Image projection device, image projection method, and program

Abstract

To provide an image projection device, an image projection method, and a program capable of preventing focus deviation from being recognized easily while suppressing complication of a structure.SOLUTION: An image projection device for projecting an image from a projection optical system includes: an acquisition section for acquiring image data; a classification section for classifying image patterns shown by the image data acquired by the acquisition section; a detection section for detecting whether the pattern classified by the classification section is switched or not; and a switching section for switching a gamma curve applied to the image data to a gamma curve corresponding to the pattern when the detection section detects switching of the pattern.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an image projection device, an image projection method, and a program. [Background technology]

[0002] The lenses of the projection optical system mounted on an image projection device (projector) expand or contract depending on the temperature, although to different degrees. Such expansion or contraction of the lenses of the projection optical system is prominent in an optical system that employs a reflecting mirror to shorten the focal length. That is, when a bright image is projected and displayed, the lens (the lens and the reflecting mirror in case of using a reflecting mirror) constituting the projection optical system expands because a large amount of light passes through it. On the other hand, when a dark image is projected and displayed, the lens (the lens and the reflecting mirror in case of using a reflecting mirror) of the projection optical system expands less because a small amount of light passes through it, and it appears to have contracted compared to when it expanded. When the lens expands or contracts due to the temperature change in this way, the focal length of the lens changes. This phenomenon is called temperature drift (hereinafter simply referred to as drift). This drift causes the focal position of the lens to change, which is recognized as being out of focus in the image projected on the screen.

[0003] In the design of optical systems, this drift may be assumed, but it is difficult to completely eliminate drift within the range of lens use. Optical designers attempt to minimize this drift as much as possible, but reducing it to a completely negligible level would result in a lens configuration that is quite expensive and would be unsuitable for use in the projection optical system of a general-purpose projector. For this reason, the reality is that lens designs must allow for a certain degree of drift. In addition, there is a demand for simplification of adjustments during the manufacturing process, so there is also a demand for simplification of lens system designs.

[0004] Furthermore, as a technology for dealing with the above-mentioned focus shift, a technology has been disclosed in which an image projected by a projector onto a screen is captured by a camera, the focus shift is detected, the result is fed back to the projector, and the electric focus installed in the projector is controlled to stably maintain the focus quality of the image projected onto the screen (for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 requires the projection optical system to be equipped with an electric focus mechanism and an imaging device for capturing an image of the screen surface, which results in a complex structure and correspondingly high costs.

[0006] The present invention has been made in consideration of the above, and also aims to provide an image projection device, an image projection method, and a program that can make focus shift less noticeable while suppressing structural complexity. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the present invention provides an image projection device that projects an image from a projection optical system, and is characterized in that it comprises an acquisition unit that acquires image data, a classification unit that classifies the pattern of an image indicated by the image data acquired by the acquisition unit, a detection unit that detects whether the pattern classified by the classification unit has changed, and a switching unit that switches the gamma curve applied to the image data to a gamma curve corresponding to the pattern when the detection unit detects that the pattern has changed. Effect of the Invention

[0008] According to the present invention, it is possible to make defocus difficult to notice while suppressing the complexity of the structure. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of a schematic overall structure of an image projection device according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a schematic structure of an illumination device of the image projection device according to the embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a hardware configuration of the image projection device according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of a functional block configuration of the image projection device according to the embodiment. [Diagram 5] FIG. 5 is a graph showing an example of frequency characteristics of a continuous type image. [Figure 6] FIG. 6 is a graph showing an example of frequency characteristics of a discrete image. [Figure 7] FIG. 7 is a diagram showing an example of a gamma curve. [Figure 8] FIG. 8 is a flowchart showing an example of the flow of the operation of the image projection device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the image projection device, image projection method, and program according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and the components in the following embodiments include those that a person skilled in the art can easily conceive, those that are substantially the same, and those that are within the scope of what is called equivalent. Furthermore, various omissions, substitutions, modifications, and combinations of the components can be made without departing from the spirit of the following embodiments.

[0011] (General structure of image projection device) Fig. 1 is a diagram showing an example of a schematic overall structure of an image projection device according to an embodiment. Fig. 2 is a diagram showing an example of a schematic structure of an illumination device of an image projection device according to an embodiment. An overview of the structure of an image projection device 10 according to this embodiment will be described with reference to Figs. 1 and 2. Note that in Figs. 1 and 2, the X direction, Y direction, and Z direction are perpendicular to each other, the X direction and the Y direction indicate the horizontal direction, and the Z direction is indicated as the vertical direction.

[0012] 1 is a device that projects an image represented by image data such as a moving image or a still image onto a projection surface W. The image projection device 10 includes, within a housing 11, an illumination device 12, a rod integrator 13, an illumination optical system 14, a DMD (Digital Micromirror Device) 15, and a projection optical system 16.

