CN112752041A - CMOS image sensor correction method, system and image processing equipment - Google Patents
CMOS image sensor correction method, system and image processing equipment Download PDFInfo
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Abstract
The invention provides a method and a system for correcting a CMOS image sensor and image processing equipment, wherein the method comprises the following steps: after the CMOS image sensor is powered on, acquiring initial environment temperature; acquiring an image required for correction, and calculating a correction parameter according to the image required for correction; obtaining an ambient temperature change value; judging whether the ambient temperature change value is greater than or equal to a preset ambient temperature change value or not; if so, acquiring the image required by correction again, and recalculating the correction parameters to obtain corrected correction parameters; and correcting the CMOS image sensor according to the corrected correction parameters. According to the invention, in the working process of the equipment, the correction parameters of the CMOS image sensor can be corrected according to the change condition of the environmental temperature, and the accuracy and reliability of the correction parameters are improved, so that the temperature adaptability of the CMOS image sensor is improved, the correction result is accurate and reliable, the column noise is effectively eliminated, and the image quality is improved.
Description
Technical Field
The present invention relates to the field of image processing technologies, and in particular, to a method and a system for correcting a CMOS image sensor, and an image processing apparatus.
Background
At present, the mainstream processing structure of a CMOS (Complementary Metal Oxide Semiconductor) image sensor system adopts a column-shared processing circuit, i.e. each column of pixels shares one set of signal processing circuit, and the most obvious problem of the structure is the column noise problem caused by mismatch of the column-shared processing circuit, which is called column fixed pattern noise. Column fixed pattern noise is clearly observed in an uncorrected CMOS image sensor, and appears as "vertical lines" of varying brightness on the image. Therefore, in use, each column of the CMOS image sensor needs to be corrected to eliminate these "vertical lines", i.e., to eliminate column fixed pattern noise.
At present, the related technology for column correction of a CMOS image sensor mainly acquires correction parameters at a debugging stage, then stores the correction parameters in a memory, and reads the correction parameters from the memory during actual use, and then corrects the CMOS image sensor.
However, the method for acquiring and storing the sensor correction parameters in advance is not applicable to occasions with obvious temperature changes, and the correction parameters are affected by the temperature changes, so that the correction result is not accurate, and the quality of the image is affected; in addition, the method of acquiring and storing the correction parameters in advance may cause the correction parameters to change after the device is used for a period of time, which may also cause inaccurate correction results and affect the quality of the image.
Disclosure of Invention
The present invention is directed to solving at least one of the above problems.
Therefore, an object of the present invention is to provide a method for correcting a CMOS image sensor, which can correct a correction parameter of the CMOS image sensor according to a change of an ambient temperature during an operation of a device, so as to improve accuracy and reliability of the correction parameter, thereby improving temperature adaptability of the CMOS image sensor, further making a correction result accurate and reliable, thereby effectively eliminating column noise and improving image quality.
To this end, a second object of the present invention is to provide a calibration system for a CMOS image sensor.
To this end, a third object of the present invention is to propose an image processing apparatus.
In order to achieve the above object, an embodiment of a first aspect of the present invention proposes a calibration method for a CMOS image sensor, including the steps of: after the CMOS image sensor is powered on, acquiring initial environment temperature; acquiring an image required for correction, and calculating a correction parameter according to the image required for correction; detecting the ambient temperature in real time, and obtaining an ambient temperature change value by combining the initial ambient temperature; judging whether the environmental temperature change value is larger than or equal to a preset environmental temperature change value or not; if so, acquiring the image required by correction again, and recalculating the correction parameters to obtain corrected correction parameters; and correcting the CMOS image sensor according to the corrected correction parameters.
According to the correction method of the CMOS image sensor, the correction parameters of the CMOS image sensor can be corrected according to the environment temperature change condition in the working process of equipment, the accuracy and the reliability of the correction parameters are improved, the temperature adaptability of the CMOS image sensor is improved, the correction result is accurate and reliable, column noise is effectively eliminated, and the image quality is improved.
