefore, as an example of calculating the correction table at −60 °, the L * value on all grid points of the ideal LUT is doubled, and the a * value and the b * value are kept as they are so that the color reproduction in the chromaticity direction is maintained. The LUT calculated from the value is used as a correction table at −60 ° and stored in the correction table storage unit 106.

  In addition, if the color gamut at the user observation position cannot be extended to the color gamut at the time of creating the target table due to the specifications of the projector by the above method, it is necessary to perform color space compression on the target color gamut using the predetermined method. There is. For example, in the color gamut (within gamut), mapping is performed so that the measurement values match, and with respect to the color gamut outside (gamut), mapping to a point in the color gamut where the color difference is minimum is performed by colorimetry. Perform the process. As another method, mapping accuracy may be improved by converting a color space to be mapped into a human visual space such as a Jch space and performing processing. Further, a correction table with higher accuracy may be created by performing processing such as changing the color reproduction method (mapping method) for each divided region of the color gamut. In the present embodiment, the above-described method is used as the correction table calculation method, but the calculation method may be arbitrary.

  Hereinafter, the corrected image data creation method in step S207 will be described in detail.

  The corrected image generation unit 107 uses the image data in the projection image storage unit 103, the target table in the target table storage unit 113, and the correction table in the correction table storage unit 106 obtained in step S206, and uses the corrected image data. Is generated. Then, the corrected image generation unit 107 stores the generated corrected image data in the corrected image data storage unit 108.

  Now, assuming that the image data stored in the projection image storage unit 103 is RGB data, the following description will be given. Note that the color space of the image data is not limited to RGB data. For example, the same processing is possible when the target table in the target table storage unit 113 and the correction table in the correction table storage unit 106 are described in the same data format even if they are composed of CMYK data or the like. Because there is.

  First, a device-independent spatial image data value to be projected at an observation position desired by the user is calculated using the correction table stored in the correction table storage unit 106 for the RGB values of the image data stored in the image data storage unit 103. As a calculation method, for the RGB value of each pixel (pixel) constituting the image data in the RGB color space of the image data storage unit 103, four points near the RGB value are determined from the correction table in the correction table storage unit 106. refer. Then, the corresponding Lab value may be calculated by performing tetrahedral interpolation from the four points. The Lab value is inversely interpolated from the Lab value to the RGB value using the target table in the target table storage unit 113, and a corrected RGB value for ideal color reproduction at a certain observation position is calculated. Similar processing is repeated for all pixels constituting the image. By sending the corrected image RGB data calculated by the above method to the projector 114 and projecting it onto the target screen, highly accurate color reproduction at a desired screen and observation position becomes possible.

<Second Embodiment>
Hereinafter, the second embodiment will be described with respect to the screen gain value acquisition method in step S205, the correction table creation method in step S206, and the corrected image data storage method in step S207. In the second embodiment, a corrected image can be created with high accuracy by acquiring a screen gain value for each image area corresponding to an image to be projected.

  First, the screen gain acquisition method in step S205 will be described. The projection image analysis method and patch data creation method performed in step S406, the patch measurement method performed in step S407, and the screen gain storage method performed in step 410 are shown in FIGS. 6A, 6B, 6C, 7, 7 and 10. This will be described with reference to FIG.

  In step S406, the image analysis unit 109 analyzes the projection image and creates patch data from the analysis result. The projected image is stored in the projected image storage unit 103. Image analysis is performed for each arbitrary region on the pixel data constituting the stored image. The following is an example of an analysis method in the present embodiment.

  First, region division is performed on an arbitrary number of images. In the present embodiment, as shown in FIG. 6A, the vertical direction and the horizontal direction are each equally divided into four to be divided into a total of 16 regions. For convenience, the coordinate points X0 to X4 are assigned to the division points in the horizontal direction, and the coordinate points Y0 to Y4 are assigned to the division points in the vertical direction, for convenience. Further, as shown in FIG. 6A, each area is numbered in order from the upper left to T1, T2,..., T16.

