Optical device

Abstract

An optical device (10) is provided, the optical device (10) comprising: a lens system (12); an image sensor (13) for receiving light passing through the lens system (12), wherein the image sensor (13) is a binning type image sensor with a variable pixel pitch; and an intensity controller (11) for reducing the intensity of light passing through at least one reduced area thereof to change the intensity distribution of light entering the lens system (12) according to the pixel pitch of the image sensor (13).

Description

Technical Field

[0001] The present invention relates to a method for reducing the moire effect, an optical device capable of implementing the method, and a device having the optical device. For example, the device may be a mobile phone, a smart phone, a tablet computer, a personal computer, a digital still camera, a digital video camera, a surveillance camera, etc. Background Art

[0002] Recent developments in manufacturing technology have increased the number of pixels in image sensors installed in devices such as mobile phones, smartphones, tablets, personal computers, digital still cameras, digital video cameras or surveillance cameras.

[0003] In some cases, an increase in the number of pixels leads to a decrease in the pixel pitch of an image sensor because the size of an image sensor that can be installed in a device is limited. A decrease in the pixel pitch of an image sensor may reduce light receiving sensitivity. In this regard, a binning type sensor with a variable pixel pitch has recently attracted attention because it can improve light receiving sensitivity.

[0004] The binning type sensor is characterized in that the pixel signals from adjacent pixels are combined into one result signal to virtually combine multiple adjacent pixels into one pixel. For example, there are currently horizontal binning type sensors, vertical binning type sensors, and full binning type sensors. Horizontal binning type and vertical binning type sensors can virtually combine a pair of adjacent pixels arranged in the row direction and column direction, respectively, and double their pixel pitch. In addition, the full binning type sensor can virtually combine adjacent N×N pixels arranged in two dimensions and increase the pixel pitch by N times, where N is set to be equal to or greater than 2. For example, a binning operation that increases the pixel pitch by 2 times can be called "2×2 binning".

[0005] However, the increase in pixel pitch may cause the appearance of moiré effect in the generated image, because the moiré effect becomes noticeable when the spatial frequency of the captured object is greater than the Nyquist frequency corresponding to the pixel pitch of the image sensor. Although some conventional cameras are equipped with an optical low pass filter (OLPF) to mitigate the moiré effect, since the cutoff frequency of the conventional OLPF is fixed, the moiré effect is not effectively mitigated when the pixel pitch of the image sensor changes. Summary of the invention

[0006] The embodiment provides an optical device, a method for reducing the moire effect, and a device having the optical device. The device may be a mobile phone, a smart phone, a tablet computer, a personal computer, a digital still camera, a digital video camera, a surveillance camera, etc.

[0007] A first aspect of the present embodiment provides an optical device. In a first possible implementation form of the first aspect, the optical device includes: a lens system; an image sensor for receiving light passing through the lens system, wherein the image sensor is a binning type image sensor with a variable pixel pitch; and an intensity controller for reducing the intensity of light passing through at least one reduced area thereof to change the intensity distribution of light entering the lens system according to the pixel pitch of the image sensor.

[0008] According to a first possible implementation form of the first aspect, the intensity distribution of light entering the lens system can be changed according to the pixel pitch of the image sensor, thereby substantially reducing the modulation transfer function (MTF) curve of the optical device at a target spatial frequency related to the pixel pitch of the image sensor.

[0009] For example, the target spatial frequency may be a Nyquist frequency corresponding to a pixel pitch of an image sensor. Substantially lowering the MTF curve at the corresponding target spatial frequency may mitigate a moire effect that occurs on an image generated from an output signal from the image sensor.

[0010] In a first possible implementation form of the first aspect, even if the pixel pitch of the image sensor is changed, the moire effect can be effectively mitigated by forming an intensity distribution that provides a suitable MTF curve related to the current pixel pitch of the image sensor.

[0011] A second possible implementation form of the first aspect provides: an optical device according to the first possible implementation form of the first aspect, wherein the at least one reduction region is used to substantially reduce the MTF curve of the optical device near the Nyquist frequency corresponding to the pixel pitch of the image sensor.

[0012] When capturing an object with a spatial frequency greater than the Nyquist frequency corresponding to the pixel pitch of the image sensor, the moire effect becomes noticeable. In a second possible implementation form of the first aspect, by applying an appropriate intensity distribution, the MTF curve of the optical device can be controlled to be sufficiently reduced near the Nyquist frequency corresponding to the pixel pitch of the image sensor, so that the moire effect can be effectively mitigated even if the pixel pitch of the image sensor changes.