[0013] The lighting device 12 is a device that emits illumination light. The structure of the lighting device 12 will be described in detail later.

[0014] Rod integrator 13 is a rod-shaped glass member, and is an optical element that homogenizes the illumination light incident from lighting device 12 by internally reflecting the illumination light multiple times. Specifically, rod integrator 13 outputs, as illumination light, homogenized illuminance and light intensity distribution of two systems of light F1 and F2 combined by prism 110 described later.

[0015] The optical element for homogenizing the light is not limited to the rod integrator 13, but may be, for example, a prismatic light tunnel having mirrors bonded to four sides, or a fly-eye lens.

[0016] The illumination optical system 14 is an optical system for guiding the illumination light output from the rod integrator 13 to the DMD 15. The illumination optical system 14 is composed of optical elements including lenses and mirrors.

[0017] The DMD 15 is a component that generates an image by using micromirrors arranged on its surface to reflect illumination light guided by the illumination optical system 14. Note that instead of the DMD 15, a transmissive liquid crystal element or a reflective liquid crystal element may also be used.

[0018] The projection optical system 16 is disposed downstream of the DMD 15 in the optical path, and is an optical system that enlarges and projects light representing an image generated by the DMD 15 as projection light onto a projection surface W, which is a screen. The projection optical system 16 is composed of optical elements including lenses and mirrors.

[0019] Next, the structure of the illumination device 12 will be described in detail with reference to Fig. 2. Fig. 2 shows a schematic plan view of the image projection device 10 as seen from above.

[0020] As shown in FIG. 2, the illumination device 12 includes a first light source unit LS1, a second light source unit LS2, a prism 110, and a color wheel 111.

[0021] The first light source unit LS1 is a unit that irradiates the prism 110 with light F1, which is obtained by optically processing excitation light irradiated from a light source using various internal optical elements. As shown in Fig. 2, the first light source unit LS1 includes an LED (Light Emitting Diode) light source 101a, a collimator lens 102a, a light source optical system 103a, a condensing element 104a, a microlens array 105a, a dichroic mirror 106a, a first condensing optical system 107a, a phosphor wheel 108a, and a second condensing optical system 109a.

[0022] The LED light source 101a is a light source component that emits excitation light using an LED as a light source. Note that the LED light source 101a is not limited to an LED, and may be, for example, a multi-chip laser diode unit in which a plurality of light-emitting parts are arranged in a one-dimensional or two-dimensional array.

[0023] The collimator lens 102a is disposed opposite the light emitting side of the LED light source 101a, and is an optical member that converts the excitation light emitted from the LED light source 101a into parallel light.

[0024] The light source optical system 103a is an optical member that collects the excitation light that has been converted into parallel light by the collimator lens 102a.

[0025] The light-collecting element 104a is a lens member that has negative power and is disposed after the light-source optical system 103a, and that reduces the focusing property of the excitation light focused by the light-source optical system 103a.

[0026] The microlens array 105a is a light profile adjustment element that homogenizes the light intensity distribution of the irradiation spot of the excitation light that is irradiated at a desired position on the downstream phosphor wheel 108a.

[0027] The dichroic mirror 106a is a reflecting member that reflects only light of a specific wavelength from the excitation light beam that has passed through the microlens array 105a. Note that a reflective diffractive optical element (DOE) may be used instead of the dichroic mirror 106a.

[0028] The first light collecting optical system 107a is an optical member that causes the excitation light reflected by the dichroic mirror 106a to form an irradiation spot at a desired position on the phosphor wheel 108a. As described later, the light reflected by the phosphor wheel 108a passes through the first light collecting optical system 107a again and travels to the second light collecting optical system 109a.

[0029] The phosphor wheel 108a is a disk-shaped wavelength conversion element that rotates at high speed by a drive motor. The phosphor wheel 108a has a phosphor region that is a wavelength conversion region coated with phosphor, and an excitation light reflection region that is a non-wavelength conversion region that reflects excitation light. That is, the phosphor wheel 108a rotates to switch between the phosphor region and the excitation light reflection region at the position of the above-mentioned irradiation spot. In this embodiment, blue light with a central wavelength of emission intensity of, for example, 455 [nm] can be used as the excitation light emitted from the LED light source 101a. In this case, when the excitation light reflection region is located at the position of the irradiation spot, the phosphor wheel 108a outputs blue light as it is without wavelength conversion. On the other hand, when the phosphor region is located at the position of the irradiation spot, the phosphor wheel 108a converts the wavelength into yellow or yellow-green fluorescence and outputs it.