  Subsequently, patch data is created for each of the divided areas. The pixel data included in each area divided by the above method is analyzed. The divided areas are expressed as coordinates of the upper left corner and coordinates of the lower right corner of each area, that is, (coordinate points of the upper left corner, coordinate points of the lower right corner). Therefore, as a notation example, T1 = ((X0, Y0), (X1, Y1)).

  The pixel data included in the divided region T1 is analyzed. The included pixel data is data included in the coordinates from (X0, Y0) to (X1, Y1), that is, the range from X0 to X1 in the horizontal direction and the range from Y0 to Y1 in the vertical direction. In the pixel data included in the range, as a result of the histogram analysis, the pixel data included most is calculated as patch data in the region. Further, an average value of all pixel data included in the above range may be defined as patch data in each divided area. That is, the method for calculating the patch data in each divided region may be any method. The calculated patch data is stored in the patch data storage unit 110 by any method described above.

  In step S407, the screen gain value for each divided area is acquired by measuring the patch data created in step S406. In the second embodiment, the patch data created in all 16 areas up to the divided areas T1, T2,..., T16 are displayed in the divided areas and measured. Further, the measurement is performed according to a desired angle for obtaining the screen gain value. Assume that the screen gain value to be acquired is in the range of −60 ° to 60 °. In the range of −60 ° to 60 °, the observation position (angle) is shifted, and the luminance value at each position is acquired. −60 ° is an angle moved 60 ° counterclockwise when the vertical direction to the screen is 0 °. One 60 ° is defined as an angle that is moved 60 ° clockwise when the direction perpendicular to the screen is 0 ° (see FIG. 7). In this proposal, let Tcd be the luminance obtained when a certain amount of light is applied under the environment of the complete diffuser.

First, it is measured from −60 ° which is the lower limit of the measurement range. First, a projector is installed at a position perpendicular to the screen. The distance between the screen and the projector is a distance desired by the user. Subsequently, when the position connecting the projector installation position and the screen center point is set to 0 °, the measuring device is installed at an angle moved 60 ° counterclockwise on the same arc. Measurement is performed at the above position. The measurement method shall be in accordance with the usage method of the measuring equipment to be used. Measurement is performed in order from the divided region T1. When acquiring the screen gain value for the divided area T1, the patch calculated from the pixel data included in the divided area T1 in step S406 within the area of T1 ((X0, Y0), (X1, Y1)). Display and measure. Now, _assume that the luminance value obtained when the patch in the divided region T1 is measured is Y- _60T1cd . As the screen gain value, the luminance value T as a reference obtained when a constant light is applied to the complete diffuser plate under the same conditions is set to “1”. Then, the gain value at the target position is represented by the ratio of the measured luminance value at that position to the reference value. For example, the screen gain value at −60 ° can be expressed as Y _-60T1 / T = N _-60T1 . Similarly, in each region, the screen gain value in each observation position and each divided region is calculated by performing measurement by a predetermined method at observation positions (angles) from −60 ° to 60 °. The calculated screen gain value is associated with each observation position and each divided region, and is stored in the screen gain storage unit 112 in the format shown in FIG. 6C.

  Next, the correction table creation method in step S206 using the screen gain value obtained in step S205 will be described.

  A color conversion table stored in the target table storage unit 113 and capable of reproducing an ideal color; observation position (angle) information in the observation position information storage unit 104 such as a position at which the user observes the screen; And the correction table in each divided area is calculated using the screen gain value acquired for each divided area of the screen described in step 205. The target table in the target table storage unit 113 uses a predetermined projector used by the user, and is perpendicular to the screen (at a position of 0 °) and projected on the screen under a condition projected onto the predetermined screen used by the user. Assume that a LookUpTable (hereinafter referred to as an ideal LUT) from a device-dependent space to a device-independent space that can be reproduced by an ideal color obtained by measuring the center position is stored. The ideal LUT has a data structure as shown in FIG. 10 that describes the correspondence between the color coordinate data of the grid points in the RGB color space and the coordinate values of the L * a * b * color space reproduced by the grid points. Composed. The R / G / B value step is described at the head of the data structure, and thereafter, the color coordinate L * value, a * value, and b * value corresponding to each grid point are in the order of R, G, and B. Nested with This data structure is schematically represented in the RGB color space as shown in FIG. In the second embodiment, the description will be made on the assumption that the target table is in the LUT format. However, a relational expression indicating an ideal output characteristic may be stored, and the table format It does not matter.