[0013] Alternatively, the intensity controller may be an intensity control mask for reducing the intensity of light passing through at least one reduced region thereof.The intensity control mask may be a film, panel, sheet, etc. having intensity controller features.

[0014] In some exemplary embodiments, the intensity control mask may be an electrochromic device, a liquid crystal device, etc. These are exemplary elements that may be used as an intensity control mask, and it should be noted that this exemplary listing is not intended to be limiting.

[0015] Electrochromic devices can be made using Ta 2 O 5 and ZrO 2 Solid-state electrochromic devices using solid inorganic or organic materials as electrolytes, or laminated electrochromic devices using liquid gels as electrolytes. Electrochromic devices can be used to control optical properties such as refraction, absorption, and reflectivity by applying voltage.

[0016] If the electrochromic device is used as an intensity control mask, the electrochromic device controls the absorption of its target area to reduce the intensity of light passing through the target area. In this article, such a target area is referred to as a reduction area. The absorption of light by at least one reduction area can form an appropriate light intensity distribution to reduce the MTF curve, thereby reducing the moire effect in the generated image.

[0017] Similarly, even in another case of using a liquid crystal device as an intensity control mask, the intensity distribution changes, and the moire effect can be mitigated by lowering the MTF curve near the target frequency. The present invention is not limited to these exemplary cases, and other modified examples are also applicable.

[0018] A third possible implementation form of the first aspect provides: an optical device according to the second possible implementation form of the first aspect, wherein the intensity control mask is divided into a plurality of annular areas with the optical axis of the lens system as the center, and each annular area and the area within the innermost annular area can be a reduction area with low transmittance or a non-reduction area with high transmittance.

[0019] In a third possible implementation form of the first aspect, each reduction region has an axisymmetric shape centered on the optical axis of the lens system, and various circular stripe patterns can be achieved by controlling a voltage applied to at least a portion of the annular region and / or a region within the innermost annular region. The target frequency at which the MTF curve of the optical device is sufficiently reduced can be finely controlled by switching between circular stripe patterns on the intensity control mask according to the pixel pitch of the image sensor.

[0020] A second aspect of the present embodiment provides a method for reducing the moiré effect. In a first possible implementation form of the second aspect, the method includes: reducing the intensity of light passing through at least one reduced area of ​​the intensity controller by an intensity controller to change the intensity distribution of light entering the lens system according to the pixel pitch of an image sensor as a binning type image sensor with a variable pixel pitch; and receiving, by the image sensor, the light passing through the lens system.

[0021] According to a first possible implementation form of the second aspect, the intensity distribution of light entering the lens system can be changed according to the pixel pitch of the image sensor, thereby substantially reducing the MTF curve of the optical device at a target spatial frequency related to the pixel pitch of the image sensor.

[0022] For example, the target spatial frequency may be a Nyquist frequency corresponding to a pixel pitch of an image sensor. Substantially lowering the MTF curve at the corresponding target spatial frequency may mitigate a moire effect that occurs on an image generated from an output signal from the image sensor.

[0023] In a first possible implementation form of the second aspect, even if the pixel pitch of the image sensor is changed, the moire effect can be effectively mitigated by forming an intensity distribution that provides a suitable MTF curve related to the current pixel pitch of the image sensor.

[0024] A second possible implementation form of the second aspect provides: according to the method of the first possible implementation form of the second aspect, determining the at least one reduction area so that the MTF curve of the optical device including the intensity controller and the lens system decreases near the Nyquist frequency corresponding to the pixel pitch of the image sensor.

[0025] As described above, when capturing an object having a spatial frequency greater than the Nyquist frequency corresponding to the pixel pitch of the image sensor, the moire effect becomes apparent. In a second possible implementation form of the second aspect, by applying an appropriate intensity distribution, the MTF curve of the optical device can be controlled to be sufficiently reduced near the Nyquist frequency corresponding to the pixel pitch of the image sensor, so that the moire effect can be effectively mitigated even if the pixel pitch of the image sensor changes.

[0026] Alternatively, the intensity controller may be an intensity control mask for reducing the intensity of light passing through at least one reduced region thereof.The intensity control mask may be a film, panel, sheet, etc. having intensity controller features.

