CMOS image sensor calibration method and device, CMOS image sensor module

Abstract

The present invention provides a calibration method and device for a CMOS image sensor, and a CMOS image sensor module. The calibration method for the CMOS image sensor includes: providing a CMOS image sensor module, the CMOS image sensor module including: a CMOS image sensor to be calibrated and a lens, the optical center of the lens facing the photosensitive area of ​​the CMOS image sensor; providing a light source with a fixed brightness, aimed directly above the lens; starting the CMOS image sensor to enter a normal working state; adjusting the parameters of the CMOS image sensor, when the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness, capturing the output image at this time as a test image; collecting data of the test image, and obtaining the lens attenuation compensation parameters through calculation and processing. The calibration method for a CMOS image sensor proposed by the present invention solves the problem of consistency differences in lens attenuation of a CMOS image sensor module.

Description

Technical Field

[0001] The present invention relates to the technical field of image sensors, and in particular to a calibration method and device for a CMOS image sensor, and a CMOS image sensor module. Background Art

[0002] CMOS image sensor modules all need to use lenses for imaging. The lens is a convex lens. When the incident light is focused by the lens and then incident on the surface of the CMOS image sensor, the optical path the light travels through is of different lengths. The edge area of ​​the image area receives less light intensity than the center, so the degree of brightness attenuation is also different, resulting in a brightness difference between the center and the surrounding areas of the final image.

[0003] By calibrating the image of the CMOS image sensor module and combining it with a compensation algorithm, the brightness difference between the center and the surrounding of the image can be reduced or even eliminated. In the related art, in order to overcome the above problems, an advanced optical lens with a small or zero high ray angle (CRA) is used, and an anti-reflection film is applied to the four corners of the lens. However, this method is costly and not conducive to popularization and application, and the scope of use of lenses with a small or zero high ray angle (CRA) is limited.

[0004] Alternatively, an advanced photosensitive device is used to simulate the gain of the photosensitive element in the shadow of the lens, thereby achieving a brighter output effect, so that the imaging brightness and color of the center and four corners of the lens are uniform. However, this method also has the disadvantage of high cost and is not widely used.

[0005] In actual applications, due to the consistency differences between CMOS image sensors and lenses, as well as the manufacturing errors of the module itself, the lens attenuation performance of each unit in the final CMOS image sensor module is inconsistent, and the brightness difference between the center and the surrounding of the image is also inconsistent. Therefore, even through subsequent ISP compensation, there will still be differences in the image consistency obtained between different module units. Summary of the invention

[0006] The object of the present invention is to provide a calibration method and device for a CMOS image sensor, and a CMOS image sensor module, so as to solve the technical problem of poor consistency in the calibration of images of CMOS image sensor modules in the prior art.

[0007] In order to solve the above technical problems, the present invention provides a calibration method for a CMOS image sensor, comprising:

[0008] A CMOS image sensor module is provided, wherein the CMOS image sensor module comprises: a CMOS image sensor to be calibrated and a lens, wherein the optical center of the lens is directly opposite to the photosensitive area of ​​the CMOS image sensor;

[0009] Providing a light source with fixed brightness, aiming it directly above the lens;

[0010] Start the CMOS image sensor to make it enter normal working state;

[0011] Adjusting the parameters of the CMOS image sensor, when the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness, capturing the output image at this time as a test image;

[0012] The data of the test image is collected, and lens attenuation compensation parameters are obtained through calculation and processing.

[0013] Preferably, the calculation process includes:

[0014] Divide the test image into m*n uniform regions;

[0015] The calculation is performed using a quadratic B-spline surface fitting algorithm.

[0016] Preferably, the CMOS image sensor is started up by sending a command via a host computer to enter a normal working state; the command sent by the host computer to the CMOS image sensor is parsed by a signal transmission device and then sent to the CMOS image sensor.

[0017] Preferably, by adjusting the exposure and gain parameters of the CMOS image sensor, an output image is obtained in which the brightness of the central area is 1 / 2 to 2 / 3 of the full-scale brightness.

[0018] Preferably, the light source is a uniform light source with a color temperature of 5100K.

[0019] Preferably, the CMOS image sensor module further comprises a flexible circuit board, a peripheral circuit, a voice coil motor and a connector, and the flexible circuit board is suitable for electrically connecting the peripheral circuit, the voice coil motor, the connector and the CMOS image sensor.