[0030] Although the phosphor wheel 108a is described as being divided into two regions, a phosphor region and an excitation light reflection region, this is not limited to this, and the phosphor wheel 108a may have a plurality of fluorescent regions that convert to different wavelengths (for example, a fluorescent region that emits yellow light and a fluorescent region that emits green light), or may have a plurality of excitation light reflection regions.

[0031] The second light collecting optical system 109a is an optical member that collects the light that is reflected by the phosphor wheel 108a and transmitted through the first light collecting optical system 107a. The light collected by the second light collecting optical system 109a is incident on a reflecting surface 110A of a prism 110.

[0032] The second light source unit LS2 is a unit that irradiates the prism 110 with light F2, which is obtained by optically processing excitation light irradiated from a light source using various internal optical elements. As shown in Fig. 2, the second light source unit LS2 has an LED light source 101b, a collimator lens 102b, a light source optical system 103b, a condensing element 104b, a microlens array 105b, a dichroic mirror 106b, a first condensing optical system 107b, a phosphor wheel 108b, and a second condensing optical system 109b. The functions of the LED light source 101b, the collimator lens 102b, the light source optical system 103b, the condensing element 104b, the microlens array 105b, the dichroic mirror 106b, the first condensing optical system 107b, the phosphor wheel 108b, and the second condensing optical system 109b are similar to those of the LED light source 101a, the collimator lens 102a, the light source optical system 103a, the condensing element 104a, the microlens array 105a, the dichroic mirror 106a, the first condensing optical system 107a, the phosphor wheel 108a, and the second condensing optical system 109a. The light condensed by the second condensing optical system 109b is incident on the transmission surface 110B of the prism 110.

[0033] Prism 110 is a polyhedral synthesis optical element having four or more faces. Prism 110 reflects light F1 emitted from first light source unit LS1 on reflecting surface 110A, transmits light F2 emitted from second light source unit LS2 through transmitting surface 110B, synthesizes light F1 and light F2, and guides the light to rod integrator 13 as a light flux proceeding in approximately the same direction.

[0034] In addition, it is preferable that the transmitting surface 110B of the prism 110 on which the light F2 is incident is a diffusing surface. By making the transmitting surface 110B a diffusing surface, it is possible to eliminate unevenness in color and brightness of the light passing through the transmitting surface 110B. Also, instead of providing a diffusing surface on the prism 110, a separate diffusing plate may be provided to eliminate unevenness in color and brightness of the light.

[0035] In addition, the combining optical element is not limited to prism 110, but may be any optical element that can combine light irradiated from two or more light source units into light traveling in approximately the same direction and guide it to rod integrator 13.

[0036] Color wheel 111 is a disk-shaped member disposed between prism 110 and rod integrator 13, and time-divides the light combined by prism 110 into red, blue, green, and yellow. Specifically, color wheel 111 has a red region that transmits only red light, a blue region that transmits only blue light, a green region that transmits only green light, and a yellow region that transmits only yellow light, and is rotated by a motor to time-divide the light combined by prism 110 into red, blue, green, and yellow. The light time-divided by color wheel 111 enters rod integrator 13.

[0037] Color wheel 111 is controlled to rotate in synchronization with phosphor wheels 108a and 108b at the same rotation speed. For example, as described above, when light split into blue light and yellow (or yellow-green) fluorescence by phosphor wheels 108a and 108b is incident on color wheel 111, color wheel 111 is controlled to rotate so that the blue region of color wheel 111 corresponds to the excitation light reflection region of phosphor wheels 108a and 108b, and the red region, green region, and yellow region correspond to the phosphor region of phosphor wheels 108a and 108b. In this way, the red, blue, green, and yellow light time-shared by phosphor wheels 108a and 108b and color wheel 111 is homogenized by rod integrator 13 and then guided to DMD 15.

[0038] Color wheel 111 may be disposed after rod integrator 13 (on the light output side).

[0039] (Hardware configuration of image projection device) 3 is a diagram showing an example of a hardware configuration of an image projection device according to an embodiment of the present invention, the hardware configuration of an image projection device 10 according to the present embodiment will be described with reference to FIG.

[0040] 3, the image projection device 10 includes a CPU (Central Processing Unit) 801, a ROM (Read Only Memory) 802, a RAM (Random Access Memory) 803, a media I / F 807, an operation unit 808, a power switch 809, a network I / F 811, an LED drive circuit 814, an external device connection I / F 818, a fan drive circuit 819, and a cooling fan 820. The CPU 801, the ROM 802, the RAM 803, the media I / F 807, the operation unit 808, the network I / F 811, the LED drive circuit 814, the external device connection I / F 818, and the fan drive circuit 819 are electrically connected by a bus 810, which is an address bus, a data bus, or the like, so as to enable data communication between them.