In addition, the correction method of the CMOS image sensor according to the above embodiment of the present invention may further have the following additional technical features:
in some examples, the image required for correction includes a first image output by the CMOS image sensor with a luminance higher than a preset luminance and a second image output by the CMOS image sensor with a luminance lower than the preset luminance, and the calculating of the correction parameter from the image required for correction includes: calculating the average value of pixels of each column of the first image and the second image; calculating the pixel average value of the first image and the second image; and calculating the correction parameter according to the pixel average value of each column of the first image and the second image and the pixel average value of the first image and the second image.
In some examples, the modified correction parameters include a correction gain and a correction offset, and the correcting the CMOS image sensor according to the modified correction parameters includes:
y′i＝Ki×yi+bi
wherein i is any column in the CMOS image sensor, and yiImage data to be corrected, y ', acquired for a CMOS image sensor'iFor corrected image data, KiFor the correction gain, biIs the correction bias.
In some examples, the correction gain is calculated by:
where i is any column in the CMOS image sensor, and KiFor the purpose of the said correction gain, the gain is,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
In some examples, the correction bias is calculated by:
where i is any column in the CMOS image sensor, biIn order to correct the offset, the offset is corrected,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
In order to achieve the above object, an embodiment of a second aspect of the present invention proposes a correction system of a CMOS image sensor, including: the acquisition module is used for acquiring the initial environment temperature after the CMOS image sensor is electrified; the calculation module is used for acquiring an image required by correction and calculating a correction parameter according to the image required by correction; the detection module is used for detecting the ambient temperature in real time and obtaining an ambient temperature change value by combining the initial ambient temperature; the judging module is used for judging whether the environment temperature change value is larger than or equal to a preset environment temperature change value; the correction module is used for controlling the calculation module to acquire an image required by correction again and calculating correction parameters again to obtain corrected correction parameters when the ambient temperature change value is larger than or equal to a preset ambient temperature change value; and the correction module is used for correcting the CMOS image sensor according to the corrected correction parameters.
According to the correction system of the CMOS image sensor, provided by the embodiment of the invention, the correction parameters of the CMOS image sensor can be corrected according to the environment temperature change condition in the working process of equipment, so that the accuracy and the reliability of the correction parameters are improved, the temperature adaptability of the CMOS image sensor is improved, the correction result is accurate and reliable, the column noise is effectively eliminated, and the image quality is improved.
In addition, the correction system of the CMOS image sensor according to the above embodiment of the present invention may further have the following additional technical features:
in some examples, the image required for correction includes a first image output by the CMOS image sensor with a luminance higher than a preset luminance and a second image output by the CMOS image sensor with a luminance lower than the preset luminance, and the calculation module calculates the correction parameter according to the image required for correction, including: calculating the average value of pixels of each column of the first image and the second image; calculating the pixel average value of the first image and the second image; and calculating the correction parameter according to the pixel average value of each column of the first image and the second image and the pixel average value of the first image and the second image.
In some examples, the modified correction parameters include a correction gain and a correction offset, and the correction module corrects the CMOS image sensor according to the modified correction parameters, including:
y′i＝Ki×yi+bi
wherein i is any column in the CMOS image sensor, and yiImage data to be corrected, y ', acquired for a CMOS image sensor'iFor corrected image data, KiFor the correction gain, biIs the correction bias.
In some examples, the correction gain is calculated by:
where i is any column in the CMOS image sensor, and KiFor the purpose of the said correction gain, the gain is,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
In some examples, the correction bias is calculated by:
where i is any column in the CMOS image sensor, biIn order to correct the offset, the offset is corrected,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
In order to achieve the above object, an embodiment of a third aspect of the present invention proposes an image processing apparatus including: a CMOS image sensor; and the correction system of the CMOS image sensor according to the above embodiment of the present invention.