[0020] The technical solution of the present invention also provides a calibration device for a CMOS image sensor, comprising:

[0021] A CMOS image sensor module, the CMOS image sensor module comprising: a CMOS image sensor and a lens, the optical center of the lens facing the photosensitive area of ​​the CMOS image sensor;

[0022] A light source, aimed directly above the lens, suitable for providing a light source of fixed brightness;

[0023] The host computer is suitable for issuing instructions to allow the CMOS image sensor to enter a normal working state and adjust the parameters of the CMOS image sensor. When the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness, the output image at this time is captured as a test image, and data of the test image is collected to obtain lens attenuation compensation parameters through calculation and processing.

[0024] Preferably, the host computer comprises a calculation processing unit, and the calculation processing unit is suitable for dividing the test image into m*n uniform areas; and performing calculations by a quadratic B-spline surface fitting algorithm.

[0025] Preferably, the host computer is connected to the signal transmission device via USB, and performs signal interaction via USB protocol; the command sent by the host computer to the CMOS image sensor is parsed by the signal transmission device and then sent to the CMOS image sensor.

[0026] Preferably, the host computer is suitable for obtaining an output image whose central area brightness is 1 / 2 to 2 / 3 of the full-scale brightness by adjusting the exposure and gain parameters of the CMOS image sensor.

[0027] Preferably, the light source is a uniform light source with a color temperature of 5100K.

[0028] The technical solution of the present invention also provides a calibration method for a CMOS image sensor, comprising:

[0029] Providing a CMOS image sensor module to be calibrated, wherein the CMOS image sensor module comprises a CMOS image sensor to be calibrated and a storage unit;

[0030] The lens attenuation compensation parameters obtained by the above method are burned into the storage unit of the CMOS image sensor module.

[0031] Preferably, the storage unit is an OTP embedded in the CMOS image sensor, or an external EEPROM.

[0032] The technical solution of the present invention also provides a CMOS image sensor module, comprising:

[0033] CMOS image sensor and storage unit to be calibrated;

[0034] The storage unit includes a lens attenuation compensation parameter unit, and the lens attenuation compensation parameter unit is suitable for burning in the lens attenuation compensation parameters by the method as described above;

[0035] The CMOS image sensor is suitable for reading the lens attenuation compensation parameter from the lens attenuation compensation parameter unit.

[0036] Preferably, the CMOS image sensor module further includes a peripheral circuit, a voice coil motor, a connector, a flexible circuit board and a lens.

[0037] Preferably, the storage unit is an OTP embedded in the CMOS image sensor or an external EEPROM.

[0038] Compared with the prior art, the CMOS image sensor calibration method and device, and CMOS image sensor module provided by the technical solution of the present invention have the following beneficial effects:

[0039] The technical solution of the present invention provides a calibration method and device for a CMOS image sensor, which solves the problem of consistency differences in lens attenuation of a CMOS image sensor module.

[0040] The technical solution of the present invention provides a CMOS image sensor module and performs lens attenuation compensation calibration on the module monomer, so that the lens attenuation consistency of the final output images of different modules is improved, providing a more consistent input image for subsequent ISP processing.

[0041] In the calibration method of a CMOS image sensor described in the present invention, lens attenuation compensation calibration is realized fully automatically with one button, thereby improving measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flowchart of a calibration method for a CMOS image sensor in an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the structure of a CMOS image sensor module in an embodiment of the present invention;

[0044] Figure 3 to Figure 4 A schematic diagram of a calculation method in a proofreading method in an embodiment provided by the present invention;

[0045] Figure 5 A schematic diagram showing the image brightness comparison before and after correction of the same image information in the embodiment provided by the present invention;

[0046] Figure 6 A schematic diagram of the structure of a calibration device for a CMOS image sensor in an embodiment of the present invention;

[0047] Figure 7 The present invention provides a flowchart of a calibration method for a CMOS image sensor in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0049] Secondly, the present invention is described in detail using schematic diagrams. When describing the embodiments of the present invention in detail, for the convenience of explanation, the schematic diagrams are only examples and should not limit the scope of protection of the present invention.

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the following is a diagram of the present invention with reference to the accompanying drawings. Figures 1 to 7 The calibration method of the CMOS image sensor of the present invention is described in detail.

[0051] refer to Figure 1 As shown, an embodiment of the present invention provides a calibration method for a CMOS image sensor, comprising:

[0052] Step S100: providing a CMOS image sensor module 63, wherein the CMOS image sensor module 63 comprises: a CMOS image sensor 36 to be calibrated and a lens 31 facing a photosensitive area of ​​the CMOS image sensor;

[0053] Step S200: providing a light source with a fixed brightness, and aligning it directly above the lens 31;

[0054] Step S300: Start the CMOS image sensor 36 to enter a normal working state;

[0055] Step S400: adjusting the parameters of the CMOS image sensor 36, and when the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness, capturing the output image at this time as a test image;

[0056] Step S500: collecting data of the test image, and obtaining lens attenuation compensation parameters through calculation and processing.

