JP6350356B2 - Image processing apparatus, projector, image processing method, and program - Google Patents

Description

  The present invention relates to an image processing device, a projector, an image processing method, and a program.

  Patent Document 1 discloses an image processing method in a projector. According to Patent Document 1, the luminance at the center of the image is higher than the luminance at the peripheral due to the influence of the projection lens and light source of the projector. Therefore, in the image processing method of Patent Document 1, the luminance of the central portion of the image is lowered by correcting the image signal so that the luminance of the central portion of the image becomes equal to the luminance of the peripheral portion. Specifically, the luminance is corrected using a correction table in which xy coordinates and correction amounts are associated.

JP 2004-226608 A

  By the way, in recent years, there has been an increasing demand for displaying a brighter image like an HDR (High Dynamic Range) image with a projector. HDR faithfully displays the color, brightness, contrast, dynamic range, etc. of the original video, has a wider color space and brightness than before, and has expanded the number of bits for color information. It is an image that is difficult to display on a conventional display. Therefore, in order to display a brighter image, a high gain screen having a high screen gain is often used. The high screen gain is a screen whose light transmission directivity is sharpened by adjusting a diffusing agent or the like. The screen gain is a luminance angle distribution measured with an angle of light transmitted through the screen with respect to the screen as a viewing angle, and expressed as a ratio of luminance values of the brightest angle and the darkest angle. In the case of a high gain screen, the brightness value in a front view (viewing angle 0 degree) is extremely high with respect to the screen, and the brightness decreases as the absolute value of the viewing angle increases. As a result, the luminance distribution on the screen of the light transmitted through the screen is higher in the central portion than in the peripheral portion. Therefore, even when viewing from the front of the screen, the luminance becomes non-uniform depending on the position in the image. That is, even when an image is displayed with uniform illuminance, if the user is viewing from the center of the screen, the central portion of the image becomes bright and the peripheral portion becomes dark.

  In Patent Document 1, since the luminance distribution on the screen is not taken into consideration, there is a problem that the luminance cannot be corrected appropriately for a projector using a high gain screen. Further, in Patent Document 1, the image signal is corrected so that the brightness of the bright central portion is lowered. Therefore, the overall brightness, particularly the brightness at the center, is reduced, and the merit of using the high gain screen is lost.

  SUMMARY An advantage of some aspects of the invention is that it provides an image processing apparatus, a projector, an image processing method, and a program capable of appropriately correcting an image signal.

  An image processing apparatus according to an aspect of the present invention is an image processing apparatus that processes an image signal used in a projector that projects an image on a screen, and corrects a luminance distribution on the screen according to an address of the image input signal. A correction unit that obtains a correction value to perform, a filter unit that performs a filter process on the image input signal, and a coefficient calculation unit that calculates a coefficient for changing the correction value based on the signal subjected to the filter process And a signal generator that corrects an image input signal using the coefficient and the correction value to generate an image output signal.

  An image processing method according to an aspect of the present invention is an image processing method for processing an image input signal used in a projector that projects an image on a screen, and a luminance distribution on the screen is determined according to an address of the image input signal. Obtaining a correction value to be corrected; filtering the image input signal; calculating a coefficient based on the filtered signal; and inputting the image using the correction value and the coefficient. And correcting the signal to generate an image output signal.

  A program according to an aspect of the present invention is a program that causes a computer to execute an image processing method for processing an image input signal used in a projector that projects an image on a screen, and the image processing method includes: A correction value for correcting the luminance distribution on the screen according to the address of the image, a step of performing a filtering process on the image input signal, and a step of calculating a coefficient based on the signal subjected to the filtering process And correcting the image input signal using the correction value and the coefficient to generate an image output signal.

  According to the present invention, it is possible to provide an image processing apparatus, a projector, an image processing method, and a program that can appropriately correct an image signal.