According to the image processing equipment provided by the embodiment of the invention, the correction parameters of the CMOS image sensor can be corrected according to the change condition of the environmental temperature in the working process of the equipment, so that the accuracy and the reliability of the correction parameters are improved, the temperature adaptability of the CMOS image sensor is improved, the correction result is accurate and reliable, the column noise is effectively eliminated, and the image quality is improved.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
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The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flowchart of a calibration method of a CMOS image sensor according to an embodiment of the present invention;
fig. 2 is a block diagram of a correction system of a CMOS image sensor according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
A correction method, system, and image processing apparatus of a CMOS image sensor according to embodiments of the present invention are described below with reference to the accompanying drawings.
Fig. 1 is a flowchart of a calibration method of a CMOS image sensor according to an embodiment of the present invention. As shown in fig. 1, the method for correcting a CMOS image sensor includes the steps of:
step S1: after the CMOS image sensor is powered on, the initial environment temperature is obtained. The initial ambient temperature is the current ambient temperature corresponding to the CMOS image sensor when being powered on.
Step S2: an image required for correction is acquired, and correction parameters are calculated from the image required for correction.
In one embodiment of the invention, the images required for correction include a first image output by the CMOS image sensor with a luminance higher than a preset luminance and a second image output by the CMOS image sensor with a luminance lower than the preset luminance, i.e., the luminance of the first image is higher and the luminance of the second image is lower. Then, calculating a correction parameter according to the image required for correction, including: calculating the average value of pixels of each column of the first image and the second image; calculating the pixel average value of the first image and the second image; and calculating to obtain a correction parameter according to the pixel average value of each column of the first image and the second image and the pixel average value of the first image and the second image.
In a specific embodiment, the method for acquiring the image required for correction may be: when the device turns on the light source, the CMOS image sensor outputs a first image, and when the device turns off the light source, the CMOS image sensor outputs a second image.
In a specific embodiment, the method for acquiring the image required for correction may further include: the first image and the second image are two pictures with different brightness, wherein,
1. the lower brightness image acquisition mode is:
and turning off the LED light source, setting the camera to enter a dark image acquisition mode, setting relevant parameters, and acquiring lower-brightness image data, namely a second image.
2. The higher brightness image acquisition mode is:
and (3) turning on an LED light source, enabling the LED to emit blue light, shooting a picture, checking the picture, judging whether the obtained image meets the threshold value and the uniformity requirement of a brighter image, if so, determining the picture to be a first image, and starting to calculate a correction parameter according to the first image, if not, adjusting the illumination intensity of the LED, and repeating the steps 1 and 2 until the first image meeting the requirement is obtained.
Further, the correction parameters include a correction gain and a correction offset, wherein,
the calculation method of the correction gain is as follows:
where i is any column in the CMOS image sensor, and KiFor the purpose of the said correction gain, the gain is,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
The calculation method of the correction offset is as follows:
where i is any column in the CMOS image sensor, biIn order to correct the offset, the offset is corrected,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
As a specific example, the correction to the CMOS image sensor may include column correction or dot correction.
The following describes a method for calculating a correction parameter for column correction of a CMOS image sensor, and specifically includes:
a CMOS image sensor outputs a first image;
2. calculating the average value of the pixels of the ith column of the first image
And the pixel average value of the first image
The CMOS image sensor outputs a second image;
4. calculating the average value of the pixels of the i columns of the second image
And the pixel average value of the second image
Wherein i is any column in the CMOS image sensor, j is any row in the CMOS image sensor, a is the total number of columns in the CMOS image sensor, and B is the total number of rows in the CMOS image sensor.
The following describes a method for calculating correction parameters for point correction of a CMOS image sensor, and specifically includes:
a CMOS image sensor outputs a first image;
2. calculating an average value of pixels of the first image
The CMOS image sensor outputs a second image;
4. calculating the pixel average value of the second image
Wherein i is any column in the CMOS image sensor, j is any row in the CMOS image sensor, a is the total number of columns in the CMOS image sensor, and B is the total number of rows in the CMOS image sensor.