[0057] Specifically, in this embodiment, the calibration method of the CMOS image sensor is performed as follows:

[0058] Execute step S100: provide a CMOS image sensor module 63, wherein the CMOS image sensor module 63 comprises: a CMOS image sensor 36 to be calibrated and a lens 31 facing a photosensitive area of ​​the CMOS image sensor;

[0059] Specifically, in this embodiment, the CMOS image sensor 36 includes a photosensitive area.

[0060] Specifically, in this embodiment, the lens 31 may be a lens from lens manufacturers such as LARGAN and SUNNY.

[0061] The CMOS image sensor module 63 further includes a storage unit.

[0062] refer to Figure 2 As shown, in a specific embodiment, the CMOS image sensor module 63 is composed of a CMOS image sensor 36, a connector 35, a peripheral circuit, a lens 31, a voice coil motor 32, a flexible circuit board 34, and a connector 35; the flexible circuit board 34 is a carrier, the CMOS image sensor 36 and the connector are welded on the flexible circuit board 34, the voice coil motor 32 is connected to the flexible circuit board 34 by black glue, the lens 31 and the voice coil motor 32 are connected by threads, and the lens 31 realizes the focusing function through the voice coil motor 32; the connector is an interface connected to the outside, the flexible circuit board is a carrier, and provides signal connection and transmission between the connector and the CMOS image sensor 36.

[0063] The storage unit is an OTP (One Time Programmable) microcontroller embedded in the CMOS image sensor 36 chip or an external EEPROM (Electrically Erasable Programmable read only memory).

[0064] Execute step S200: provide a light source with fixed brightness, and aim it at the top of the lens;

[0065] The light source is a constant uniform light source, and the color temperature of the light source is 5000K~5200K. Because this color temperature is relatively moderate, and because in actual working or living environments, there are more color temperatures of 5000K~5200K, such as office environments under fluorescent lights, this color temperature light source range is selected.

[0066] The light source is directed to illuminate the top of the lens 31 in such a manner that the light from the center area of ​​the light source is projected onto the lens substantially along the optical axis of the lens, so that the light received by the upper surface of the lens is relatively uniform and consistent.

[0067] The lower surface of the lens is aligned with the photosensitive area surface of the CMOS image sensor 36. Due to the principle of the lens, when the relatively uniform incident light is focused by the lens 31 and then incident on the photosensitive area surface of the CMOS image sensor 36, the light path lengths of the light are different, and the edge area of ​​the image area receives less light intensity than the center, so the degree of brightness attenuation is also different, resulting in a brightness difference between the center and the surrounding of the final image.

[0068] Step S300: Start the CMOS image sensor 36 to enter a normal working state;

[0069] Specifically, in this embodiment, the host computer sends a command to start the CMOS image sensor 36, so that it enters a normal working state, the photosensitive area can normally receive light, and the CMOS image sensor 36 can convert the light received by the photosensitive area into a digital signal, that is, a picture output.

[0070] Specifically, in this embodiment, the command sent by the host computer to the CMOS image sensor 36 is parsed by the signal transmission device 62 and then sent to the CMOS image sensor 36 .

[0071] Execute step S400: adjust the parameters of the CMOS image sensor 36, and when the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness, capture the output image at this time as a test image;

[0072] Preferably, the image brightness can be adjusted by adjusting the exposure and gain parameters of the CMOS image sensor 36, thereby obtaining an output image in which the brightness of the central area is 1 / 2 to 2 / 3 of the full-scale brightness.

[0073] When the CMOS image sensor is in normal use, the brightness of the light in the external environment is mostly concentrated in the middle range of the CMOS image sensor. Therefore, in this embodiment, the output image when the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness is set as the test image. In simple terms, the image brightness is above medium, which can make the calculation output result more accurate. If the image brightness is too low, the calculation output value will be small, and the accuracy of the calculation result will be reduced; if the image brightness is too high, there is a risk of reaching the full scale, and the accuracy of the calculation result will also be reduced.

[0074] Preferably, in this embodiment, an output image when the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness is set as the test image.

[0075] Execute step S500: collect data of the test image, and obtain lens attenuation compensation parameters through calculation and processing.

[0076] Preferably, reference Figure 3~Figure 4 As shown, in this embodiment, the calculation process includes:

[0077] The test image is divided into m*n uniform regions; for each region, according to its corresponding coordinate position (x, y), the control point data value of the current region is calculated by the quadratic B-spline surface matrix algorithm.