1 is a diagram illustrating an overall configuration of a display system using a projector according to a first embodiment. It is a figure which shows the luminance distribution on a screen at the time of displaying by uniform illumination intensity. 1 is a block diagram illustrating a configuration of an image processing apparatus according to a first embodiment; It is a figure which shows the profile of the correction value stored in the lookup table. It is a figure which shows the graph for calculating | requiring a coefficient. It is a figure which shows a mode that the luminance value of a peripheral part is correct | amended. FIG. 3 is a block diagram illustrating a configuration of an image processing apparatus according to a second embodiment. It is a figure which shows the graph for calculating | requiring a coefficient in case APL is 90%. It is a figure which shows the graph for calculating | requiring a coefficient in case APL is 10%. It is a figure which shows the whole structure of the display system using the projector concerning Embodiment 3. FIG. FIG. 6 is a block diagram illustrating a configuration of an image processing apparatus according to a third embodiment. It is a figure for demonstrating the reverse gamma correction of the gradation value input-output to an image processing apparatus, and a gamma correction.

Embodiment 1 FIG.
The display system according to the present embodiment is, for example, a display system that displays an HDR image. FIG. 1 shows the overall configuration of the display system. The display system 100 includes a projector 10, an interface unit 30, and a processing device 40.

  The projector 10 is an HDR compatible display (display device), and displays a moving image or a still image. For example, the projector 10 displays an image based on a 16-bit RGB image signal.

  The projector 10 is a rear projection type projector (rear projector), and includes a projection unit 11, a projection lens 12, a mirror 13, and a screen 14. In the present embodiment, the HDR-compatible display is described as the rear projection projector 10, but a front projection projector may be used. That is, the image processing method according to the present embodiment can be applied to image processing in the projector 10 that projects an image on a screen. In order to perform image processing, the projector 10 includes an image processing apparatus described later.

  The projection unit 11 generates projection light based on the image signal in order to project an image on the screen 14. For example, the projection unit 11 includes a light source and a spatial modulator. The light source is a lamp or an LED (Light Emitting Diode). The spatial modulator is an LCOS (Liquid Crystal On Silicon) panel, a transmissive liquid crystal panel, a DMD (Digital Mirror Device), or the like. The projection unit 11 modulates light from the light source with a spatial modulator. The light modulated by the spatial modulator is emitted from the projection lens 12 as projection light. The projection light from the projection lens 12 is reflected by the mirror 13 toward the screen 14. The projection lens 12 has a plurality of lenses, and enlarges and projects the image from the projection unit 11 on the screen 14.

  The projector 10 has a predetermined number of pixels vertically and horizontally, and performs matrix display. Specifically, in the image projected on the screen 14, the projection unit 11 modulates light based on the image signal so that a region corresponding to each pixel has a desired luminance. A gradation value is set for the luminance of the region corresponding to each pixel in accordance with the image signal. That is, the image signal includes a gradation value associated with the pixel address. The projection unit 11 modulates the light based on the image signal so that the luminance is high in a region corresponding to a pixel having a high gradation value. In this way, since light corresponding to the gradation value corresponding to each pixel can be projected onto the screen 14, an image with a desired luminance can be displayed. Here, description will be made assuming that the gradation value corresponding to each pixel in the image input signal is 8 bits (0 to 255).

  The processing device 40 is, for example, a personal computer (PC) or the like, and includes a CPU (Central Processing Unit), a memory, a graphic card, a keyboard, a mouse, an input / output port (input / output I / F), and the like. Input / output ports related to video input / output are, for example, HDMI (High Definition Multimedia Interface), Display Port, DVI (Digital Visual Interface), SDI (Serial Digital Interface), and the like. The processing device 40 stores video files in a memory, a hard disk, or the like. Alternatively, the processing device 40 may be a digital camera. When the processing device 40 is a digital camera, the processing device 40 performs a predetermined process on the video acquired by the image sensor.

  The interface unit 30 has an interface between the processing device 40 and the projector 10. That is, data is transmitted between the processing device 40 and the projector 10 via the interface unit 30. Specifically, the interface unit 30 includes an output port of the processing device 40, an input port of the projector 10, and an AV (Audio Visual) cable that connects the output port and the input port.

  The processing device 40 generates an image input signal transmitted to the interface unit 30. Specifically, the processing device 40 stores a video file in a memory or the like. The processing device 40 generates an image input signal that conforms to the interface standard of the interface unit 30 based on the video file. Then, the processing device 40 outputs an image input signal to the projector 10 via the interface unit 30. That is, the interface unit 30 transmits the image input signal generated by the processing device 40 to the projector 10. The projector 10 generates an image output signal based on the input image input signal. Then, the projector 10 displays a video based on the image output signal.

