CN108668124B - Photosensitive chip testing method and device based on charge calculation - Google Patents
Photosensitive chip testing method and device based on charge calculation Download PDFInfo
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- CN108668124B CN108668124B CN201710212284.4A CN201710212284A CN108668124B CN 108668124 B CN108668124 B CN 108668124B CN 201710212284 A CN201710212284 A CN 201710212284A CN 108668124 B CN108668124 B CN 108668124B
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Abstract
The invention provides a photosensitive chip testing method and equipment based on charge calculation, which can test the effect of a photosensitive chip through the performance-to-noise ratio (SNR) 10 test of the photosensitive chip, the full charge capacity test of the photosensitive chip, the photosensitive capability test of the photosensitive chip, the dynamic range test of the photosensitive chip and the dark noise test of the photosensitive chip, and can be matched with a reference for type selection, thereby enhancing the user experience.
Description
Technical Field
The invention relates to a photosensitive chip testing method based on charge calculation.
Background
The sensitization chip is as the most important part in the camera components and parts, and the quality of its quality has decided the quality of camera, if sensitization chip appears the inefficacy bad of any reason, can all bring serious consequence for whole camera system, and the effect of making a video recording of light person is poor, and the whole camera of heavy person all will scrap in batches, return goods, influences user experience.
The test to sensitization chip in the trade at present is based on the aassessment of camera module aspect, because the encapsulation restriction of sensitization chip, the module factory can't test the chip effect when the chip supplied materials. The test can be carried out only when the chip is made into a module sample, but the test is mostly limited to the module application layer surfaces such as analytic force, Shading (brightness uniformity), dirty points and the like. Due to the lack of complete evaluation tests for individual photosensitive chips, various problems often occur later in the project after the photosensitive chips have been incorporated into the camera module, and it is only now desired to overcome these problems. This results in a limited space for optimization.
In addition, when selecting the type of the photosensitive chip to be used in the camera module, it is necessary to clearly understand the advantages and disadvantages of the chip performance and combine the advantages and disadvantages performance effect with the cost performance.
At present, the evaluation test mode of the photosensitive chip in the industry cannot meet the industry requirement.
Disclosure of Invention
The invention aims to provide a photosensitive chip testing method based on charge calculation, which can solve the problem that the conventional scheme cannot accurately test a photosensitive chip.
In order to solve the above problems, the present invention provides a method for paging reading materials in Epub format, comprising: a photosensitive chip testing method based on charge calculation is characterized by comprising the following steps:
testing the performance-to-noise ratio of the photosensitive chip by 10;
testing the full charge capacity of the photosensitive chip;
testing the light sensitivity of the light sensitive chip;
testing the dynamic range of the photosensitive chip;
and testing dark noise of the photosensitive chip.
Further, in the above method, the signal-to-noise ratio 10 test includes:
shooting 18% of gray card images by using a camera module in different environment illumination, and extracting a signal value of 100x100 pixels in the center of the gray card images, wherein the camera module comprises a photosensitive chip;
sequentially carrying out white balance, color correction matrix and interpolation calculation on the signal values of 100x100 pixels in the center of the gray card image to obtain processed signal values;
and calculating a signal-to-noise ratio according to the processed signal values, drawing a curve of the signal-to-noise ratio and the different environment illumination, and taking the corresponding environment brightness value as a final signal-to-noise ratio 10 result when the signal-to-noise ratio is equal to 10.
Further, in the above method, the different ambient illuminance includes:
from dark to bright, the illumination is customized to be 17 lux-1024 lux.
Further, in the above method, the Color Correction Matrix (CCM) is obtained according to the following formula:
wherein, R ', G ', B ' are red, green and blue channel signal values of the CIE1937 standard color matching curve, R, G, B is red, green and blue channel signal values processed by white balance, respectively, a11 a12.
Further, in the above method, the signal-to-noise ratio is calculated according to the following formula:
SNR＝Singal/noise，
the SNR is the SNR, single is a processed signal value Y obtained by sequentially performing the White Balance (WB), the color correction matrix and the interpolation calculation, and noise is Std deviation (Y) which is a standard deviation.