[0041] The CPU 801 is a calculation device that controls the overall operation of the image projection device 10. The ROM 802 is a non-volatile storage device that stores programs used to drive the CPU 801. The RAM 803 is a volatile storage device used as a work area for the CPU 801.

[0042] The media I / F 807 is an interface circuit that controls reading and writing (storing) of data from and to a medium 806 such as a flash memory.

[0043] The operation unit 808 has various keys, buttons, LEDs, etc., and is used by the user to perform various operations other than turning on / off the power of the image projection device 10. For example, the operation unit 808 accepts instruction operations such as an operation to adjust the size of the projection image, an operation to adjust the color tone, an operation to adjust the focus, an operation to adjust the keystone, etc., and outputs the contents of the accepted operations to the CPU 801.

[0044] The power switch 809 is a switch for switching the power of the image projection device 10 ON / OFF.

[0045] The network I / F 811 is an interface circuit for performing data communication using a communication network such as the Internet.

[0046] The LED drive circuit 814 is a drive circuit that controls turning on and off the LED light sources 101a and 101b under the control of the CPU 801.

[0047] The external device connection I / F 818 is an interface circuit for connecting to an external device such as a PC (Personal Computer) and communicating control signals, image data, and the like.

[0048] The fan drive circuit 819 is connected to the CPU 801 and the cooling fan 820, and is a drive circuit for driving / stopping the cooling fan 820 based on a control signal from the CPU 801. The cooling fan 820 is a fan device that is rotated by the fan drive circuit 819 to exhaust air inside the image projection device 10 and cool the inside of the image projection device 10.

[0049] Furthermore, when the CPU 801 is supplied with power from the power source, it starts up according to a control program prestored in the ROM 802, and sends a control signal to an LED drive circuit 814 to turn on the LED light sources 101a and 101b. The CPU 801 also sends a control signal to a fan drive circuit 819 to rotate the cooling fan 820 at a predetermined rated speed. When the supply of power from the power source circuit starts, the image projection device 10 puts the DMD 15 in a state capable of displaying images, and furthermore, power is supplied from the power source circuit to various other components.

[0050] Furthermore, when the power switch 809 of the image projection device 10 is turned OFF, the power switch 809 sends a power OFF signal to the CPU 801, and when the CPU 801 detects the power OFF signal, it sends a control signal to the LED drive circuit 814 to turn off the LED light sources 101a and 101b. After that, when a predetermined time has elapsed, the CPU 801 sends a control signal to the fan drive circuit 819 to stop the cooling fan 820, and also ends its own control process, and finally sends an instruction to the power circuit to stop the supply of power from the power source.

[0051] (Configuration and operation of functional blocks of image projection device) Fig. 4 is a diagram showing an example of the configuration of functional blocks of the image projection device according to the embodiment. Fig. 5 is a graph showing an example of frequency characteristics of a continuous image. Fig. 6 is a graph showing an example of frequency characteristics of a discrete image. Fig. 7 is a diagram showing an example of a gamma curve. The configuration and operation of the functional blocks of the image projection device 10 according to the present embodiment will be described with reference to Figs. 4 to 7.

[0052] As shown in FIG. 4, the image projection device 10 includes an acquisition unit 201, a feature extraction unit 202 (extraction unit), an image type determination unit 203 (first determination unit), a brightness determination unit 204 (second determination unit), an image classification unit 205 (classification unit), an image change detection unit 206 (detection unit), a gamma curve switching unit 207 (switching unit), a projection control unit 208, and a memory unit 209.

[0053] The acquisition unit 201 is a functional unit that acquires image data via the media I / F 807 , the external device connection I / F 818 , or the network I / F 811 .

[0054] The feature extraction unit 202 is a functional unit that decomposes the signal level of the luminance value of the image data acquired by the acquisition unit 201 into frequency components and extracts them as feature amounts by performing frequency analysis or the like on the image data acquired by the acquisition unit 201. For example, when the image data acquired by the acquisition unit 201 is video data, the feature extraction unit 202 cumulatively performs frequency analysis on several frames and extracts the decomposed frequency components as feature amounts.

[0055] Here, when the frequency components of the signal level of the image data are evenly distributed over a wide frequency range, as shown in Fig. 5, it is determined to be a natural image, etc., and the image represented by such image data is referred to as a continuous type image. On the other hand, when the frequency components of the signal level of the image data are discretely scattered, as shown in Fig. 6, it is determined to be a presentation material containing a lot of text, etc., and the image represented by such image data is referred to as a discrete type image.