[0027] In some exemplary embodiments, the intensity control mask may be an electrochromic device, a liquid crystal device, etc. These are exemplary elements that may be used as an intensity control mask, and it should be noted that this exemplary listing is not intended to be limiting.

[0028] Electrochromic devices can be made using Ta 2 O 5 and ZrO 2 Solid-state electrochromic devices using solid inorganic or organic materials as electrolytes, or laminated electrochromic devices using liquid gels as electrolytes. Electrochromic devices can be used to control optical properties such as refraction, absorption, and reflectivity by applying voltage.

[0029] If the electrochromic device is used as an intensity control mask, the electrochromic device controls the absorption of its target area to reduce the intensity of light passing through the target area. In this article, such a target area is referred to as a reduction area. The absorption of light by at least one reduction area can form an appropriate light intensity distribution to reduce the MTF curve, thereby reducing the moire effect in the generated image.

[0030] Similarly, even in another case of using a liquid crystal device as an intensity control mask, the intensity distribution changes, and the moire effect can be mitigated by lowering the MTF curve near the target frequency. The present invention is not limited to these exemplary cases, and other modified examples are also applicable.

[0031] A third possible implementation form of the second aspect provides: a method according to the second possible implementation form of the second aspect, wherein the intensity control mask is divided into a plurality of annular areas with the optical axis of the lens system as the center, and each annular area and the area within the innermost annular area can be a reduced area with low transmittance or a non-reduced area with high transmittance.

[0032] In a third possible implementation form of the first aspect, each reduction region has an axisymmetric shape centered on the optical axis of the lens system, and various circular stripe patterns can be achieved by controlling a voltage applied to at least a portion of the annular region and / or a region within the innermost annular region. The target frequency at which the MTF curve of the optical device is sufficiently reduced can be finely controlled by switching between circular stripe patterns on the intensity control mask according to the pixel pitch of the image sensor.

[0033] A third aspect of this embodiment provides a device, comprising: an optical device according to any one of the first to third possible implementation forms of the first aspect; and a processor, for generating an image based on an output signal from the image sensor to store the image in a memory.

[0034] The fourth aspect of this embodiment provides a program that enables a computer to execute the method according to any one of the first to third possible implementation forms of the second aspect. The fifth aspect of this embodiment provides a non-transitory computer-readable storage medium that stores a program that enables a computer to execute the method according to any one of the first to third possible implementation forms of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic block diagram for describing the configuration of an apparatus and an optical device in the apparatus provided according to an embodiment of the present invention.

[0036] Figure 2 is a schematic diagram for describing the arrangement of an intensity distribution (ID) controller and a lens group in an optical device provided according to an embodiment of the present invention.

[0037] Figure 3 It is a schematic diagram for describing a controllable area of ​​an ID controller provided according to an embodiment of the present invention.

[0038] Figure 4 A first example of a reduced area of ​​an ID controller provided according to an embodiment of the present invention is shown.

[0039] Figure 5 A second example of a reduced area of ​​an ID controller provided according to an embodiment of the present invention is shown.

[0040] Figure 6 A third example of a reduced area of ​​an ID controller provided according to an embodiment of the present invention is shown.

[0041] Figure 7 A fourth example of a reduced area of ​​an ID controller provided according to an embodiment of the present invention is shown.

[0042] Figure 8 A fifth example of a reduced area of ​​an ID controller provided according to an embodiment of the present invention is shown.

[0043] Fig. 9 A sixth example of a reduced area of ​​an ID controller provided according to an embodiment of the present invention is shown.

[0044] Fig.10 A first example of a modulation transfer function (MTF) curve of an optical device according to an embodiment of the present invention is shown.

[0045] Fig.11A second example of an MTF curve of an optical device provided according to an embodiment of the present invention is shown.

[0046] Fig.12 A flow chart for describing a method implemented by a device according to an embodiment of the present invention is shown.

[0047] Fig.13A A first preferred configuration of the reduced area of ​​the ID controller is shown.

[0048] Fig. 13B The MTF curve corresponding to the first preferred configuration of the reduced region is shown.

[0049] Fig.14A A second preferred configuration of the reduced area of ​​the ID controller is shown.

[0050] Fig. 14B The MTF curve for the second preferred configuration corresponding to the reduced region is shown.

[0051] Fig.15A A third preferred configuration of the reduced area of ​​the ID controller is shown.