Further, in the above method, the full charge capacity test comprises:
fixing the brightness of a light source, and adjusting the exposure time to enable signal values of four channels of R, Gr, Gb and B of an image picture shot by a camera module to be full;
continuously shooting two pictures 1 by the camera module under each step exposed for 1ms, and calculating a noise value under each step according to the continuously shot two pictures under each step exposed for 1 ms;
and describing a group of linear curves by the signal value and the noise value of each picture under each step, taking the maximum signal value and the noise value in the linear curves, and calculating the full charge capacity according to the maximum signal value and the noise value.
Further, in the above method, the noise value δ at each of the steps is calculated according to the following formula2：
Wherein f is1And f2Respectively representing the signal values of two pictures continuously shot under the steps of 1ms of exposure, n representing the number of pixels in the pictures obtained by subtracting the signal values of the two pictures continuously shot under the steps of 1ms of exposure, xiRepresenting the i-th pixel value of the n pixels of the picture by subtracting said signal values,
representing the average value of each pixel in the picture by subtracting the signal values.
Further, in the above method, the photosensitivity test comprises:
fixing the brightness of a light source, and adjusting the exposure time to enable signal values of four channels of R, Gr, Gb and B of an image picture shot by a camera module to be full;
continuously shooting two pictures by the camera module under each step of 1ms of exposure;
drawing curves of signal values and exposure time of four channels R, Gr, Gb and B of each picture;
and converting the exposure time in the curve of the signal value and the exposure time into efficiency of the environmental illumination and the time, generating a curve of the signal value and the efficiency of the environmental illumination and the time, and taking a signal value corresponding to the time when the efficiency of the environmental illumination and the time is equal to 1 in the curve of the signal value and the efficiency of the environmental illumination and the time as a final result.
Further, in the above method, the exposure time in the curve of the signal value and the exposure time is converted into efficiency with the ambient illuminance and time by the following formula:
wherein E isp(lux, sec) is the efficiency with ambient illumination and time, m is the magnification factor, the values in this equation are 0, E0 is the ambient illumination value, e.g., 3000K, R0 is the physical reflectance, TL is the exposure time, F is the lens aperture value, lux is lux, the units of ambient illumination, sec is seconds.
Further, in the above method, the dynamic range test comprises:
the camera module shoots a picture in a dark environment;
and calculating the dynamic range of the photosensitive chip according to the picture in the dark environment.
Further, in the above method, the dynamic range of the photosensitive chip is calculated by the following formula:
wherein FSD (full Scale deflection) is the maximum signal value of the photosensitive chip, n is the number of pixels in a single picture under the condition of full darkness, xiRepresenting the ith pixel value of n pixels in a single picture in said captured all-dark environment,
represents the average value of each pixel in a single picture in the captured all-dark environment.
Further, in the above method, the Dark noise (Dark noise) test includes:
the camera module shoots 100 pictures under the two conditions of maximum and minimum full-dark state analog gain;
and calculating the random noise value, the fixed longitudinal stripe noise value and the fixed transverse stripe noise value of each picture.
Further, in the above method, a Random Noise value (Random Noise) is calculated by the following formula:
wherein TemporalNoise (dB) is a random noise value, M is the number of horizontal pixel coordinates of each picture, N is the number of vertical pixel coordinates of each picture,
the noise of the pixel when the horizontal pixel coordinate is i and the vertical pixel coordinate is j, and the FSD is the maximum signal value of the photosensitive chip.
Further, in the above method, the fixed horizontal streak noise value is calculated by the following formula:
wherein HFPNLevelFor the fixed vertical stripe noise value, FSD (full Scale deflection) is the maximum signal value of the photosensitive chip, N is the number of horizontal pixel coordinates of each picture, RjIs the pixel value with the horizontal pixel coordinate j.
Further, in the above method, a Fixed Vertical streak Noise Value (VFPN) is calculated by the following formula:
wherein, VFPNLevelFor the fixed vertical stripe noise value, FSD (full Scale deflection) is the maximum signal value of the photosensitive chip, M is the number of vertical pixel coordinates of each picture, RiIs the pixel value with vertical pixel coordinate i.