From the above conditions, a color correction table for each divided area of the screen is calculated. First, a correction table for the divided region T1 is created. Now, it is assumed that the screen gain value of the divided region T1 is acquired in the range shown in FIG. 6C from the observation position −60 ° to 60 °. The screen gain value at an arbitrary observation position input by the user at 303 is calculated. The observation position information in the observation position information storage unit 104 is assumed to be “−55 °” and will be described below. As a calculation method of the screen gain value of −55 °, the screen gain value is calculated from N- _60T1 which is a −60 ° screen gain value and N− _50T1 which is a screen gain value of −50 °. Since −55 ° is an intermediate point between −60 ° and −50 °, the screen gain value is also calculated as an average value of the screen gain values obtained at both angles (linear interpolation calculation). When a screen gain value of −55 ° in the T1 region is defined as N _−55T1 , N _−55T1 = (N _−60T1 + N _−50T1 ) × _½ is calculated. Now, the above method has been shown as one calculation example. However, the observation position designated by the user and the screen gain value calculation method for each image division region at the observation position may be any method. . The same applies to the first embodiment described above.

Subsequently, a correction table in the divided region T1 is calculated based on the calculation result and the ideal LUT in the target table storage unit 113 created in a user environment capable of reproducing an ideal color. It is assumed that the ideal LUT has been created using a projector and a screen that the user uses in the current image projection environment. Assume that the screen gain value at the time of creating the ideal LUT is R. Assuming that the user observation position is −55 °, the screen gain value in the divided region T1 at the above position is N _−55T1 . On the other hand, since the target screen gain value is R, in order to realize ideal color reproduction at −55 °, it is necessary to perform irradiation from the projector with a luminance value multiplied by a constant R / N _−55T1. Recognize. Therefore, as an example of calculating an optimal color correction table in the user's observation position of −55 ° and the T1 region, L * values on all lattice points of the ideal LUT are multiplied by a constant R / N _−55T1 to _obtain chromaticity. In order to maintain color reproduction in the direction, the LUT calculated from the values of the a * value and the b * value as they are is used as a correction table at the observation position −55 ° and the divided region T1, and is stored in the correction table storage unit 106. Subsequently, in the T2 to T16 areas, the same processing is performed using the screen gain information associated with each area, and the correction table for each divided area is stored in the correction table storage unit 106. In the second embodiment, the above-described method is used as the correction table calculation method. However, the calculation method may be arbitrary.

  Next, the corrected image data creation method in step S207 will be described below. Using the correction table information calculated in step S206, image data desired by the user and an optimal projection image at the observation position are created. The corrected image data is processed and created for each divided area. First, corrected image data in the divided region T1 is created. With respect to the pixel data included in the divided area T1, a corrected image is created using the correction table of the divided area T1. The creation method is based on the method described in the first embodiment. Note that the correction data creation method is merely an example, and it is needless to say that an arbitrary method may be used. By the above method, the same processing is performed in all divided regions (regions T1 to T16 in the present embodiment), and corrected image data is created and stored in the corrected image data storage unit 108.

  When the divided regions are adjacent to each other, a defect (gap due to a difference in correction) may occur in the color reproduction of the pixel data of the portion where the divided regions are adjacent due to the difference in the screen gain value for each region. The correction method at this time will be described with reference to FIG.