[0052] Fig. 15B The MTF curve for the third preferred configuration corresponding to the reduced region is shown. DETAILED DESCRIPTION

[0053] The technical scheme of the embodiment will be described below in conjunction with the accompanying drawings. It should be understood that the embodiments described below do not represent all embodiments, but are only some embodiments related to the present invention. It should be noted that other embodiments that can be derived from the embodiments described below by those skilled in the art without paying creative labor are within the scope of protection of the present invention.

[0054] The following embodiments relate to a method for reducing the moire effect, an optical device capable of implementing the method, and a device having the optical device. The present embodiments can be applied to various devices such as mobile phones, smart phones, tablet computers, personal computers, digital still cameras, digital cameras, surveillance cameras, etc.

[0055] (Exemplary Configuration of Optical Devices and Equipment) Figure 1 Configurations of optical devices and apparatuses provided according to embodiments of the present invention are described.

[0056] Figure 1 is a schematic block diagram for describing the configuration of an apparatus and an optical device in the apparatus provided according to an embodiment of the present invention. Figure 1 The device 10 shown in FIG. 1 is an example of a device provided according to an embodiment of the present invention.

[0057] like Figure 1As shown, the device 10 includes an intensity distribution (ID) controller 11, a lens system 12, an image sensor 13, a processor 14, and a memory 15. Optionally, the device 10 may further include at least one dedicated controller for controlling the operation of the ID controller 11 and / or the image sensor 13.

[0058] The ID controller 11, the lens system 12 and the image sensor 13 may form an optical device provided according to an embodiment of the present invention. For example, the ID controller 11 may operate as an intensity control mask for changing the intensity distribution of light entering the lens system 12. The intensity control mask may be an electrochromic (EC) device, a liquid crystal (LC) device, etc. These are exemplary elements that may be used as an intensity control mask, and it should be noted that, here, such exemplary enumeration is not intended to be limiting.

[0059] The lens system 12 includes at least one lens group, a stop (aperture), and an optical filter including an infrared (IR) cut-off filter. For example, the lens system 12 may have Figure 2 The structure shown. Figure 2 Schematic diagram for describing the arrangement of a WF controller and a lens group in an optical device according to an embodiment of the present invention.

[0060] exist Figure 2 In the example of FIG. 1 , the lens system 12 includes a stop ST and lenses L1 to L7, and the WF controller 11 is located on the object side of the lens system 12. Figure 2 In the figure, the Z direction corresponds to the optical axis AX of the lens system 12, and the surface of the WF controller 11 is perpendicular to the Z direction and corresponds to the XY plane. Figure 2 OP1 and OP2 in FIG. 8 represent optical paths that are symmetrical with respect to the optical axis AX.

[0061] The image sensor 13 may be a charge coupled device (CCD) image sensor, a complementary metal-oxide-semiconductor (CMOS) image sensor, etc. The image sensor 13 is a combined image sensor with a variable pixel pitch. In addition, the image sensor 13 is used to receive light passing through the lens system 12.

[0062] The processor 14 is used to generate an image according to the output signal from the image sensor 13 and store the image in the memory 15. For example, the processor 14 can be a central processing unit (CPU), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), a graphics processing unit (GPU), etc.

[0063] The memory 15 may be a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), a solid state drive (SSD), a portable storage medium, etc. In addition, the memory 15 may store a program to enable the processor 14 to perform operations for controlling at least one of the ID controller 11, the lens system 12, and the image sensor 13. The program may be provided to the device 10 via a data carrying method (e.g., a non-transitory computer-readable storage medium, a local area network, and / or a wide area network, etc.).

[0064] In an embodiment of the present invention, the ID controller 11 is used to reduce the intensity of light passing through at least one reduction area thereof to change the intensity distribution of light entering the lens system 12 according to the pixel pitch of the image sensor 13 .

[0065] In some exemplary embodiments, the ID controller 11 may be an electrochromic (EC) device, a liquid crystal (LC) device, etc. These are exemplary elements that may be used as an intensity control mask, and it should be noted that such exemplary listing is not intended to be limiting.

[0066] EC devices can be made using Ta 2 O 5 and ZrO 2 Solid-state electrochromic devices using solid inorganic or organic materials as electrolytes, or laminated electrochromic devices using liquid gels as electrolytes. EC devices can be used to control optical properties such as refraction, absorption, and reflectivity by applying voltage.