  The screen 14 is, for example, a high gain screen having a predetermined high screen gain value. In the high gain screen, the luminance varies depending on the angle with respect to the screen (hereinafter referred to as viewing angle) because the directivity of the diffusing agent becomes strong. A high gain screen usually has the highest luminance in front view (in the direction facing the surface of the screen 14 and the viewing angle is 0 degree), and has a luminance distribution in which the luminance decreases as the absolute value of the viewing angle increases. Yes. Therefore, even if an image with uniform illuminance is projected onto the screen 14, the brightness of the screen 14 changes according to the viewing angle.

  The luminance distribution in the front view will be described with reference to FIG. FIG. 2 is a diagram illustrating a luminance distribution on the screen 14 in a front view when an image with uniform illuminance is projected. In FIG. 2, the dotted line is an isoluminance line. FIG. 2 shows luminance profiles in the X direction and the Y direction, respectively. As shown in FIG. 2, in the screen 14, the luminance is high at the central portion, and the luminance is lower toward the end. That is, even when an image is displayed with uniform illuminance, if the user is viewing from the center of the screen, the central portion of the image becomes bright and the peripheral portion becomes dark.

  Therefore, in this embodiment, uniformity correction is performed using the luminance distribution of the screen 14. Specifically, the non-uniformity of the luminance distribution caused by the luminance distribution on the screen 14 is corrected using the image processing apparatus shown in FIG. FIG. 3 is a block diagram illustrating a configuration of the image processing apparatus 20 that processes an image signal used in the projector 10. In the present embodiment, the image processing apparatus 20 is described as being provided in the projector 10, but the image processing apparatus 20 may be provided in the processing apparatus 40. Furthermore, the image processing device 20 may not be a physically single device. For example, part of the image processing may be performed by the processing device 40 and the rest may be performed by the image processing device 20.

  The image processing apparatus 20 includes a filter unit 21, a coefficient calculation unit 22, a lookup table (LUT) 23, a correction unit 24, a detection sensitivity input unit 27, and a signal generation unit 29. The signal generation unit 29 includes a calculation unit 25 and a multiplier 26. An image input signal is input to the image processing apparatus 20. The image input signal includes RGB gradation data and a synchronization signal sync. The gradation data includes gradation values of pixel addresses of R (red), G (green), and B (blue). The image input signal is subjected to signal processing by the image processing device 20 and output as an image output signal.

  The lookup table 23 stores correction values corresponding to the luminance distribution of the screen 14. Here, the correction value is calculated for each pixel address. That is, in the lookup table 23, a correction value is set for each pixel address. In accordance with this correction value, the luminance distribution of the screen 14 is subjected to uniformity correction. Here, the correction value may be stored as the luminance distribution at the viewing position from the luminance distribution of the screen 14 by acquiring the distance from the viewing position from the screen 14 and the size of the screen 14 in advance.

For example, when the user visually recognizes the front view, the luminance distribution in the white display is as shown in FIG. The reciprocal of the luminance in the luminance distribution shown in FIG. 2 is set as the correction value. FIG. 4 shows a profile of correction values stored in the lookup table 23. In FIG. 4, the horizontal axis represents the horizontal position of the screen 14, and the vertical axis represents the correction value. As shown in FIG. 4, the correction value at the center is 1, and the correction value increases toward the end.
As described above, the lookup table 23 stores a correction value corresponding to the luminance distribution of the screen 14. Note that the luminance distribution of the screen 14 may be obtained by actual measurement, or may be calculated from the specification value of the screen gain of the screen 14. When the screen 14 is changed, the lookup table 23 including the correction value is also changed.

  As illustrated in FIG. 3, the synchronization signal sync is input to the correction unit 24. The synchronization signal sync includes a vertical synchronization signal and a horizontal synchronization signal. Therefore, by using the synchronization signal sync, the pixel address of the currently input image input signal is obtained.

  The correction unit 24 acquires a correction value from the lookup table 23. That is, the correction unit 24 reads a correction value corresponding to the pixel address from the lookup table 23. The correction value is used for uniformity correction based on the luminance distribution. The correction unit 24 outputs the correction value B to the calculation unit 25.