According to another aspect of the present invention, there is provided a charge calculation-based photosensitive chip test apparatus, including:
the device comprises a signal to noise ratio 10 testing module, a signal to noise ratio detection module and a signal processing module, wherein the signal to noise ratio 10 testing module is used for testing the signal to noise ratio 10 of a photosensitive chip;
the full charge capacity testing module is used for testing the full charge capacity of the photosensitive chip;
the photosensitive capability test module is used for testing the photosensitive capability of the photosensitive chip;
the dynamic range testing module is used for testing the dynamic range of the photosensitive chip;
and the dark noise test module is used for testing the dark noise of the photosensitive chip.
Further, in the above device, the signal to noise ratio 10 testing module is configured to shoot an 18% gray card image by using a camera module in different environmental illuminances, and extract a signal value of 100 × 100 pixels in the center of the gray card image, where the camera module includes a photosensitive chip; sequentially carrying out white balance, color correction matrix and interpolation calculation on the signal values of 100x100 pixels in the center of the gray card image to obtain processed signal values; and calculating a signal-to-noise ratio according to the processed signal values, drawing a curve of the signal-to-noise ratio and the different environment illumination, and taking the corresponding environment brightness value as a final signal-to-noise ratio 10 result when the signal-to-noise ratio is equal to 10.
Further, in the above device, the full charge capacity testing module is configured to fix brightness of the light source, and adjust exposure time to make signal values of four channels R, Gr, Gb, and B of an image captured by the image capturing module full; continuously shooting two pictures 1 by the camera module under each step exposed for 1ms, and calculating a noise value under each step according to the continuously shot two pictures under each step exposed for 1 ms; and describing a group of linear curves by the signal value and the noise value of each picture under each step, taking the maximum signal value and the noise value in the linear curves, and calculating the full charge capacity according to the maximum signal value and the noise value.
Further, in the above device, the photosensitive capability testing module is configured to fix brightness of the light source, and adjust exposure time to make signal values of four channels R, Gr, Gb, and B of an image frame captured by the camera module be full; continuously shooting two pictures by the camera module under each step of 1ms of exposure; drawing curves of signal values and exposure time of four channels R, Gr, Gb and B of each picture; converting the exposure time in the curve of the signal value and the exposure time into the efficiency of the environmental illumination and the time, generating the curve of the signal value and the efficiency of the environmental illumination and the time, and taking the signal value corresponding to the time when the efficiency of the environmental illumination and the time is equal to 1 in the curve of the signal value and the efficiency of the environmental illumination and the time as a final result
Further, in the above device, the dynamic range testing module is configured to take a picture of the image pickup module in a dark environment; and calculating the dynamic range of the photosensitive chip according to the picture in the dark environment.
Further, in the above device, the dark noise test module is configured to take 100 pictures of the full dark state under two conditions, namely maximum and minimum analog gains; and calculating the random noise value, the fixed longitudinal stripe noise value and the fixed transverse stripe noise value of each picture.
The present application also provides one or more machine-readable media having instructions stored thereon, which when executed by one or more processors, cause a terminal device to perform any of the methods described above.
Compared with the prior art, the method and the device can reach the effect of the photosensitive chip through the performance-to-noise ratio (SNR) 10 test of the photosensitive chip, the full charge capacity test of the photosensitive chip, the photosensitive capability test of the photosensitive chip, the dynamic range test of the photosensitive chip and the dark noise test of the photosensitive chip, are used for type selection and matching reference, and enhance the user experience.
Drawings
FIG. 1 is a graph of a signal to noise ratio 10 test according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a camera module according to an embodiment of the present invention continuously taking two pictures at each step of 1ms exposure;
FIG. 3 is a graph of signal values and noise values for one embodiment of the present invention;
FIG. 4 is a graph of signal values and exposure time for one embodiment of the present invention;
FIG. 5 is a graph of signal values and efficiency with ambient illumination and time for an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1, the present invention provides a photosensitive chip testing method based on charge calculation, including a Signal Noise Ratio (Signal Noise Ratio)10 test of a photosensitive chip, where the Signal Noise Ratio 10 test includes:
in different environment illumination, shooting 18% gray card (Grey Chart) images by using a camera module, and extracting a signal value of 100x100 pixels (pixels) in the center of each gray card image, wherein the camera module comprises a photosensitive chip;
sequentially carrying out White Balance (WB), Color Correction Matrix (CCM) and interpolation calculation on the signal values of 100x100 pixels in the center of the gray card image to obtain processed signal values;
and calculating a signal-to-noise ratio (SNR) according to the processed signal values, drawing a curve of the SNR and the different environmental illumination, and taking the corresponding environmental brightness value as a final SNR10 (SNR10) result when the SNR is equal to 10.