[0078]

[0079] refer to Figure 5 As shown in the figure, the image brightness of the same image information in the X, Y and Z directions before and after correction is shown. Among them, X is the row direction, Y is the column direction, and Z is the diagonal direction. It can be seen from the figure that the image brightness in the X, Y or Z direction of the same image information before correction is bright in the center and dark on both sides, while after correction, the brightness near the two sides in the X, Y or Z direction is improved compared with that before correction.

[0080] In addition, refer to Figure 6 , which is a structural block diagram of a CMOS image sensor calibration device provided in an embodiment of the technical solution provided by the present invention. Specifically, the CMOS image sensor calibration device includes: a host computer 61, a CMOS image sensor module 63 and a light source 64. The host computer 61 and the CMOS image sensor module 63 perform signal transmission through a signal transmission device 62.

[0081] The CMOS image sensor module 63 includes: a CMOS image sensor 36 and a lens facing the photosensitive area of ​​the CMOS image sensor; Figure 2 As shown, in a specific embodiment, the CMOS image sensor module 63 is composed of a CMOS image sensor 36 and its peripheral circuits, a lens 31, a voice coil motor 32, a flexible circuit board 34, and a connector 35; the flexible circuit board 34 is a carrier, the CMOS image sensor 36 and the connector are welded on the flexible circuit board 34, the voice coil motor 32 is connected to the flexible circuit board 34 by black glue, the lens 31 and the voice coil motor 32 are connected by threads, and the lens 31 realizes the focusing function through the voice coil motor 32; the connector is an interface connected to the outside, the flexible circuit board is a carrier, and provides signal connection and transmission between the connector and the CMOS image sensor 36.

[0082] The light source 64 is aligned directly above the lens of the CMOS image sensor module 63 and is suitable for providing a light source with a fixed brightness;

[0083] The host computer 61 is suitable for issuing instructions to allow the CMOS image sensor to enter a normal working state and adjust the parameters of the CMOS image sensor. When the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness, the output image at this time is captured as a test image, and data of the test image is collected to obtain lens attenuation compensation parameters through calculation and processing.

[0084] Preferably, the host computer 61 includes a computing unit, which is suitable for dividing the test image into m*n uniform regions. Figure 3~Figure 4As shown, each region calculates the control point data value of the current region according to its corresponding coordinate position (x, y) through the quadratic B-spline surface matrix algorithm.

[0085]

[0086] Preferably, the host computer 61 is connected to the signal transmission device 62 via USB and performs signal interaction via USB protocol; the command sent by the host computer 61 to the CMOS image sensor 36 is parsed by the signal transmission device 62 and then sent to the CMOS image sensor 36 .

[0087] Preferably, the host computer 61 is adapted to adjust the exposure and gain parameters of the CMOS image sensor 36 to obtain an output image whose central area brightness is 1 / 2 to 2 / 3 of the full-scale brightness.

[0088] Preferably, the light source is a uniform light source with a color temperature of 5100K.

[0089] In addition, refer to Figure 7 As shown, in this embodiment, a calibration method for a CMOS image sensor is also provided, comprising:

[0090] Step S910: providing a CMOS image sensor module 63 to be calibrated, wherein the CMOS image sensor module comprises a CMOS image sensor to be calibrated and a storage unit;

[0091] Step S920: burning the lens attenuation compensation parameters obtained by the calibration method of the CMOS image sensor into the storage unit of the CMOS image sensor module.

[0092] In the embodiment provided by the technical solution of the present invention, the CMOS image sensor module has its own storage unit and does not require an external storage device, thus saving space and cost.

[0093] Preferably, the storage unit is an OTP embedded in the CMOS image sensor, or an external EEPROM, to ensure that data is not lost after power failure.

[0094] In addition, in this embodiment, a CMOS image sensor module is also provided, comprising: a CMOS image sensor to be calibrated and a storage unit;

[0095] The storage unit includes a lens attenuation compensation parameter unit, and the lens attenuation compensation parameter unit is suitable for burning in the lens attenuation compensation parameters by the method as described above;

[0096] The CMOS image sensor is suitable for reading the lens attenuation compensation parameter from the lens attenuation compensation parameter unit.

[0097] Preferably, the CMOS image sensor module further comprises a flexible circuit board and a lens. The implementation of other structures of the CMOS image sensor module is similar to the above.

[0098] Preferably, the storage unit is an OTP embedded in the CMOS image sensor chip or an external EEPROM.