Further, Ki,jA correction gain for said point (j, i); bi,jA correction bias for said (j, i) point;
wherein, Yi,j(xH) Is the pixel value of the (j, i) point in the first image;
is the pixel average of the first image; y isi,j(xL) Is the pixel value of the (j, i) point in the second image;
is the average value of the pixels of the second image.
In order to save memory space and reduce the amount of computation, column correction may be used instead of dot correction in general in the case of not demanding image quality in combination with the physical characteristics of the CMOS image sensor (the same signal processing circuit is used for the pixels in the same column, and therefore the correction parameters for the pixels in the same column are substantially the same).
Step S3: and detecting the ambient temperature in real time, and combining the initial ambient temperature to obtain an ambient temperature change value. Namely, in the working process of the equipment, the environmental temperature is detected in real time, and the corresponding environmental temperature change value is obtained by combining the initial environmental temperature detected when the equipment is powered on.
Step S4: and judging whether the ambient temperature change value is greater than or equal to a preset ambient temperature change value. Specifically, the preset ambient temperature change value is a critical value for determining whether the ambient temperature change is large, if the ambient temperature change value is larger than or equal to the preset ambient temperature change value, the ambient temperature change value is large, the ambient temperature change is obvious, that is, the correction parameter needs to be corrected, otherwise, the ambient temperature change value is small, the ambient temperature change is not obvious, and the correction parameter does not need to be corrected.
Step S5: if the ambient temperature change value is larger than or equal to the preset ambient temperature change value, the image required by correction is obtained again, and the correction parameter is calculated again to obtain the corrected correction parameter, so that the condition that the correction parameter is inaccurate due to large ambient temperature change and long service time is avoided, the temperature adaptability of the CMOS image sensor is enhanced, the accuracy and the reliability of the correction parameter are improved, and the image quality is further improved.
Step S6: and correcting the CMOS image sensor according to the corrected correction parameters.
In one embodiment of the present invention, the correcting the CMOS image sensor according to the corrected correction parameter includes:
y′i＝Ki×yi+bi
wherein, yiThe image correction method comprises the steps of acquiring image data to be corrected, namely original image data, for a CMOS image sensor; y'iFor corrected image data, KiTo correct the gain, biTo correct for the offset.
Specifically, the correction parameter K is obtained by the calculation method of the correction parameteriAnd biThen, when the CMOS image sensor newly acquires the image data, the original data y of each column of imageiFrom formula y'i＝Ki×yi+biCorrected image data y 'are obtained after correction'iCorrected image data y'iNamely, the column noise of the image can be basically eliminated, and the image quality is higher.
The method comprises the steps of acquiring environmental temperature data in real time after the equipment normally operates, judging whether the environmental temperature changes to a threshold value (namely a preset temperature change value) which needs to be corrected again, when the environmental temperature reaches the threshold value which needs to be corrected, correcting and storing the parameters again by the equipment, namely, acquiring an image which needs to be corrected again, recalculating a new correction parameter according to the image which needs to be corrected, storing the new correction parameter, and finally correcting the CMOS image sensor according to the new correction parameter, so that the condition that the correction parameter is inaccurate due to large environmental temperature change and long service time is avoided, the temperature adaptability of the CMOS image sensor is enhanced, the accuracy and the reliability of the correction parameter are improved, and the image quality is improved.
According to the correction method of the CMOS image sensor, the correction parameters of the CMOS image sensor can be corrected according to the environment temperature change condition in the working process of equipment, the accuracy and the reliability of the correction parameters are improved, the temperature adaptability of the CMOS image sensor is improved, the correction result is accurate and reliable, column noise is effectively eliminated, and the image quality is improved.
The invention further provides a correction system of the CMOS image sensor.
Fig. 2 is a block diagram of a correction system of a CMOS image sensor according to an embodiment of the present invention. As shown in fig. 2, the calibration system 100 of the CMOS image sensor includes: an acquisition module 110, a calculation module 120, a detection module 130, a determination module 140, a modification module 50, and a correction module 160.
The obtaining module 110 is configured to obtain an initial ambient temperature after the CMOS image sensor is powered on. The initial ambient temperature is the current ambient temperature corresponding to the CMOS image sensor when being powered on.