  The filter unit 21 performs a filtering process on the image input signal. Specifically, the gradation data of the image input signal and the synchronization signal sync are input to the filter unit 21. The filter unit 21 is set with an LPF (low-pass filter). The filter unit 21 performs a filtering process on the gradation value of the gradation data of the image input signal using, for example, a two-dimensional LPF. By applying the LPF to the gradation value, the image can be blurred. The filter unit 21 may use, for example, an average value filter that calculates an average value of surrounding pixels. The filter unit 21 obtains an average value of 16 × 16 pixels. The filter unit 21 outputs the gradation value of the filtered signal to the coefficient calculation unit 22 as a filter value.

  Further, the detection sensitivity input unit 27 inputs parameters in the filter process to the filter unit 21. For example, when the filter unit 21 applies the LPF to the gradation value of the image input signal, the filtering size in the LPF is input to the filter unit 21. When the filtering size is large, the blurring degree of the image becomes strong. Accordingly, since the brightness is lowered as a whole, the filtered image is closer to the lower brightness side as a whole. On the other hand, when the filtering size is small, the degree of blurring of the image becomes weak. Therefore, since the luminance does not decrease so much as a whole, the degree of the filtered image that approaches the low luminance side becomes small.

  Thus, the filtering size is input from the detection sensitivity input unit 27 to the filter unit 21 as a parameter of detection sensitivity. Note that the user may manually input parameters, or the parameters may be set by default settings at the time of shipment. Further, the parameters may be changed by scene discrimination. Existing processing can be used for scene discrimination. For example, the parameters of filter processing may be changed depending on dark, bright, backlight, person, landscape, and the like.

  The coefficient calculation unit 22 calculates the coefficient C based on the processing result in the filter unit 21. The coefficient calculation unit 22 outputs the calculated coefficient C to the calculation unit 25. FIG. 5 shows the processing in the coefficient calculation unit 22. FIG. 5 is a graph showing the relationship between the input value IN (filter value) input from the filter unit 21 to the coefficient calculation unit 22 and the output value OUT (coefficient C) output from the coefficient calculation unit 22.

  The filter value input from the filter unit 21 to the coefficient calculation unit 22 is shown on the horizontal axis as an input value IN (0 to 255), and the coefficient C output from the coefficient calculation unit 22 to the calculation unit 25 is shown as an output value OUT on the vertical axis. It shows. When the input value IN is 0 to 128, the coefficient is 1.0. When the input value IN is 129 to 255, the coefficient decreases linearly with respect to the input value IN in the present embodiment. Here, the coefficient change may be nonlinear. When the input value IN is 255, the coefficient is 0.0. Thus, the coefficient C changes in the range of 0 to 1 according to the input gradation value.

  In this way, the output value OUT is constant until the input value IN exceeds the displacement point P. When the displacement point P, which is a threshold value, is exceeded, the output value OUT decreases linearly in the present embodiment as the input value IN increases. Here, the change in the output value OUT may be non-linear. Thus, the coefficient calculation unit 22 compares the filter value obtained by the filter unit 21 with the threshold value (displacement point P), and determines whether or not the filter value is larger than the threshold value. The coefficient calculation unit 22 sets a coefficient that is constant in an area where the filter value is equal to or smaller than the threshold value, and that gradually decreases as the gradation value of the filter image increases in an area where the filter value is larger than the threshold value.

  Therefore, the coefficient is constant up to the threshold value, and when the threshold value is exceeded, the coefficient C decreases according to the filter value. In the example of FIG. 5, the displacement point P (threshold value) is 128, but the displacement point P is not limited to 128. In this way, the coefficient calculation unit 22 calculates the coefficient C based on the filtered signal. A coefficient C is calculated for each pixel address.

  Then, the coefficient calculation unit 22 outputs a coefficient C for increasing the gradation value to the calculation unit 25. Further, the correction value B from the correction unit 24 is also input to the calculation unit 25. The calculation unit 25 calculates the calculation value A based on the correction value B and the coefficient C. Specifically, the calculation unit 25 calculates a calculation value A based on the following equation (1). Here, since the coefficient C is in the range of 0 to 1, it is a coefficient that reduces the correction value B as a whole.