[0067] If the EC device is used as the ID controller 11, the EC device controls the absorption of its target area to reduce the intensity of light passing through the target area. Such a target area is the reduction area mentioned above. The absorption of light by at least one reduction area can form an appropriate light intensity distribution to reduce the MTF curve, thereby reducing the moire effect in the generated image.

[0068] Similarly, even in another case of using an LC device as the ID controller 11, the intensity distribution changes, and the moire effect can be mitigated by lowering the MTF curve near the target frequency. The present invention is not limited to these exemplary cases, and other modified examples are also applicable.

[0069] Typically, the moire effect becomes noticeable when capturing objects with a spatial frequency greater than the Nyquist frequency corresponding to the pixel pitch of the image sensor used for capturing.

[0070] In an embodiment of the present disclosure, the intensity distribution of light entering the lens system 12 can be changed to an appropriate intensity distribution for sufficiently reducing the MTF curve of the optical device near the Nyquist frequency corresponding to the current pixel pitch of the image sensor 13. This may reduce the moire effect that appears on the generated image. In addition, since at least one appropriate reduction area is selected according to the pixel pitch of the image sensor 13, the moire effect can be reduced even in consideration of the change in the pixel pitch through the binning operation.

[0071] (Method for controlling the shape of the deformation area) Figure 3 Describes methods for controlling the shape of the reduction region. Figure 3 It is a schematic diagram for describing a controllable area of ​​an ID controller provided according to an embodiment of the present invention. Figure 3 Only one of the exemplary cases of the present embodiment is shown, and it should be noted that the present invention is not limited to these exemplary cases, and other modified examples are also applicable.

[0072] like Figure 3 As shown, the ID controller 11 can be divided into annular areas A2 to A5 centered on the optical axis AX of the lens system 12, and an area A1 within the innermost annular area A2. Optionally, the number of divided areas in the ID controller 11 can be equal to or greater than 6, or equal to or less than 4.

[0073] Each of the areas A1 to A5 may be a reduction area or a non-reduction area (e.g., a transparent area). For example, an area of ​​the ID controller 11 to which a predetermined voltage is applied is used as a reduction area, and another area of ​​the ID controller 11 to which a voltage is not applied is used as a non-reduction area. The intensity of light passing through the reduction area is reduced, while the intensity of light passing through the non-reduction area remains unchanged.

[0074] exist Figure 3 In the example of FIG. 1 , each divided area has an axisymmetric shape centered on the optical axis of the lens system 12. In this case, various circular stripe patterns can be realized by controlling the voltage applied to at least a portion of the annular area and / or an area within the innermost annular area, such as Figures 4 to 9 shown. Figures 4 to 9 An exemplary pattern formed by at least one reduced area of ​​an ID controller provided according to an embodiment of the present invention is shown.

[0075] Figure 4 The example indicates that areas A2-A5 are set as reduced areas, and the remaining area A1 is set as a non-reduced area. In this example, the intensity of light passing through areas A2-A5 is reduced. Here, the configuration of areas A1 to A5 is represented by using vectors such as (y1, y2, y3, y4, y5), where y1 to y5 represent the states of areas A1 to A5, respectively, and each of y1, y2, y3, y4 and y5 is 0 if it is a reduced area, and 1 if it is a non-reduced area.

[0076] Figure 4 The example of indicates that areas A2-A5 are set as reduced areas, and the remaining area A1 is set as a non-reduced area. In this example, the states of areas A1 to A5 are represented by (0, 1, 1, 1, 1), and light passing through areas A2-A5 is absorbed at a specific rate related to the predetermined transmittance of the reduced area.

[0077] Optionally, the transmittance (or absorption coefficient) of each reduced area may be determined so as to sufficiently reduce the MTF curve at a target spatial frequency associated with the binning type (e.g., 2x2 binning, 4x4 binning, etc.). In this regard, since the frequency at which the MTF curve is sufficiently low depends on the shape of the reduced area, it is preferred to determine the transmittance in consideration of the shape of the reduced area so that the MTF curve is sufficiently low at the target frequency. To simplify the description, the following description is made with an example in which the transmittance is set to a given value.

[0078] Figure 5 The example of indicates that regions A1, A3-A5 are set as reduced regions, and the remaining region A2 is set as a non-reduced region. In this example, the states of regions A1 to A5 are represented by (1, 0, 1, 1, 1), and light passing through regions A1, A3-A5 is absorbed at a specific rate.