The calculation module 120 is configured to obtain an image required for correction, and calculate a correction parameter according to the image required for correction.
In one embodiment of the invention, the images required for correction include a first image output by the CMOS image sensor when the luminance is higher than the preset luminance and a second image output by the CMOS image sensor when the luminance is lower than the preset luminance, that is, the luminance of the first image is higher and the luminance of the second image is lower. The calculation module 120 calculates correction parameters according to the image required for correction, including: calculating the average value of pixels of each column of the first image and the second image; calculating the pixel average value of the first image and the second image; and calculating to obtain a correction parameter according to the pixel average value of each column of the first image and the second image and the pixel average value of the first image and the second image.
In a specific embodiment, the method for acquiring the image required for correction may be: when the device turns on the light source, the CMOS image sensor outputs a first image, and when the device turns off the light source, the CMOS image sensor outputs a second image.
In a specific embodiment, the method for acquiring the image required for correction may further include: the first image and the second image are two pictures with different brightness, wherein,
1. the lower brightness image acquisition mode is:
and turning off the LED light source, setting the camera to enter a dark image acquisition mode, setting relevant parameters, and acquiring lower-brightness image data, namely a second image.
2. The higher brightness image acquisition mode is:
and (3) turning on an LED light source, enabling the LED to emit blue light, shooting a picture, checking the picture, judging whether the obtained image meets the threshold value and the uniformity requirement of a brighter image, if so, determining the picture to be a first image, and starting to calculate a correction parameter according to the first image, if not, adjusting the illumination intensity of the LED, and repeating the steps 1 and 2 until the first image meeting the requirement is obtained.
Further, the correction parameters include a correction gain and a correction offset, wherein,
the calculation method of the correction gain is as follows:
where i is any column in the CMOS image sensor, and KiFor the purpose of the said correction gain, the gain is,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
The calculation method of the correction offset is as follows:
where i is any column in the CMOS image sensor, biIn order to correct the offset, the offset is corrected,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
As a specific example, the correction to the CMOS image sensor may include column correction or dot correction.
The following describes a method for calculating a correction parameter for column correction of a CMOS image sensor, and specifically includes:
a CMOS image sensor outputs a first image;
2. calculating the average value of the pixels of the ith column of the first image
And the pixel average value of the first image
The CMOS image sensor outputs a second image;
4. calculating the average value of the pixels of the i columns of the second image
And the pixel average value of the second image
Wherein i is any column in the CMOS image sensor, j is any row in the CMOS image sensor, a is the total number of columns in the CMOS image sensor, and B is the total number of rows in the CMOS image sensor.
The following describes a method for calculating correction parameters for point correction of a CMOS image sensor, and specifically includes:
a CMOS image sensor outputs a first image;
2. calculating an average value of pixels of the first image
The CMOS image sensor outputs a second image;
4. calculating the pixel average value of the second image
Wherein i is any column in the CMOS image sensor, j is any row in the CMOS image sensor, a is the total number of columns in the CMOS image sensor, and B is the total number of rows in the CMOS image sensor.
Further, Ki,jA correction gain for said point (j, i); bi,jA correction bias for said (j, i) point;
wherein, Yi,j(xH) Is the pixel value of the (j, i) point in the first image;
is the pixel average of the first image; y isi,j(xL) Is the pixel value of the (j, i) point in the second image;
is the average value of the pixels of the second image.
In order to save memory space and reduce the amount of computation, column correction may be used instead of dot correction in general in the case of not demanding image quality in combination with the physical characteristics of the CMOS image sensor (the same signal processing circuit is used for the pixels in the same column, and therefore the correction parameters for the pixels in the same column are substantially the same).
The detection module 130 is configured to detect the ambient temperature in real time, and obtain an ambient temperature variation value by combining the initial ambient temperature. Namely, in the working process of the equipment, the environmental temperature is detected in real time, and the corresponding environmental temperature change value is obtained by combining the initial environmental temperature detected when the equipment is powered on.