A = (B−1.0) × C + 1.0 (1)

  The calculation unit 25 calculates a calculation value A for each pixel address. The calculation unit 25 outputs the calculation value A to the multiplier 26. The multiplier 26 receives gradation data of the image input signal. The multiplier 26 multiplies the gradation value of the gradation data at the corresponding address by the operation value A to generate an image output signal. The multiplier 26 outputs an image output signal having a gradation value obtained by multiplying the gradation value by the arithmetic value A.

  Thus, the calculation unit 25 and the multiplier 26 constitute a signal generation unit 29 that corrects the gradation value using the coefficient C and the correction value B and generates an image output signal. Then, the projection unit 11 spatially modulates light according to the gradation value of the image output signal. That is, an image having a predetermined luminance is projected from the projection unit 11 onto the screen 14 in accordance with the gradation value of the image output signal output from the multiplier 26. That is, the luminance in the area corresponding to each pixel of the screen 14 is in accordance with the gradation value of the image output signal from the multiplier 26. In this way, the image input signal can be corrected appropriately. Therefore, in the area corresponding to each pixel on the screen 14, an image whose uniformity has been corrected with the coefficient and the calculated value based on the correction value is displayed.

  As described above, in the present embodiment, the coefficient C calculated by the coefficient calculation unit 22 based on the filter value is used. That is, the calculation unit 25 and the multiplier 26 calculate the level of the image input signal so that the coefficient C decreases according to the filter value when the input value IN exceeds the threshold by the calculation value A based on the coefficient C and the correction value B. The key value is corrected. Therefore, as shown in FIG. 6, the luminance in the peripheral portion of the screen 14 can be corrected based on the luminance distribution on the screen 14, and when the input value IN exceeds the threshold value, the correction value is further reduced. Thus, the luminance can be prevented from being saturated regardless of the input value IN. That is, the uniformity correction is performed so that the output gradation value (R′G′B ′) in the peripheral portion of the screen 14 is increased. On the other hand, since the correction value B is 1 at the center of the screen 14, the calculated value A of Expression (1) is 1 regardless of the coefficient C. Therefore, it is possible to prevent whiteout at the center of the screen 14.

  In the above formula (1), the calculation value A is 1 or more. The multiplier 26 obtains an output gradation value by multiplying the input gradation value by one or more calculation values A. Therefore, the gradation value increases due to the uniformity correction. Therefore, it is possible to prevent a decrease in luminance due to uniformity correction. Thereby, it is possible to display an image with high luminance. Thus, according to the present embodiment, it is possible to appropriately correct the image signal. Luminance unevenness caused by the screen 14 can be improved. Without reducing the luminance at the central portion of the screen 14, the luminance of the peripheral portion is aligned with the central portion having the highest luminance, and a bright image with a small luminance distribution can be displayed. Furthermore, when the luminance of the video signal exceeds the threshold value, it is possible to suppress overcorrection by reducing the correction value.

  The scene of the image to be displayed can be detected by the filter processing in the filter unit 21. In a bright scene, the coefficient is small because the user's sensitivity to uneven brightness is low. On the other hand, in a dark scene, the coefficient is large because the user's visibility to luminance unevenness is high. As described above, in the present embodiment, a scene is detected by the filter process, and the correction amount of the correction value is controlled according to the detected scene. Therefore, the image input signal can be corrected appropriately. The correction unit 24 may acquire a correction value for correcting the gradation value to the maximum luminance value in the luminance distribution. In this way, display with high luminance becomes possible.

Embodiment 2. FIG.
A projector and an image processing method according to the second embodiment will be described with reference to FIG. FIG. 7 is a block diagram illustrating a configuration of the image processing device 20 used in the projector 10. In the present embodiment, an APL (Average Picture Level) detection unit 28 is provided in the image processing apparatus 20. Note that the configuration other than the APL detection unit 28 is the same as that of the first embodiment, and thus the description thereof is omitted.