  In order to simplify the description, it is assumed that the image is divided into four regions as shown in FIG. For the divided area S1, a correction table corresponding to S1 is referred to, and a corrected image is created. For the divided region S2 adjacent to S1, a correction table corresponding to S2 is referred to, and a corrected image is created. However, if there is a color reproduction gap in the adjacent areas of S1 and S2 due to the difference between the correction tables in both areas S1 and S2, an intermediate area such as R1 is defined between the adjacent areas, and the intermediate correction table is Apply the process that applies. The intermediate correction table may be created from the average value of the correction table in the S1 area and the correction table in the S2 area, for example. The method for creating the intermediate correction table may be any method as long as it is a means for performing smoothing (smoothing). The correction method for the intermediate correction region (in the drawing, the regions R1, R2, R3, and R4 in the drawing) using the intermediate correction table is the same as the correction image data creation method of the first embodiment. Further, in the region R5 where all of the divided regions S1 to S4 in FIG. 12 are adjacent, the correction table in R5 is calculated from the average value of the four correction tables corresponding to the S1, S2, S3, and S4 regions. To do. Calculation of corrected image data using the calculated correction table may be performed according to the created correction table.

<Third Embodiment>
In general, the horizontal length of the image projected on the screen on the screen is larger than the vertical length. Therefore, the influence of the viewpoint angle (pan angle) in the vertical direction is small. In this sense, the first and second embodiments can sufficiently improve the image quality of the projected image. However, if the size of the screen is sufficiently large or the distance between the screen and the viewer is small, the difference in angle between the viewer's viewpoint with respect to each screen surface at the left and right ends of the projected image cannot be ignored. Become. The same applies to the upper and lower ends of the screen.

  Therefore, in order to further improve the image quality in the first and second embodiments, it is desirable to create a correction table in consideration of such points.

For this, it would be good to have the following information:
1. Projector and screen positions, and the size of the projected area on the screen (horizontal and vertical lengths)
2. Viewer's viewpoint position, that is, an angle on a horizontal plane passing through the center of the screen (pan angle = an angle described in the first and second embodiments), an angle on a vertical plane passing through the center of the screen (tilt angle)), Distance from the center position of the screen to the viewpoint position The moving plane of the measuring machine when measuring is the same height as the viewer's line of sight, and the two-dimensional projection range on the screen is measured. That's fine. Note that according to the third embodiment, the correction table to be created has a capacity sufficient to perform independent conversion for each pixel. However, if a certain degree of accuracy is sufficient, it may be created for each of a plurality of regions as in the second embodiment.

  The projector projection image creation method using the projector and screen in the first, second, and third embodiments has been described above. As can be understood from the above description, the type, model, manufacturer, and the like of the projector and screen to be used. Does not matter. Further, the screen to be used can be processed in the same manner for any material as long as it is a projection surface (wall, ceiling, etc.) capable of acquiring characteristic information by a desired method. In the first and second embodiments, the screen gain is used as the value indicating the characteristic information of the projection plane. However, the screen gain is not limited as long as the characteristic information of the projection plane is indicated. It is assumed that the same processing can be performed using arbitrary information.

  In the embodiment, hardware such as a projector, an interface for outputting image data to the projector, and a screen is used, but the processing itself is realized by an application program executed on a personal computer. Therefore, it is clear that the present invention also includes a computer program. Further, the computer program is usually stored in a computer-readable storage medium such as a CD-ROM, and can be executed by setting it in a reading device (CD-ROM drive) of the computer and copying or installing it in the system. become. Therefore, it is obvious that the present invention includes such a computer-readable storage medium as its category.