The determining module 140 is configured to determine whether the ambient temperature variation value is greater than or equal to a preset ambient temperature variation value. Specifically, the preset ambient temperature change value is a critical value for determining whether the ambient temperature change is large, if the ambient temperature change value is larger than or equal to the preset ambient temperature change value, the ambient temperature change value is large, the ambient temperature change is obvious, that is, the correction parameter needs to be corrected, otherwise, the ambient temperature change value is small, the ambient temperature change is not obvious, and the correction parameter does not need to be corrected.
The correction module 150 is configured to control the calculation module to reacquire an image required for correction and recalculate the correction parameter to obtain the corrected correction parameter when the ambient temperature variation value is greater than or equal to the preset ambient temperature variation value, so as to avoid the situation that the correction parameter is inaccurate due to large ambient temperature variation and long service time, enhance the temperature adaptability of the CMOS image sensor, and facilitate improvement of accuracy and reliability of the correction parameter, thereby improving image quality.
The correction module 160 is configured to correct the CMOS image sensor according to the corrected correction parameter.
In an embodiment of the present invention, the calibration module 160 calibrates the CMOS image sensor according to the corrected calibration parameter, including:
y′i＝Ki×yi+bi
wherein i is any column in the CMOS image sensor, and yiTo-be-calibrated for CMOS image sensor acquisitionPositive image data, y'iFor corrected image data, KiTo correct the gain, biTo correct for the offset.
Specifically, the correction parameter K is obtained by the calculation method of the correction parameteriAnd biThen, when the CMOS image sensor newly acquires the image data, the original data y of each column of imageiFrom formula y'i＝Ki×yi+biCorrected image data y 'are obtained after correction'iCorrected image data y'iNamely, the column noise of the image can be basically eliminated, and the image quality is higher.
The method comprises the steps of acquiring environmental temperature data in real time after the equipment normally operates, judging whether the environmental temperature changes to a threshold value (namely a preset temperature change value) which needs to be corrected again, when the environmental temperature reaches the threshold value which needs to be corrected, correcting and storing the parameters again by the equipment, namely, acquiring an image which needs to be corrected again, recalculating a new correction parameter according to the image which needs to be corrected, storing the new correction parameter, and finally correcting the CMOS image sensor according to the new correction parameter, so that the condition that the correction parameter is inaccurate due to large environmental temperature change and long service time is avoided, the temperature adaptability of the CMOS image sensor is enhanced, the accuracy and the reliability of the correction parameter are improved, and the image quality is improved.
According to the correction system of the CMOS image sensor, provided by the embodiment of the invention, the correction parameters of the CMOS image sensor can be corrected according to the environment temperature change condition in the working process of equipment, so that the accuracy and the reliability of the correction parameters are improved, the temperature adaptability of the CMOS image sensor is improved, the correction result is accurate and reliable, the column noise is effectively eliminated, and the image quality is improved.
Further embodiments of the present invention also propose an image processing apparatus including a CMOS image sensor, and a correction system of the CMOS image sensor described in any of the above embodiments of the present invention. Therefore, a specific implementation manner of the image processing apparatus according to the embodiment of the present invention is similar to that of the calibration system of the CMOS image sensor according to the embodiment of the present invention, and please refer to the description of the system part specifically, and details are not repeated here in order to reduce redundancy.
According to the image processing equipment provided by the embodiment of the invention, the correction parameters of the CMOS image sensor can be corrected according to the change condition of the environmental temperature in the working process of the equipment, so that the accuracy and the reliability of the correction parameters are improved, the temperature adaptability of the CMOS image sensor is improved, the correction result is accurate and reliable, the column noise is effectively eliminated, and the image quality is improved.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (11)
1. A method for calibrating a CMOS image sensor, comprising the steps of:
after the CMOS image sensor is powered on, acquiring initial environment temperature;
acquiring an image required for correction, and calculating a correction parameter according to the image required for correction;
detecting the ambient temperature in real time, and obtaining an ambient temperature change value by combining the initial ambient temperature;
judging whether the environmental temperature change value is larger than or equal to a preset environmental temperature change value or not;
if so, acquiring the image required by correction again, and recalculating the correction parameters to obtain corrected correction parameters;
and correcting the CMOS image sensor according to the corrected correction parameters.