  The APL detection unit 28 receives gradation data of the image input signal RGB. The APL detection unit 28 generates an APL signal based on the gradation data. Here, the APL detection unit 28 generates an APL signal based on the average luminance for one frame, for example. For example, the APL detection unit 28 obtains the average value of gradation values in one frame as the average luminance. Then, the ratio of the average luminance to the maximum luminance value (255) is output as an APL signal. The APL signal is in the range of 0 to 100%. When displaying a white frame, the APL signal is 100%, and when displaying a black frame, the APL signal is 0%.

  The APL detection unit 28 outputs the APL signal to the coefficient calculation unit 22. The coefficient calculation unit 22 changes the threshold value (displacement point P) shown in FIG. 5 according to the APL signal. For example, the coefficient calculation unit 22 calculates the displacement point P based on the following equation (2).

  P = 255− (255 × APL) = 255 × (1-APL) (2)

  When the APL signal is 50%, the coefficient calculation unit 22 calculates the coefficient C according to the graph shown in FIG. When the APL signal is 90%, the displacement point P = 26 from equation (2). When the APL signal is 90%, a graph for obtaining the coefficient C is as shown in FIG. When the APL signal is 10%, the displacement point P = 230 from equation (2). When the APL signal is 10%, a graph for obtaining the coefficient C is as shown in FIG.

  The expression (2) can be changed to a mathematical expression having nonlinearity including a state that is 255 when APL is 0 and 0 when APL is 1 (100%).

  As described above, the displacement point P (threshold value) is changed according to the average luminance in the image input signal. In this way, the coefficient C can be calculated more appropriately. That is, when the average luminance of the gradation data is small, the number of pixel addresses having the maximum coefficient C (1) increases. Therefore, display with higher luminance can be performed. On the other hand, when the average luminance of the gradation data is large, the number of pixel addresses having the maximum coefficient C decreases. Therefore, overexposure can be prevented, and uniformity correction can be performed appropriately.

Embodiment 3 FIG.
A projector 10 according to the present embodiment will be described with reference to FIG. In the present embodiment, a sensor 15 that detects the position of the user is provided on the front surface of the projector 10. The sensor 15 detects the position of the user who visually recognizes the image projected on the screen 14. For example, the sensor 15 has a camera or the like, and detects the user's face position by performing face recognition processing. Thereby, the viewing angle with respect to the screen 14 can be detected. The projector 10 changes the correction value based on the positional relationship between the user position detected by the sensor 15 and the screen 14. The sensor 15 may be attached to the user. In addition, about the content which overlaps with Embodiment 1, description is abbreviate | omitted suitably.

  Image processing according to the present embodiment will be described with reference to FIG. FIG. 11 is a block diagram showing an image processing device 20 used in the projector 10. In FIG. 11, a sensor 15 and an LUT acquisition unit 51 are added to the configuration shown in FIG. Since the configuration other than the sensor 15 and the LUT acquisition unit 51 is the same as that of the first embodiment, the description thereof is omitted.

  The sensor 15 detects the position of the user with respect to the screen 14 as described above. The sensor 15 outputs the user position information to the LUT acquisition unit 51 from the positional relationship between the detected user position and the screen 14. The LUT acquisition unit 51 acquires the correction value from the LUT according to the user position information. For example, the viewing angle changes according to the position of the user with respect to the screen 14. Therefore, the LUT acquisition unit 51 acquires a correction value corresponding to the viewing angle. The LUT acquisition unit 51 may select an optimal LUT according to the viewing angle from a plurality of LUTs stored in advance. The lookup table 23 stores the LUT acquired by the LUT acquisition unit 51.

  Thus, in the present embodiment, the correction value is changed according to the position of the user with respect to the screen 14. By doing so, it is possible to display an image uniformly on the screen surface with high brightness, regardless of the direction the user views from. That is, appropriate correction can be performed even when the user moves. Furthermore, since the gradation value of the image input signal is corrected using the correction value multiplied by the coefficient, the same effect as in the first embodiment can be obtained. Of course, the configuration and method of the third embodiment may be applied to the image processing apparatus 20 according to the second embodiment. For example, you may add the APL detection part 28 of FIG. 7 to the structure shown in FIG.