In an embodiment of the method for testing a light sensing chip based on charge calculation, the different environmental illuminances include:
from dark to bright, the illumination is customized to be 17 lux-1024 lux.
In an embodiment of the photosensitive chip testing method based on charge calculation of the present invention, the Color Correction Matrix (CCM) is obtained according to the following formula:
wherein, R ', G ', B ' are red, green and blue channel signal values of the CIE1937 standard color matching curve, R, G, B is a red, green and blue channel signal value after white balance processing, respectively, a11 a12.
In an embodiment of the method for testing a photosensitive chip based on charge calculation of the present invention, the signal-to-noise ratio (SNR) is calculated according to the following formula:
SNR＝Singal/noise，
the SNR is the SNR, single is a processed signal value Y obtained by sequentially performing White Balance (WB), Color Correction Matrix (CCM) and interpolation calculation, noise is Std (Y), and Std is a standard deviation. For example, the processed signal value Y in NTSC gamut space is as follows:
NTSC
Y＝0.2989 R+0.5870 G+0.1140 B。
the photosensitive chip testing method based on charge calculation further comprises a Full charge Capacity (Full Well Capacity) test of the photosensitive chip, wherein the Full charge Capacity (Full Well Capacity, FWC) test comprises the following steps:
fixing the brightness of a light source, and adjusting the exposure time to enable signal values of four channels of R, Gr, Gb and B of an image picture shot by a camera module to be full;
as shown in fig. 2, the camera module continuously takes two pictures 1 at each step of 1ms of exposure, and calculates a noise value (Var) at each step according to the two pictures continuously taken at each step of 1ms of exposure;
as shown in fig. 3, a set of linear curves is drawn for the signal value and the noise value of each picture at each step, the maximum signal value and the noise value in the linear curves are taken, and the full charge capacity is calculated according to the maximum signal value and the noise value. Specifically, FWC is the full charge capacity of the photo-sensing chip, simply the ability of the photo-sensing chip to receive the maximum charge. If the value is larger, the capacity of the photosensitive chip for receiving photons and collecting electrons is stronger, and the problems of overflow and the like are not easy to cause.
In an embodiment of the photosensitive chip testing method based on charge calculation, the noise value delta under each step is calculated according to the following formula2：
Wherein f is1And f2Respectively representing the signal values of two pictures continuously shot under the steps of 1ms of exposure, n representing the number of pixels in the pictures obtained by subtracting the signal values of the two pictures continuously shot under the steps of 1ms of exposure, xiRepresenting the i-th pixel value of the n pixels of the picture by subtracting said signal values,
representing the average value of each pixel in the picture by subtracting the signal values.
The photosensitive chip testing method based on charge calculation further comprises a photosensitive capability (Sensitivity) test of the photosensitive chip, wherein the photosensitive capability test comprises the following steps:
fixing the brightness of a light source, and adjusting the exposure time to enable signal values of four channels of R, Gr, Gb and B of an image picture shot by a camera module to be full;
as shown in fig. 2, the camera module takes two pictures 1 in succession at each step of 1ms exposure;
as shown in fig. 4, plotting the signal values and exposure time of the four channels R, Gr, Gb, B of each picture;
as shown in fig. 5, the Exposure time in the curve of the signal value and the Exposure time is converted into the efficiency with respect to the ambient illuminance and time, a curve of the signal value and the efficiency with respect to the ambient illuminance and time is generated, and the signal value corresponding to the case where the efficiency with respect to the ambient illuminance and time (Face Plate Exposure) is equal to 1 in the curve of the signal value and the efficiency with respect to the ambient illuminance and time is taken as the final result.