[0056] The image type determination unit 203 is a functional unit that determines the type of image, whether the image represented by the image data is a continuous image (first image) or a discrete image (second image), based on the frequency components of the image data extracted by the feature extraction unit 202. For example, the image type determination unit 203 may determine that the image represented by the image data is a continuous image when frequency components with a signal level equal to or greater than a predetermined threshold value exist over a predetermined frequency range, and may determine that the image represented by the image data is a discrete image when such frequency components do not exist. Note that the method of determining whether an image is a continuous image or a discrete image is not limited to the above.

[0057] The luminance determination unit 204 is a functional unit that determines whether the image indicated by the image data acquired by the acquisition unit 201 is a bright image (third image) or a dark image (fourth image). For example, the luminance determination unit 204 may calculate an APL (Average Picture Level) of the image indicated by the image data, and determine the image as a bright image if the APL is equal to or greater than a predetermined threshold, and determine the image as a dark image if the APL is less than the threshold. Note that the method of determining whether an image is bright or dark is not limited to the above.

[0058] The image classification unit 205 is a functional unit that classifies the image pattern indicated by the image data acquired by the acquisition unit 201 based on the determination results by the image type determination unit 203 and the brightness determination unit 204. Specifically, the image classification unit 205 classifies the image into one of four patterns: a continuous and bright image, a continuous and dark image, a discrete and bright image, or a discrete and dark image.

[0059] The image patterns classified by the image classification unit 205 are not limited to the above four, and may be classified into patterns other than four. For example, the image type determination unit 203 is not limited to determining whether the image is a continuous type image or a discrete type image, and may determine whether the image is one of three or more types of images based on the frequency components of the image data. The brightness determination unit 204 is not limited to determining whether the image is a bright image or a dark image, and may determine whether the image is one of three or more levels of brightness based on the APL of the image data. As a result, the image classification unit 205 may classify the image into four or more patterns. The image classification unit 205 is not limited to classifying the image pattern indicated by the image data from the determination results of both the image type determination unit 203 and the brightness determination unit 204, and may classify the image from at least one of the determination results of the image type determination unit 203 and the brightness determination unit 204.

[0060] The image change detection unit 206 is a functional unit that detects whether or not the pattern of an image classified by the image classification unit 205 has changed to a pattern different from the pattern of the image previously classified by the image classification unit 205 .

[0061] Gamma curve switching unit 207 is a functional unit that switches the gamma curve applied to image data when it is detected by image change detection unit 206 that the image pattern of the image data has been switched to another pattern. Switching the gamma curve applied to image data refers to, for example, when the image data is moving image data, switching from the gamma curve applied to the specific frame to the gamma curve corresponding to the next frame when the image pattern of a specific frame (or a group of frames) included in the moving image data is switched to a different pattern as the image pattern of the next frame (or a group of frames) of the specific frame.

[0062] A gamma curve determines the brightness of intermediate luminance levels by controlling the relationship between the input level and the output level of image data so that a displayed image (here, an image projected by the image projection device 10) changes from black to white (or white to black) in a predetermined manner. For example, a gamma curve that controls the relationship between the input level and the output level of image data so that an image of the image data appears to change from black to white at a constant change amount (i.e., linearly) when the image of the image data is displayed is an optimal gamma curve for the image projection device 10 as a display device, and is represented, for example, by the gamma curve GC2 shown in FIG. 7. On the other hand, a gamma curve that controls the relationship between the input level and the output level of image data so that an overall image appears brighter by displaying intermediate luminance levels higher than the gamma curve GC2 is represented, for example, by the gamma curve GC1 shown in FIG. 7. Also, a gamma curve that controls the relationship between the input level and the output level of image data so that an overall image appears darker by displaying intermediate luminance levels lower than the gamma curve GC2 is represented, for example, by the gamma curve GC3 shown in FIG. 7. That is, by switching the gamma data applied to the image data, it is possible to change the display mode of the image of the image data. 7, in any of the gamma curves, the luminance levels (brightness) of black and white are not changed, and only intermediate luminance levels are changed. Note that in this embodiment, it is assumed that data of the gamma curves GC1 to GC3 are stored in the storage unit 209.

[0063] Here, it is determined that a continuous image such as a natural image is less likely to be perceived as out of focus because various frequency components are mixed in the image. Therefore, when the image change detection unit 206 detects that the image pattern of the image data has switched to a continuous image pattern, the gamma curve switching unit 207 switches to apply the gamma curve GC2 optimal for the display device to the image data.