1 is a block configuration diagram of an image processing system in an embodiment. It is a flowchart which shows the process sequence of the projector projection image creation process in embodiment. It is a figure which shows the user interface of the projector projection image creation application in embodiment. It is a flowchart which shows the detailed process regarding the screen gain acquisition method in step S205 of FIG. FIG. 5 is a schematic diagram showing a histogram analysis method of image analysis processing in the patch data creation processing of FIG. 4. It is a schematic diagram which shows the area | region dividing method of the other image analysis process in the patch data creation process of FIG. It is a figure which shows the relationship between the division | segmentation of an image, and the patch data of each division area. It is a figure which shows the storage state of the screen gain value in each division area. It is a figure which shows the measuring method of the patch data in embodiment. It is a figure which shows the storage format of a screen gain value. It is a figure which shows the storage format of the screen gain value information matched with the screen raw material obtained by the measurement. It is a figure which shows the data structure of a target table. It is a schematic diagram showing RGB color space. It is the schematic diagram which showed the part adjacent between a division area and the said area | region. It is a figure which shows the example of the screen gain value for every screen raw material.

Claims (9)

An image processing apparatus having projection means for projecting an image on a projection screen,
Position information input means for inputting position information for specifying the observer's viewpoint direction with respect to the projection screen;
Characteristic information input means for inputting information indicating display characteristics of each viewpoint direction with respect to the projection screen;
Correction table calculation means for calculating a correction table for correcting image data to be projected based on information input from each of the position information input means and characteristic information input means;
An image processing apparatus comprising: correction means for correcting image data to be output to the projection means according to the correction table calculated by the correction table calculation means.   The image processing apparatus according to claim 1, wherein the position information is an angle of the observer with respect to a surface of the projection screen. The characteristic information input means includes
Storage means for storing a plurality of predefined types of projection screens, and characteristic information indicating characteristics of each type of display in each viewpoint direction;
Display means for selectively displaying the types of the plurality of projection screens stored in the storage means;
2. The image according to claim 1, wherein characteristic information corresponding to the type of the selected projection screen is input as information indicating display characteristics of each viewpoint direction of the projection screen projected by the projection unit. Processing equipment. The display means further displays an arbitrary type of projection screen other than those stored in the storage means as one of selection candidates,
When the arbitrary type of projection screen is selected, a file storing the characteristic information of the projection screen projected by the projection unit is designated, or the characteristic of the projection screen projected by the projection unit is optically detected. The image processing apparatus according to claim 3, further comprising: a first selection unit that selects whether to measure using the image. A first measuring unit that calculates characteristic information indicating characteristics of display in each of the viewpoint directions of the projection screen when the first selecting unit selects the measurement using the optical detection unit; A second selection means for selecting one of the two measurement means;
The first measuring means includes
Analyzing the target image data to be output to the projection unit, and generating a patch image for detection by the optical detection unit;
By outputting the generated patch image to the projection unit, the patch image is projected onto the projection screen, and the patch image projected onto the projection screen is detected by the optical detection unit from a plurality of different viewpoint directions. By providing means for calculating the characteristics for each viewpoint direction,
The second measuring means includes
5. The apparatus according to claim 4, further comprising means for calculating characteristics of each viewpoint direction by detecting the projection screen from a plurality of different viewpoint directions by the optical detection means without projection by the projection means. The image processing apparatus described.   The patch image generation unit divides target image data to be output to the projection unit into a plurality of preset regions, calculates representative pixel values for each divided region, and calculates each representative pixel value of each region. The image processing apparatus according to claim 5, wherein the image processing apparatus sets the pixel value of the patch image. A method for controlling an image processing apparatus having a projecting means for projecting an image onto a projection screen, wherein the position information input step inputs position information for specifying the observer's viewpoint direction with respect to the projection screen;
A characteristic information input step for inputting information indicating characteristics of display in each viewpoint direction with respect to the projection screen;
A correction table calculating step for calculating a correction table for correcting the image data to be projected based on the information input from each of the position information input step and the characteristic information input step;
And a correction step of correcting the target image data to be output to the projection means in accordance with the correction table calculated in the correction table calculation step.   A computer program that causes a computer having a projecting unit that projects an image on a projection screen to read and execute the computer to function as the image processing apparatus according to any one of claims 1 to 6.   A computer-readable storage medium storing the computer program according to claim 8.

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