In an embodiment of the method for testing a photosensitive chip based on charge calculation, the exposure time in the curve of the signal value and the exposure time is converted into the efficiency of the ambient illumination and the time by the following formula:
wherein E isp(lux, sec) is the efficiency with ambient illumination and time, m is the magnification factor, the values in this equation are 0, E0 is the ambient illumination value, e.g., 3000K, R0 is the physical reflectance, TL is the exposure time, F is the lens aperture value, lux is lux, the unit of ambient illumination, sec is seconds (Second).
The photosensitive chip testing method based on charge calculation further comprises a Dynamic Range test of the photosensitive chip, wherein the Dynamic Range test comprises the following steps:
the camera module shoots a picture in a dark environment;
and calculating the dynamic range of the photosensitive chip according to the picture in the dark environment. Here, the dynamic range of the photo sensor chip refers to a signal range between a maximum signal value and a minimum signal value of the photo sensor chip. The larger the signal range, the more detail an image can represent. For example, in a scene where a bright-dark boundary is photographed, if the Dynamic Range value is large, both bright and dark details can be well presented. If the Dynamic Range is too small, either the bright place details are clear, but the dark place details are too dark to be presented. Or the details are clear in the dark, but the bright areas are already over-exposed and cannot be presented.
In an embodiment of the method for testing the photosensitive chip based on charge calculation, the dynamic range of the photosensitive chip is calculated by the following formula:
wherein FSD (full Scale deflection) is the maximum signal value of the photosensitive chip, n is the number of pixels in a single picture under the condition of full darkness, xiRepresenting the ith pixel value of n pixels in a single picture in said captured all-dark environment,
represents the average value of each pixel in a single picture in the captured all-dark environment.
The photosensitive chip testing method based on charge calculation further comprises a Dark noise test of the photosensitive chip, wherein the Dark noise (Dark noise) test comprises the following steps:
the camera module shoots 100 pictures under the conditions of maximum and minimum full-dark state analog gain (Again is min/max);
the Random Noise value (Random Noise) and the Fixed Vertical stripe Noise Value (VFPN) and the Fixed Horizontal stripe Noise value (HFPN) of each picture were calculated. Here, the Dark Noise includes three terms of a Random Noise value (Random Noise) and a Fixed Vertical streak Noise Value (VFPN) and a Fixed Horizontal streak Noise value (HFPN).
In an embodiment of the method for testing a photosensitive chip based on charge calculation of the present invention, a Random Noise value (Random Noise) is calculated by the following formula:
wherein TemporalNoise (dB) is a random noise value, M is the number of horizontal pixel coordinates of each picture, N is the number of vertical pixel coordinates of each picture,
the horizontal pixel coordinate is i, and the vertical pixel coordinate is j, and the fsd (full Scale deflection) is the maximum signal value of the sensor chip.
In an embodiment of the method for testing a photosensitive chip based on charge calculation, a Fixed Horizontal stripe Noise value (HFPN) is calculated by the following formula:
wherein HFPNLevelFor the fixed vertical stripe noise value, FSD (full Scale deflection) is the maximum signal value of the photosensitive chip, N is the number of horizontal pixel coordinates of each picture, RjIs the pixel value with the horizontal pixel coordinate j.
In an embodiment of the photosensitive chip testing method based on charge calculation, a Fixed Vertical stripe Noise Value (VFPN) is calculated by the following formula:
wherein, VFPNLevelFor the fixed vertical stripe noise value, FSD (full Scale deflection) is the maximum signal value of the photosensitive chip, M is the number of vertical pixel coordinates of each picture, RiIs the pixel value with vertical pixel coordinate i.
According to another aspect of the present invention, there is provided a charge calculation-based photosensitive chip test apparatus, including:
the device comprises a signal to noise ratio 10 testing module, a signal to noise ratio detection module and a signal processing module, wherein the signal to noise ratio 10 testing module is used for testing the signal to noise ratio 10 of a photosensitive chip;
the full charge capacity testing module is used for testing the full charge capacity of the photosensitive chip;
the photosensitive capability test module is used for testing the photosensitive capability of the photosensitive chip;
the dynamic range testing module is used for testing the dynamic range of the photosensitive chip;
and the dark noise test module is used for testing the dark noise of the photosensitive chip.