[0064] On the other hand, discrete images such as presentation materials often display character strings and are expected to be read, so it is determined that the degree of focus deviation is very high. In addition, since the drift of the lens of the projection optical system 16 depends on the amount of light transmitted (i.e., the brightness of the image), the degree of drift becomes noticeable when the amount of light changes suddenly. Therefore, since the occurrence of drift itself cannot be avoided, in this embodiment, the elapsed time until the drift appears is controlled to make the focus deviation difficult to recognize. Specifically, when the image change detection unit 206 detects that the image pattern of the image data has switched to a discrete image and a dark image pattern, the gamma curve switching unit 207 switches to apply a gamma curve GC1 that displays intermediate luminance levels higher than the gamma curve GC2 to the image data. In addition, when the image change detection unit 206 detects that the image pattern of the image data has switched to a discrete image and a bright image pattern, the gamma curve switching unit 207 switches to apply a gamma curve GC3 that displays intermediate luminance levels lower than the gamma curve GC2 to the image data. This makes it possible to smooth out sudden changes in brightness of the image, which in turn makes it possible to smooth out the occurrence of drift, making it possible to make focus deviation less noticeable.

[0065] The gamma curve switching unit 207 is not limited to switching to one of the three gamma curves GC1 to GC3, but may switch to one of four or more gamma curves depending on the image pattern detected by the image change detection unit 206.

[0066] The projection control unit 208 is a functional unit that applies the gamma curve switched by the gamma curve switching unit 207 to the image data acquired by the acquisition unit 201, controls the DMD 15 to generate an image, and projects the image from the projection optical system 16. Specifically, the projection control unit 208 may refer to the storage unit 209, read out data of the gamma curve switched by the gamma curve switching unit 207, and apply the data to the image data.

[0067] The storage unit 209 is a functional unit that stores gamma curve data, image data acquired by the acquisition unit 201, etc. The storage unit 209 is realized by the ROM 802 or the RAM 803 shown in FIG.

[0068] The above-mentioned acquisition unit 201, feature amount extraction unit 202, image type determination unit 203, luminance determination unit 204, image classification unit 205, image change detection unit 206, gamma curve switching unit 207, and projection control unit 208 are realized by, for example, executing a program by CPU 801 shown in Fig. 3. Note that at least a part of the acquisition unit 201, feature amount extraction unit 202, image type determination unit 203, luminance determination unit 204, image classification unit 205, image change detection unit 206, gamma curve switching unit 207, and projection control unit 208 may be realized by a hardware circuit such as a field-programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

[0069] Note that the functions of each functional unit of the image projection device 10 shown in FIG. 4 are conceptually shown, and the configuration is not limited to this. In other words, each functional unit of the image projection device 10 does not need to be configured as a clear software module as the block shown in FIG. 4, and the function of each functional unit as a whole may be realized by executing a program in the image projection device 10. For example, multiple functional units illustrated as independent functional units in the image projection device 10 shown in FIG. 4 may be configured as one functional unit. On the other hand, the function of one functional unit in the image projection device 10 shown in FIG. 4 may be divided into multiple functions and configured as multiple functional units.

[0070] (Overall operation of the image projection device) 8 is a flowchart showing an example of the flow of operations of the image projection device according to the embodiment. The flow of the entire operations of the image projection device 10 according to the present embodiment will be described with reference to FIG.

[0071] <Step S11> The acquisition unit 201 of the image projection device 10 acquires image data via the media I / F 807, the external device connection I / F 818, or the network I / F 811. Then, the process proceeds to step S12 and step S14.

[0072] <Step S12> The feature extraction unit 202 of the image projection device 10 extracts the feature by decomposing the signal level of the luminance value of the image data acquired by the acquisition unit 201 into frequency components by frequency analysis or the like on the image data. Then, the process proceeds to step S13.

[0073] <Step S13> The image type determination unit 203 of the image projection device 10 determines, based on the frequency components of the image data extracted by the feature extraction unit 202, whether the image represented by the image data is a continuous image or a discrete image.

[0074] <Step S14> The brightness determination unit 204 of the image projection device 10 determines whether the image indicated by the image data acquired by the acquisition unit 201 is a bright image or a dark image.

[0075] When the processes of steps S13 and S14 described above are completed, the process proceeds to step S15.

[0076] <Step S15> The image classification unit 205 of the image projection device 10 classifies the image indicated by the image data acquired by the acquisition unit 201 based on the determination results by the image type determination unit 203 and the brightness determination unit 204. Specifically, the image classification unit 205 classifies the image into one of the four patterns: a continuous image and a bright image, a continuous image and a dark image, a discrete image and a bright image, or a discrete image and a dark image. Then, the process proceeds to step S16.

[0077] <Step S16> The image change detection unit 206 of the image projection device 10 detects whether the image pattern classified by the image classification unit 205 has changed to a different pattern from the image pattern previously classified by the image classification unit 205. If the image change detection unit 206 detects a change (switch) in the image pattern (step S16: Yes), the process proceeds to step S17, and if not (step S16: No), the operation ends.