  In the first to third embodiments, the presence / absence of uniformity correction may be switched. For example, when many users visually recognize the image on the screen 14, the viewing angle varies depending on the user. Therefore, when the above uniformity correction is performed, an image may not be displayed with appropriate brightness for some users. Therefore, when the number of users is one or a small number, the uniformity correction shown in the first and second embodiments may be performed, and when a large number of users visually recognize, the uniformity correction may not be performed. Further, the number of users and the position for each user may be detected by the sensor 15, and the presence / absence of uniformity correction may be switched based on the detection result.

  Note that the processing in the image processing apparatus 20 is linear processing. Therefore, as shown in FIG. 13, inverse gamma correction and gamma correction are performed as pre-processing and post-processing of the image signal. The gradation value of the image input signal input to the image processing apparatus 20 is subjected to inverse gamma correction. That is, inverse gamma correction is performed in advance so that the gradation value processed by the image processing apparatus 20 is linear with the luminance. Then, the image processing apparatus 20 processes gradation values having a linear relationship with luminance. Further, the gradation value of the image output signal output from the image processing device 20 is output to the projector 10 after being gamma corrected. In inverse gamma correction and gamma correction, a one-dimensional lookup table is used.

  Part or all of the above processing may be executed by a computer program. The programs described above can be stored and provided to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)). The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

DESCRIPTION OF SYMBOLS 10 Projector 11 Projection part 12 Projection lens 13 Mirror 14 Screen 15 Sensor 20 Image processing apparatus 21 Filter part 22 Coefficient calculation part 23 Look-up table 24 Correction part 25 Calculation part 26 Multiplier 27 Detection sensitivity input part 28 APL detection part 29 Signal generation Unit 30 interface unit 40 processing unit 51 LUT acquisition unit

Claims (9)

An image processing apparatus that processes an image input signal used in a projector that projects an image on a screen,
A correction unit that acquires a correction value for each pixel address corresponding to the screen in order to correct the luminance distribution on the screen according to the address of the image input signal;
A filter unit that performs a filtering process on the image input signal;
A detection sensitivity input unit for inputting a filtering size in the filter processing;
A coefficient calculation unit that calculates a coefficient for changing the correction value based on the signal subjected to the filtering process;
An image processing apparatus comprising: a signal generation unit that generates an image output signal by correcting an image input signal using the coefficient and the correction value.   The image processing apparatus according to claim 1, wherein the correction unit acquires a correction value to be corrected to a maximum luminance value in the luminance distribution.   The image processing apparatus according to claim 1, wherein the filter unit applies a low-pass filter to the image input signal and performs a filtering process on a gradation value of the image input signal. . A sensor for detecting the position of the user,
The image processing apparatus according to claim 1, wherein the correction value is changed according to a user position and a screen position detected by the sensor. The coefficient calculation unit compares a threshold value set in advance with a gradation value of the signal subjected to the filtering process,
In a region where the gradation value of the signal subjected to the filtering process is equal to or less than the threshold value, the coefficient is constant,
In a region where the gradation value of the signal subjected to the filtering process is larger than the threshold value, the coefficient is calculated so that the coefficient gradually decreases as the gradation value of the signal subjected to the filtering process increases. The image processing apparatus of any one of Claims 1-4.   The image processing apparatus according to claim 5, wherein the coefficient calculation unit changes the threshold value according to an average luminance corresponding to an image input signal. The image processing apparatus according to any one of claims 1 to 6,
A projector comprising: a projection unit that projects light onto the screen in accordance with an image output signal generated by the image processing device. An image processing method for processing an image input signal used in a projector that projects an image on a screen,
Obtaining a correction value for each pixel address corresponding to the screen in order to correct the luminance distribution on the screen according to the address of the image input signal;
Filtering the image input signal;
Inputting a filtering size in the filtering process;
Calculating a coefficient based on the filtered signal;
And correcting the image input signal using the correction value and the coefficient to generate an image output signal. A program for causing a computer to execute an image processing method for processing an image input signal used in a projector that projects an image on a screen,
The image processing method includes:
Obtaining a correction value for each pixel address corresponding to the screen in order to correct the luminance distribution on the screen according to the address of the image input signal;
Filtering the image input signal;
Inputting a filtering size in the filtering process;
Calculating a coefficient based on the filtered signal;
And correcting the image input signal using the correction value and the coefficient to generate an image output signal.

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