[0079] Figure 6 The example of indicates that areas A1-A2 and A4-A5 are set as reduction areas, and the remaining area A3 is set as a non-reduction area. In this example, the states of areas A1 to A5 are represented by (1, 1, 0, 1, 1), and light passing through areas A1-A2 and A4-A5 is absorbed at a specific rate.

[0080] Figure 7 The example of indicates that areas A1 and A4-A5 are set as reduced areas, and the remaining areas A2-A3 are set as non-reduced areas. In this example, the states of areas A1 to A5 are represented by (1, 0, 0, 1, 1), and light passing through areas A1 and A4-A5 is absorbed at a specific rate.

[0081] Figure 8 The example of indicates that regions A2 and A4 are set as reduced regions, and the remaining regions A1, A3, and A5 are set as non-reduced regions. In this example, the states of regions A1 to A5 are represented by (0, 1, 0, 1, 0), and light passing through regions A2 and A4 is absorbed at a specific rate.

[0082] Fig. 9 The example of indicates that regions A1, A3, and A5 are set as reduction regions, and the remaining regions A2 and A4 are set as non-reduction regions. In this example, the states of regions A1 to A5 are represented by (1, 0, 1, 0, 1), and light passing through regions A1, A3, and A5 is absorbed at a specific rate.

[0083] As described above, by changing the combination of the areas set in the reduction area or the non-reduction area between the areas A1 to A5, various patterns formed by the reduction area and the non-reduction area of ​​the ID controller 11 are realized. The MTF curve of the optical device can be changed according to the pattern formed by the reduction area and the non-reduction area. Therefore, the device 10 can finely control the MTF characteristics of the optical device.

[0084] For example, the processor 14 may control the ID controller 11 to form a pattern corresponding to (1, 1, 0, 1, 1). In this case, the MTF curve of the optical device is as follows: Fig.10 as shown in . Fig.10 A first example of an MTF curve of an optical device provided according to an embodiment of the present invention is shown.

[0085] exist Fig.10 , the horizontal axis represents the spatial frequency (cycles / mm) of the image sensor 13, and the vertical axis represents the amplitude of the modulation. In addition, in the case of (1, 1, 0, 1, 1), the solid line curve represents the MTF curve, and the dotted line dot curve represents the reference level corresponding to the condition that the ID controller 11 maintains the intensity distribution of light before and after passing therethrough.

[0086] Fig.10Comparing the solid curve and the dotted curve, it is found that in the case of (1, 1, 0, 1, 1), the MTF curve is sufficiently reduced at about 200 on the horizontal axis, which is the Nyquist frequency when the pixel pitch of the image sensor 13 is the pixel pitch in the case of 2×2 binning. This reduces the moire effect when the pixel pitch of the image sensor 13 is the pixel pitch in the case of 2×2 binning.

[0087] Likewise, the processor 14 may control the ID controller 11 to form a pattern corresponding to (1, 0, 1, 0, 1). In this case, the MTF curve of the optical device is as follows: Fig.11 as shown in . Fig.11 A second example of an MTF curve of an optical device provided according to an embodiment of the present invention is shown.

[0088] exist Fig.11 , the horizontal axis represents the spatial frequency (cycles / mm) of the image sensor 13, and the vertical axis represents the amplitude of the modulation. In addition, in the case of (1, 0, 1, 0, 1), the solid line curve represents the MTF curve, and the dotted line dot curve represents the reference level corresponding to the condition that the ID controller 11 maintains the intensity distribution of light before and after passing therethrough.

[0089] Fig.11 Comparing the solid curve and the dotted curve, it is found that in the case of (1, 0, 1, 0, 1), the MTF curve is sufficiently reduced at about 200 on the horizontal axis, which is the Nyquist frequency when the pixel pitch of the image sensor 13 is the pixel pitch in the case of 2×2 binning. In addition, the MTF curve is sufficiently reduced at about 100 on the horizontal axis, which is the Nyquist frequency when the pixel pitch of the image sensor 13 is the pixel pitch in the case of 4×4 binning. This reduces the moire effect when the pixel pitch of the image sensor 13 is the pixel pitch in the case of 2×2 binning and 4×4 binning.

[0090] (Operation of the device) Fig.12 The operation of device 10 is described. Fig.12 A flow chart for describing a method implemented by a device according to an embodiment of the present invention is shown.