[0099] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A calibration method for a CMOS image sensor, characterized in that: include: A CMOS image sensor module is provided, wherein the CMOS image sensor module comprises: a CMOS image sensor to be calibrated and a lens, wherein the optical center of the lens is directly opposite to the photosensitive area of ​​the CMOS image sensor; Providing a light source with fixed brightness, aiming it directly above the lens; Start the CMOS image sensor to make it enter normal working state; Adjusting the parameters of the CMOS image sensor, when the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness, capturing the output image at this time as a test image; The data of the test image is collected, and lens attenuation compensation parameters are obtained through calculation and processing.

2. The calibration method of a CMOS image sensor according to claim 1, wherein: The calculation process includes: Divide the test image into m*n uniform regions; The calculation is performed using a quadratic B-spline surface fitting algorithm.

3. The calibration method of a CMOS image sensor according to claim 1, wherein: The CMOS image sensor is started by sending a command through a host computer to enter a normal working state; the command sent by the host computer to the CMOS image sensor is parsed by a signal transmission device and then sent to the CMOS image sensor.

4. The calibration method of a CMOS image sensor according to claim 1, wherein: By adjusting the exposure and gain parameters of the CMOS image sensor, an output image with a central area brightness of 1 / 2 to 2 / 3 of the full-scale brightness is obtained.

5. The calibration method of a CMOS image sensor according to claim 1, wherein: The light source is a uniform light source with a color temperature of 5000K~5200K.

6. The calibration method of a CMOS image sensor according to claim 1, wherein: The CMOS image sensor module also includes a flexible circuit board, a peripheral circuit, a voice coil motor and a connector, and the flexible circuit board is suitable for electrically connecting the peripheral circuit, the voice coil motor, the connector and the CMOS image sensor.

7. A calibration device for a CMOS image sensor, characterized in that: include: A CMOS image sensor module, the CMOS image sensor module comprising: a CMOS image sensor and a lens, the optical center of the lens facing the photosensitive area of ​​the CMOS image sensor; A light source, aimed directly above the lens, suitable for providing a light source of fixed brightness; The host computer is suitable for issuing instructions to allow the CMOS image sensor to enter a normal working state and adjust the parameters of the CMOS image sensor. When the brightness of the central area of ​​the output image is 1 / 2 to 2 / 3 of the full-scale brightness, the output image at this time is captured as a test image, and data of the test image is collected to obtain lens attenuation compensation parameters through calculation and processing.

8. The calibration device for a CMOS image sensor according to claim 7, wherein: The host computer comprises a calculation processing unit, and the calculation processing unit is suitable for dividing the test image into m*n uniform areas; and performing calculations by a quadratic B-spline surface fitting algorithm.

9. The calibration device for a CMOS image sensor according to claim 8, wherein: The host computer is connected to the signal transmission device via USB and performs signal interaction via the USB protocol; the command sent by the host computer to the CMOS image sensor is parsed by the signal transmission device and then sent to the CMOS image sensor.

10. The calibration device for a CMOS image sensor according to claim 9, wherein: The host computer is suitable for obtaining an output image whose central area brightness is 1 / 2 to 2 / 3 of the full-scale brightness by adjusting the exposure and gain parameters of the CMOS image sensor.

11. The calibration device for a CMOS image sensor according to claim 10, wherein: The light source is a uniform light source with a color temperature of 5000K~5200K.

12. A calibration method for a CMOS image sensor, characterized in that: include: Providing a CMOS image sensor module to be calibrated, wherein the CMOS image sensor module comprises a CMOS image sensor to be calibrated and a storage unit; The lens attenuation compensation parameters obtained by the method according to claim 1 are burned into the storage unit of the CMOS image sensor module.

13. The calibration method of a CMOS image sensor according to claim 12, wherein: include: The storage unit is an OTP embedded in the CMOS image sensor or an external EEPROM.

14. A CMOS image sensor module, characterized in that: include: CMOS image sensor and storage unit to be calibrated; The storage unit includes a lens attenuation compensation parameter unit, and the lens attenuation compensation parameter unit is suitable for burning in lens attenuation compensation parameters by the method according to claim 1; The CMOS image sensor is suitable for reading the lens attenuation compensation parameter from the lens attenuation compensation parameter unit.

15. The CMOS image sensor module according to claim 14, wherein: The CMOS image sensor module also includes a peripheral circuit, a voice coil motor, a connector, a flexible circuit board and a lens.

16. The CMOS image sensor module according to claim 14, wherein: The storage unit is an OTP embedded in the CMOS image sensor or an external EEPROM.

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