Further, in the above device, the signal to noise ratio 10 testing module is configured to shoot an 18% gray card image by using a camera module in different environmental illuminances, and extract a signal value of 100 × 100 pixels in the center of the gray card image, where the camera module includes a photosensitive chip; sequentially carrying out white balance, color correction matrix and interpolation calculation on the signal values of 100x100 pixels in the center of the gray card image to obtain processed signal values; and calculating a signal-to-noise ratio according to the processed signal values, drawing a curve of the signal-to-noise ratio and the different environment illumination, and taking the corresponding environment brightness value as a final signal-to-noise ratio 10 result when the signal-to-noise ratio is equal to 10.
Further, in the above device, the full charge capacity testing module is configured to fix brightness of the light source, and adjust exposure time to make signal values of four channels R, Gr, Gb, and B of an image captured by the image capturing module full; continuously shooting two pictures 1 by the camera module under each step exposed for 1ms, and calculating a noise value under each step according to the continuously shot two pictures under each step exposed for 1 ms; and describing a group of linear curves by the signal value and the noise value of each picture under each step, taking the maximum signal value and the noise value in the linear curves, and calculating the full charge capacity according to the maximum signal value and the noise value.
Further, in the above device, the photosensitive capability testing module is configured to fix brightness of the light source, and adjust exposure time to make signal values of four channels R, Gr, Gb, and B of an image frame captured by the camera module be full; continuously shooting two pictures by the camera module under each step of 1ms of exposure; drawing curves of signal values and exposure time of four channels R, Gr, Gb and B of each picture; converting the exposure time in the curve of the signal value and the exposure time into the efficiency of the environmental illumination and the time, generating the curve of the signal value and the efficiency of the environmental illumination and the time, and taking the signal value corresponding to the time when the efficiency of the environmental illumination and the time is equal to 1 in the curve of the signal value and the efficiency of the environmental illumination and the time as a final result
Further, in the above device, the dynamic range testing module is configured to take a picture of the image pickup module in a dark environment; and calculating the dynamic range of the photosensitive chip according to the picture in the dark environment.
Further, in the above device, the dark noise test module is configured to take 100 pictures of the full dark state under two conditions, namely maximum and minimum analog gains; and calculating the random noise value, the fixed longitudinal stripe noise value and the fixed transverse stripe noise value of each picture.
The present application also provides one or more machine-readable media having instructions stored thereon, which when executed by one or more processors, cause a terminal device to perform any of the methods described above.
In summary, the invention can find the effect of the photosensitive chip through the performance-to-noise ratio 10 test of the photosensitive chip, the full charge capacity test of the photosensitive chip, the photosensitive capability test of the photosensitive chip, the dynamic range test of the photosensitive chip and the dark noise test of the photosensitive chip, so as to be matched with a model for reference and enhance the user experience.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (18)
1. A photosensitive chip testing method based on charge calculation is characterized by comprising the following steps:
testing the signal-to-noise ratio 10 of the photosensitive chip;
testing the full charge capacity of the photosensitive chip;
testing the light sensitivity of the light sensitive chip;
testing the dynamic range of the photosensitive chip;
testing the dark noise of the photosensitive chip;
wherein the signal-to-noise ratio 10 test comprises:
shooting 18% of gray card images by using a camera module in different environment illumination, and extracting a signal value of 100x100 pixels in the center of the gray card images, wherein the camera module comprises a photosensitive chip;
sequentially carrying out white balance, color correction matrix and interpolation calculation on the signal values of 100x100 pixels in the center of the gray card image to obtain processed signal values;
calculating a signal-to-noise ratio according to the processed signal value, drawing a curve of the signal-to-noise ratio and the different environmental illumination, and taking a corresponding environmental brightness value as a final signal-to-noise ratio 10 result when the signal-to-noise ratio is equal to 10;
obtaining the color correction matrix according to the following formula:
wherein, R ', G ', B ' are red, green and blue channel signal values of the CIE1937 standard color matching curve, R, G, B is red, green and blue channel signal values processed by white balance, respectively, a11 a12.