[0091] In step S101, the ID controller 11 changes the intensity distribution of light passing through the ID controller 11. Specifically, the ID controller 11 is used to reduce the intensity of light passing through at least one reduction area thereof to change the intensity distribution of light entering the lens system 12 according to the pixel pitch of the image sensor 13. As described above, the image sensor 13 is a binning type image sensor with a variable pixel pitch.

[0092] In step S102 , the image sensor 13 receives the light that has passed through the lens system 12 .

[0093] In step S103 , the processor 14 generates an image based on the output signal from the image sensor 13 .

[0094] In step S104 , the processor 14 determines whether a binning operation is to be performed on the image sensor 13 .

[0095] For example, the processor 14 may determine whether an instruction to perform a merge operation is received. If the processor 14 receives an instruction to perform a merge operation, the process proceeds to step S105. If the processor 14 does not receive an instruction to perform a merge operation, the process proceeds to step S101.

[0096] In step S105 , the processor 14 controls the image sensor 13 to change its pixel pitch.

[0097] For example, when the processor 14 receives an instruction to perform 2×2 merging, the processor 14 controls the image sensor 13 to combine each set of 4 adjacent pixels into a virtual combined pixel to change the pixel pitch. In addition, when the processor 14 receives an instruction to perform 4×4 merging, the processor 14 controls the image sensor 13 to combine each set of 16 adjacent pixels into a virtual combined pixel to change the pixel pitch.

[0098] In step S106 , the processor 14 changes the pattern of the reduced area of ​​the ID controller 11 .

[0099] For example, when the pixel pitch of the image sensor 13 is 2x2 binning, the processor 14 controls the ID controller 11 to set a reduction pattern suitable for the changed pixel pitch, such as (1, 1, 0, 1, 1). In addition, when the pixel pitch of the image sensor 13 is 4x4 binning, the processor 14 controls the WF controller 11 to set a deformation pattern suitable for the changed pixel pitch, such as (1, 0, 1, 0, 1).

[0100] After the processing of step S106 is completed, the processing proceeds to step S101.

[0101] according to Fig.12 By the method shown, the intensity distribution of light entering the lens system 12 can be optimized according to the pixel pitch of the image sensor 13, so as to sufficiently reduce the MTF curve of the optical device at the Nyquist frequency related to the current pixel pitch. Reducing the MTF curve at the Nyquist frequency may reduce the moire effect that appears on the generated image. Therefore, even if the pixel pitch of the image sensor 13 is changed by the binning operation, the moire effect can be effectively reduced.

[0102] (Preferred configuration of the reduced area) Figures 13A to 15BSome preferred configurations and performances of the reduction area of ​​the ID controller 11 are described. In this case, the ID controller 11 is divided into ten annular areas, each of which has a predetermined width and can be switched between a transparent state and a reduction state.

[0103] Fig.13A A first preferred configuration of the reduced area of ​​the ID controller 11 is shown. Fig.13A In the figure, the white part represents the transparent area through which the light incident into the ID controller 11 can pass, and the black part represents the reduced area. Fig.13A The configuration shown is represented by (0, 1, 1, 0, 1, 1, 0, 1, 1, 1). In this case, according to our computer simulations, Fig.13A The MTF curve in this case becomes Fig. 13B The solid line. Fig. 13B The MTF curve corresponding to the first preferred configuration of the reduced area is shown. Fig. 13B In FIG. 1 , the dotted line represents the MTF curve in the case where all areas of the ID controller 11 are set to a transparent state.

[0104] Fig. 13B Comparing the solid line and the dotted line, it is found that in the case of (0, 1, 1, 0, 1, 1, 0, 1, 1, 1), the MTF curve is sufficiently reduced at about 200 on the horizontal axis, which is the Nyquist frequency when the pixel pitch of the image sensor 13 is the pixel pitch in the case of 2×2 binning. This effectively reduces the moire effect at least in the case of 2x2 binning.

[0105] Fig.14A A second preferred configuration of the reduced area of ​​the ID controller 11 is shown. Fig.14A In the figure, the white part represents the transparent area through which the light incident into the ID controller 11 can pass, and the black part represents the reduced area. Fig.14A The configuration shown is represented by (1, 0, 1, 1, 0, 0, 1, 0, 0, 0). In this case, according to our computer simulations, Fig.14A The MTF curve in this case becomes Fig. 14B The solid line. Fig. 14B The MTF curve for the second preferred configuration corresponding to the reduced region is shown. Fig. 14B In FIG. 1 , the dotted line represents the MTF curve in the case where all areas of the ID controller 11 are set to a transparent state.