2. The method according to claim 1, wherein the images required for correction include a first image output from the CMOS image sensor with a luminance higher than a preset luminance and a second image output from the CMOS image sensor with a luminance lower than the preset luminance, and the calculating of the correction parameter based on the images required for correction includes:
calculating the average value of pixels of each column of the first image and the second image;
calculating the pixel average value of the first image and the second image;
and calculating the correction parameter according to the pixel average value of each column of the first image and the second image and the pixel average value of the first image and the second image.
3. The method according to claim 2, wherein the corrected correction parameters comprise a correction gain and a correction offset, and the correcting the CMOS image sensor according to the corrected correction parameters comprises:
y'i＝Ki×yi+bi
wherein i is any column in the CMOS image sensor, and yiImage data to be corrected, y ', acquired for a CMOS image sensor'iFor corrected image data, KiFor the correction gain, biIs the correction bias.
4. The method of claim 3, wherein the correction gain is calculated by:
where i is any column in the CMOS image sensor, and KiFor the purpose of the said correction gain, the gain is,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
5. The method of claim 4, wherein the correction bias is calculated by:
where i is any column in the CMOS image sensor, biIn order to correct the offset, the offset is corrected,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
6. A calibration system for a CMOS image sensor, comprising:
the acquisition module is used for acquiring the initial environment temperature after the CMOS image sensor is electrified;
the calculation module is used for acquiring an image required by correction and calculating a correction parameter according to the image required by correction;
the detection module is used for detecting the ambient temperature in real time and obtaining an ambient temperature change value by combining the initial ambient temperature;
the judging module is used for judging whether the environment temperature change value is larger than or equal to a preset environment temperature change value;
the correction module is used for controlling the calculation module to acquire an image required by correction again and calculating correction parameters again to obtain corrected correction parameters when the ambient temperature change value is larger than or equal to a preset ambient temperature change value;
and the correction module is used for correcting the CMOS image sensor according to the corrected correction parameters.
7. The CMOS image sensor correction system of claim 6, wherein the images required for correction include a first image output by the CMOS image sensor with a brightness higher than a preset brightness and a second image output by the CMOS image sensor with a brightness lower than the preset brightness, and the calculation module calculates correction parameters according to the images required for correction, including:
calculating the average value of pixels of each column of the first image and the second image;
calculating the pixel average value of the first image and the second image;
and calculating the correction parameter according to the pixel average value of each column of the first image and the second image and the pixel average value of the first image and the second image.
8. The CMOS image sensor calibration system of claim 7, wherein the modified calibration parameters comprise a calibration gain and a calibration offset, and the calibration module calibrates the CMOS image sensor according to the modified calibration parameters, comprising:
y'i＝Ki×yi+bi
wherein i is any column in the CMOS image sensor, and yiImage data to be corrected, y ', acquired for a CMOS image sensor'iFor corrected image data, KiFor the correction gain, biIs the correction bias.
9. The CMOS image sensor calibration system of claim 8,
the calculation mode of the correction gain is as follows:
where i is any column in the CMOS image sensor, and KiFor the purpose of the said correction gain, the gain is,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the image of the ith column of the second imageThe average value of the elements is calculated,
is the average value of the pixels of the second image.
10. The CMOS image sensor calibration system of claim 9,
the calculation method of the correction bias is as follows:
where i is any column in the CMOS image sensor, biIn order to correct the offset, the offset is corrected,
is the average value of the pixels of the ith column of the first image,
is the average value of the pixels of the first image,
is the average value of the pixels of the ith column of the second image,
is the average value of the pixels of the second image.
11. An image processing apparatus characterized by comprising:
a CMOS image sensor; and
a correction system for a CMOS image sensor as claimed in any one of claims 6 to 10.
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