[0078] <Step S17> The gamma curve switching unit 207 of the image projection device 10 switches the gamma curve corresponding to the image pattern in which the image change detection unit 206 detects the change to be applied to the image data acquired by the acquisition unit 201. Specifically, when the image change detection unit 206 detects that the image pattern of the image data has changed to a continuous image pattern, the gamma curve switching unit 207 switches the gamma curve GC2 that is optimal for the display device to be applied to the image data. When the image change detection unit 206 detects that the image pattern of the image data has changed to a discrete image and a dark image pattern, the gamma curve switching unit 207 switches the gamma curve GC1 that displays intermediate luminance levels higher than the gamma curve GC2 to be applied to the image data. When the image change detection unit 206 detects that the image pattern of the image data has changed to a discrete image and a bright image pattern, the gamma curve switching unit 207 switches the gamma curve GC3 that displays intermediate luminance levels lower than the gamma curve GC2 to be applied to the image data. Then, the projection control unit 208 of the image projector 10 applies the gamma curve switched by the gamma curve switching unit 207 to the image data acquired by the acquisition unit 201, controls the DMD 15 to generate an image, and projects the image from the projection optical system 16. Then, the operation ends.

[0079] The above-mentioned steps S11 to S17 are repeatedly executed. Note that, when the entire image data is acquired by the acquisition unit 201 in step S11 and stored in the storage unit 209, steps S12 to S17 may be repeatedly executed while referring to the image data stored in the storage unit 209.

[0080] As described above, in the image projection device 10 according to this embodiment, the acquisition unit 201 acquires image data, the image classification unit 205 classifies the image pattern indicated by the image data acquired by the acquisition unit 201, the image change detection unit 206 detects whether the pattern classified by the image classification unit 205 has been switched, and the gamma curve switching unit 207 switches the gamma curve applied to the image data to a gamma curve corresponding to the pattern when the image change detection unit 206 detects that the pattern has been switched. This eliminates the need to mount a separate structure or device such as a focus mechanism or imaging device to deal with focus shifts, thereby making it possible to suppress structural complication and make focus shifts less noticeable.

[0081] In the above-mentioned embodiment, when at least one of the functional units of the image projection device 10 is realized by executing a program, the program is provided by being incorporated in a ROM or the like in advance. In the above-mentioned embodiment, the program executed by the image projection device 10 may be provided by being recorded in a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), a flexible disk (FD), a CD-R (Compact Disk-Recordable), or a DVD (Digital Versatile Disc) in an installable or executable format. In the above-mentioned embodiment, the program executed by the image projection device 10 may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. In the above-mentioned embodiment, the program executed by the image projection device 10 may be provided or distributed via a network such as the Internet. In the above-mentioned embodiment, the program executed by the image projection device 10 has a modular configuration including at least one of the functional units described above, and as actual hardware, the CPU 801 reads out the program from the above-mentioned storage device (for example, the ROM 802, the medium 806, etc.) and executes it, so that the above-mentioned functional units are loaded onto the main storage device (RAM 803) and generated.

[0082] The aspects of the present invention are as follows. <1> An image projection device that projects an image from a projection optical system, An acquisition unit that acquires image data; a classification unit that classifies an image pattern represented by the image data acquired by the acquisition unit; a detection unit that detects whether the pattern classified by the classification unit has been changed; a switching unit that switches a gamma curve to be applied to the image data to a gamma curve corresponding to the pattern when the detection unit detects that the pattern has been switched; The image projection device includes: <2> The projection control unit applies the gamma curve switched by the switching unit to the image data, and projects an image from the projection optical system. <1> The image projection device according to the present invention is <3> A storage unit that stores data of a plurality of the gamma curves, The projection control unit reads out data corresponding to the gamma curve switched by the switching unit from the storage unit and applies the data to the image data. <2> The image projection device according to the present invention is <4> an extracting unit that extracts a predetermined feature amount from the image data acquired by the acquiring unit; a first determination unit that determines a type of an image represented by the image data from the feature amount extracted by the extraction unit; Further equipped with The classification unit classifies a pattern of an image represented by the image data based on at least a determination result of the first determination unit. <1> ~ <3> The present invention relates to an image projection device according to any one of the above. <5> The extraction unit decomposes a luminance value of the image data acquired by the acquisition unit into frequency components and extracts them as the feature amount, The first determination unit determines, from the frequency components extracted by the extraction unit, whether an image represented by the image data is at least a first image in which the frequency components exist continuously in a predetermined frequency range, or a second image in which the frequency components exist discretely. <4> The image projection device according to the present invention is <6> a second determination unit that determines whether the image indicated by the image data acquired by the acquisition unit is at least a third image having a predetermined brightness or more, or a fourth image darker than the third image, The classification unit classifies a pattern of an image represented by the image data based on at least a determination result of the second determination unit. <1> ~ <5> The present invention relates to an image projection device according to any one of the above. <7> An image projection method for projecting an image from a projection optical system, comprising: An acquisition step of acquiring image data; A classification step of classifying an image pattern represented by the acquired image data; a detection step of detecting whether the classified pattern has been switched; a switching step of switching a gamma curve to be applied to the image data to a gamma curve corresponding to the pattern when it is detected that the pattern has been switched; The image projection method includes: <8> A computer that is an image projection device that projects an image from a projection optical system, An acquisition step of acquiring image data; A classification step of classifying an image pattern represented by the acquired image data; a detection step of detecting whether the classified pattern has been switched; a switching step of switching a gamma curve to be applied to the image data to a gamma curve corresponding to the pattern when it is detected that the pattern has been switched; This is a program for executing the above. [Explanation of symbols]