[0106] Fig. 14BComparing the solid line and the dotted line, it is found that in the case of (1, 0, 1, 1, 0, 0, 1, 0, 0, 0), the MTF curve is sufficiently reduced at about 200 on the horizontal axis, which is the Nyquist frequency when the pixel pitch of the image sensor 13 is the pixel pitch in the case of 2×2 binning. This effectively reduces the moire effect at least in the case of 2x2 binning.

[0107] Fig.15A A third preferred configuration of the reduced area of ​​the ID controller 11 is shown. Fig.15A In the figure, the white part represents the transparent area through which the light incident into the ID controller 11 can pass, and the black part represents the reduced area. Fig.15A The configuration shown is represented by (1, 0, 0, 1, 0, 0, 1, 0, 0, 0). In this case, according to our computer simulations, Fig.15A The MTF curve in this case becomes Fig. 15B The solid line. Fig. 15B The MTF curve corresponding to the third preferred configuration of the reduced area is shown. Fig. 15B In FIG. 1 , the dotted line represents the MTF curve in the case where all areas of the ID controller 11 are set to a transparent state.

[0108] Fig. 15B Comparing the solid line and the dotted line, it is found that in the case of (1, 0, 0, 1, 0, 0, 1, 0, 0, 0), the MTF curve is sufficiently reduced at about 200 on the horizontal axis, which is the Nyquist frequency when the pixel pitch of the image sensor 13 is the pixel pitch in the case of 2×2 binning. This effectively reduces the moire effect at least in the case of 2x2 binning.

[0109] The above disclosure only discloses exemplary embodiments and is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that the above embodiments and all or part of other embodiments and modifications that can be derived according to the scope of the claims of the present invention are within the scope of the present invention.

Claims

1. An optical device, comprising: Lens system; an image sensor for receiving light passing through the lens system, wherein the image sensor is a binning type image sensor with variable pixel pitch; An intensity controller is configured to reduce the intensity of light passing through at least one of its reduced regions to change the intensity distribution of light entering the lens system according to a pixel pitch of the image sensor.

2. The optical device according to claim 1, wherein: The at least one reduction region is used to substantially reduce a modulation transfer function (MTF) curve of the optical device near a Nyquist frequency corresponding to a pixel pitch of the image sensor.

3. The optical device according to claim 1 or 2, wherein: The intensity controller is an intensity control mask for reducing the intensity of light passing through at least one reduced region thereof.

4. The optical device according to claim 3, wherein: The intensity control mask is an electrochromic device or a liquid crystal retarder.

5. The optical device according to claim 3, wherein: The intensity control mask is divided into a plurality of annular areas centered on the optical axis of the lens system, each of the plurality of annular areas being a reduced area with low light transmittance or a non-reduced area with high light transmittance.

6. A method for mitigating moire effects, comprising: reducing, by an intensity controller, the intensity of light passing through at least one reduced region of the intensity controller to change the intensity distribution of light entering the lens system according to a pixel pitch of an image sensor that is a binning-type image sensor having a variable pixel pitch; The image sensor receives light through the lens system.

7. The method according to claim 6, wherein: The method is applied to an optical device, the optical device comprising the intensity controller and the image sensor; The at least one reduction region is determined such that a modulation transfer function (MTF) curve of the optical device is substantially reduced around a Nyquist frequency corresponding to a pixel pitch of the image sensor.

8. The method according to claim 6 or 7, wherein: The intensity controller is an intensity control mask for reducing the intensity of light passing through at least one reduced region thereof.

9. The method according to claim 8, wherein: The intensity control mask is an electrochromic device or a liquid crystal retarder.

10. The method according to claim 8, wherein: The intensity control mask is divided into a plurality of annular regions centered on the optical axis of the lens system, each of the plurality of annular regions being a reduced region with low light transmittance or a non-reduced region with high light transmittance.

11. An optical device comprising: An optical device according to any one of claims 1 to 5; A processor is used to generate an image based on the output signal from the image sensor to store the image in a memory.

12. A non-transitory computer-readable storage medium for storing a program for causing a computer to execute the method according to any one of claims 6 to 10.

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