2. The method of claim 1, wherein the different ambient illumination comprises:
from dark to bright, the illumination is customized to be 17 lux-1024 lux.
3. The charge calculation-based photosensing chip testing method according to claim 1, wherein said signal-to-noise ratio is calculated according to the formula:
SNR＝Singal/noise，
the SNR is the signal-to-noise ratio, single is a processed signal value Y obtained through the white balance, the color correction matrix and the interpolation calculation in sequence, noise is Std (Y), and Std is a standard deviation.
4. The charge calculation-based photosensitive chip testing method of claim 1, wherein the full charge capacity test comprises:
fixing the brightness of a light source, and adjusting the exposure time to enable signal values of four channels of R, Gr, Gb and B of an image picture shot by a camera module to be full;
continuously shooting two pictures by the camera module under each step exposed for 1ms, and calculating a noise value under each step according to the continuously shot two pictures under each step exposed for 1 ms;
and describing a group of linear curves by the signal value and the noise value of each picture under each step, taking the maximum signal value and the noise value in the linear curves, and calculating the full charge capacity according to the maximum signal value and the noise value.
5. The method for testing photosensitive chips based on charge calculation of claim 4, wherein the noise value δ at each of said steps is calculated according to the following formula2：
Wherein f is1And f2Respectively representing the signal values of two pictures continuously shot under the steps of 1ms of exposure, n representing the number of pixels in the pictures obtained by subtracting the signal values of the two pictures continuously shot under the steps of 1ms of exposure, xiRepresenting the i-th pixel value of the n pixels of the picture by subtracting said signal values,
representing the average value of each pixel in the picture by subtracting the signal values.
6. The method for testing a photosensitive chip based on charge calculation according to claim 1, wherein the photosensitive capability test comprises:
fixing the brightness of a light source, and adjusting the exposure time to enable signal values of four channels of R, Gr, Gb and B of an image picture shot by a camera module to be full;
continuously shooting two pictures by the camera module under each step of 1ms of exposure;
drawing curves of signal values and exposure time of four channels R, Gr, Gb and B of each picture;
and converting the exposure time in the curve of the signal value and the exposure time into efficiency of the environmental illumination and the time, generating a curve of the signal value and the efficiency of the environmental illumination and the time, and taking a signal value corresponding to the time when the efficiency of the environmental illumination and the time is equal to 1 in the curve of the signal value and the efficiency of the environmental illumination and the time as a final result.
7. The charge calculation-based photosensitive chip testing method according to claim 6, wherein the exposure time in the curve of the signal value and the exposure time is converted into efficiency with the ambient illuminance and time by the following formula:
wherein E isp(lux, sec) is the efficiency with ambient illumination and time, m is the amplification factor, the value in this equation is 0, E0Is an ambient illuminance value, R0Is the physical reflectance, TLFor exposure time, F is the lens aperture, lux is lux, ambient illuminance units, and sec is seconds.
8. The charge calculation-based photosensitive chip testing method according to claim 1, wherein the dynamic range test comprises:
the camera module shoots a picture in a dark environment;
and calculating the dynamic range of the photosensitive chip according to the picture in the dark environment.
9. The method of claim 8, wherein the dynamic range of the light sensing chip is calculated by the following formula:
wherein FSD is the maximum signal value of the photosensitive chip, n is the number of pixels in a single picture under the condition of full-dark shooting, and xiRepresenting the ith pixel value of n pixels in a single picture in said captured all-dark environment,
represents the average value of each pixel in a single picture in the photographic all-dark environment.
10. The charge calculation-based photosensitive chip testing method of claim 1, wherein the dark noise test comprises:
the camera module shoots 100 pictures under the two conditions of maximum and minimum full-dark state analog gain;
and calculating the random noise value, the fixed longitudinal stripe noise value and the fixed transverse stripe noise value of each picture.
11. The charge calculation-based photosensitive chip testing method according to claim 10, wherein the random noise value is calculated by the following formula:
wherein TemporalNoise (dB) is a random noise value, M is the number of horizontal pixel coordinates of each picture, N is the number of vertical pixel coordinates of each picture,
the noise of the pixel when the horizontal pixel coordinate is i and the vertical pixel coordinate is j, and the FSD is the maximum signal value of the photosensitive chip.