[0083] 10 Image projection device 11. Cabinet 12 Lighting equipment 13 Rod Integrator 14 Illumination optical system 15 DMD 16 Projection optical system 101a, 101b LED light source 102a, 102b Collimator lenses 103a, 103b Light source optical system 104a, 104b Light collecting element 105a, 105b Microlens array 106a, 106b Dichroic mirror 107a, 107b First light collecting optical system 108a, 108b Phosphor wheel 109a, 109b Second light collecting optical system 110 Prism 110A reflective surface 110B Transparent surface 111 Color Wheel 201 Acquisition Department 202 Feature Extraction Unit 203 Image type determination unit 204 Luminance judgment unit 205 Image Classification Unit 206 Image change detection unit 207 Gamma curve switching section 208 Projection control unit 209 Memory section 801 CPU 802 ROM 803 RAM 806 Media 807 Media Interface 808 Control unit 809 Power Switch 810 Bus 811 Network Interface 814 LED driving circuit 818 External device connection interface 819 Fan drive circuit 820 Cooling Fan F1, F2 light GC1~GC3 Gamma Curve LS1 First light source unit LS2 Second light source unit W projection plane [Prior art documents] [Patent documents]

[0084] [Patent Document 1] JP 2006-313201 A

Claims

1. An image projection device that projects an image from a projection optical system, An acquisition unit that acquires image data; a classification unit that classifies an image pattern represented by the image data acquired by the acquisition unit; a detection unit that detects whether the pattern classified by the classification unit has been changed; a switching unit that switches a gamma curve to be applied to the image data to a gamma curve corresponding to the pattern when the detection unit detects that the pattern has been switched; An image projection device comprising:

2. The image projection device according to claim 1 , further comprising a projection control unit that applies the gamma curve switched by the switching unit to the image data and projects an image from the projection optical system.

3. A storage unit that stores data of a plurality of the gamma curves, The image projection device according to claim 2 , wherein the projection control unit reads out data corresponding to the gamma curve switched by the switching unit from the storage unit and applies the data to the image data.

4. an extracting unit that extracts a predetermined feature amount from the image data acquired by the acquiring unit; a first determination unit that determines a type of an image represented by the image data from the feature amount extracted by the extraction unit; Further equipped with 4. The image projection device according to claim 1, wherein the classification section classifies the pattern of the image represented by the image data based on at least the determination result of the first determination section.

5. The extraction unit decomposes a luminance value of the image data acquired by the acquisition unit into frequency components and extracts them as the feature amount, The image projection device described in claim 4, wherein the first judgment unit judges, from the frequency components extracted by the extraction unit, whether the image represented by the image data is at least a first image in which the frequency components exist continuously in a predetermined frequency range, or a second image in which the frequency components exist discretely.

6. a second determination unit that determines whether the image indicated by the image data acquired by the acquisition unit is at least a third image having a predetermined brightness or more, or a fourth image darker than the third image, 4. The image projection device according to claim 1, wherein the classification section classifies the pattern of the image represented by the image data based on at least a result of the determination by the second determination section.

7. An image projection method for projecting an image from a projection optical system, comprising: An acquisition step of acquiring image data; A classification step of classifying an image pattern represented by the acquired image data; a detection step of detecting whether the classified pattern has been switched; a switching step of switching a gamma curve to be applied to the image data to a gamma curve corresponding to the pattern when it is detected that the pattern has been switched; The image projection method includes:

8. A computer that is an image projection device that projects an image from a projection optical system, An acquisition step of acquiring image data; A classification step of classifying an image pattern represented by the acquired image data; a detection step of detecting whether the classified pattern has been switched; a switching step of switching a gamma curve to be applied to the image data to a gamma curve corresponding to the pattern when it is detected that the pattern has been switched; A program for executing the above.

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