12. The charge calculation-based photosensitive chip test method according to claim 10, wherein the fixed horizontal streak noise value is calculated by the following formula:
wherein HFPNLevelFor fixed longitudinal stripe noise value, FSD is the maximum signal value of the photosensitive chip, N is the number of horizontal pixel coordinates of each picture, RjIs the pixel value with the horizontal pixel coordinate j.
13. The method for testing a photosensitive chip based on charge calculation of claim 10, wherein the fixed vertical stripe noise value is calculated by the following formula:
wherein, VFPNLevelFor fixed longitudinal stripe noise value, FSD is the maximum signal value of the photosensitive chip, M is the number of longitudinal pixel coordinates of each picture, RiIs the pixel value with vertical pixel coordinate i.
14. A light-sensing chip test apparatus based on charge calculation, comprising:
the signal-to-noise ratio 10 testing module is used for testing the signal-to-noise ratio 10 of the photosensitive chip;
the full charge capacity testing module is used for testing the full charge capacity of the photosensitive chip;
the photosensitive capability test module is used for testing the photosensitive capability of the photosensitive chip;
the dynamic range testing module is used for testing the dynamic range of the photosensitive chip;
the dark noise test module is used for testing the dark noise of the photosensitive chip;
wherein the signal-to-noise ratio 10 test comprises:
shooting 18% of gray card images by using a camera module in different environment illumination, and extracting a signal value of 100x100 pixels in the center of the gray card images, wherein the camera module comprises a photosensitive chip;
sequentially carrying out white balance, color correction matrix and interpolation calculation on the signal values of 100x100 pixels in the center of the gray card image to obtain processed signal values;
calculating a signal-to-noise ratio according to the processed signal value, drawing a curve of the signal-to-noise ratio and the different environmental illumination, and taking a corresponding environmental brightness value as a final signal-to-noise ratio 10 result when the signal-to-noise ratio is equal to 10;
obtaining the color correction matrix according to the following formula:
wherein, R ', G ', B ' are red, green and blue channel signal values of the CIE1937 standard color matching curve, R, G, B is red, green and blue channel signal values processed by white balance, respectively, a11 a12.
15. The photosensitive chip testing apparatus based on charge calculation of claim 14, wherein the full charge capacity testing module is configured to fix the brightness of the light source, and adjust the exposure time to make the signal values of the four channels R, Gr, Gb, and B captured by the camera module full; continuously shooting two pictures by the camera module under each step exposed for 1ms, and calculating a noise value under each step according to the continuously shot two pictures under each step exposed for 1 ms; and describing a group of linear curves by the signal value and the noise value of each picture under each step, taking the maximum signal value and the noise value in the linear curves, and calculating the full charge capacity according to the maximum signal value and the noise value.
16. The photosensitive chip testing apparatus based on charge calculation of claim 14, wherein the photosensitive capability testing module is configured to fix a brightness of the light source, and adjust an exposure time to make signal values of four channels R, Gr, Gb, and B of an image captured by the image capturing module be full; continuously shooting two pictures by the camera module under each step of 1ms of exposure; drawing curves of signal values and exposure time of four channels R, Gr, Gb and B of each picture; and converting the exposure time in the curve of the signal value and the exposure time into efficiency of the environmental illumination and the time, generating a curve of the signal value and the efficiency of the environmental illumination and the time, and taking a signal value corresponding to the time when the efficiency of the environmental illumination and the time is equal to 1 in the curve of the signal value and the efficiency of the environmental illumination and the time as a final result.
17. The photosensitive chip test equipment based on charge calculation as claimed in claim 14, wherein the dynamic range test module is used for the camera module to take pictures in a dark environment; and calculating the dynamic range of the photosensitive chip according to the picture in the dark environment.
18. The charge calculation-based photosensitive chip test apparatus according to claim 14, wherein the dark noise test module is configured to take 100 pictures of the full-dark state with the maximum analog gain and the minimum analog gain; and calculating the random noise value, the fixed longitudinal stripe noise value and the fixed transverse stripe noise value of each picture.
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