CN107395921B - Difference detection method and device - Google Patents

The invention discloses a difference detection method and device. The method comprises the following steps: fixing an AD register parameter and a constant current source current parameter, and acquiring image data by adopting any CIS image sensor and acquiring a first pixel mean value of the currently acquired image data when the constant current source exposure duration parameter is adjusted to be a first exposure duration parameter; when the constant current source exposure duration parameter is adjusted to be a second exposure duration parameter, acquiring image data and obtaining a second pixel mean value of the currently acquired image data; acquiring an image data slope value corresponding to the CIS image sensor according to the first exposure duration parameter, the first pixel mean value, the second exposure duration parameter and the second pixel mean value; according to the image data slope value corresponding to the CIS image sensor and the image data slope value corresponding to the preset reference CIS image sensor, the difference rate between the CIS image sensor and the preset reference CIS image sensor is obtained, the time for adjusting parameters before image acquisition is shortened, and the accuracy of subsequent image acquisition is improved.

Difference detection method and device

Technical Field

The embodiment of the invention relates to the field of quality control, in particular to a difference detection method and device.

Background

An image sensor, also called a photosensitive element, is a device that converts an optical image into an electronic signal, and is widely used in various electro-optical devices. Currently, Image sensors are mainly classified into Charge Coupled Devices (CCDs) and Contact Image Sensors (CIS). The CIS image sensor has the advantages of good light source brightness, small distortion degree, small power consumption, small volume, light weight, low failure rate, good shock resistance, low requirement on use environment and the like, so that the CIS image sensor is widely applied.

However, the CIS image sensors vary greatly from batch to batch due to environmental and process factors during the production process. In the prior art, an enterprise using a CIS image sensor can represent the difference between CIS in a very poor way by acquiring white paper image data and calculating the image data in the process of flow control.

However, characterization in a range mode can only eliminate CIS image sensors that do not meet a preset range threshold. When dimension data is generated subsequently, differences between CIS image sensors in different batches are not quantified, so that parameter values of the CIS image sensors still need to be adjusted repeatedly before the CIS image sensors are used, and a large amount of time is wasted. Meanwhile, due to the inherent difference of the CIS image sensor, dimension data acquired each time are different, and the accuracy of subsequent image acquisition is influenced.

Disclosure of Invention

The invention provides a difference detection method and device, which are used for quantifying the difference rate of CIS image sensors in different batches.

In a first aspect, an embodiment of the present invention provides a difference detection method, where the method includes:

acquiring image data through any CIS image sensor according to a preset AD register parameter, a preset constant current source current parameter and a first exposure duration parameter, and acquiring a first pixel mean value of the currently acquired image data;

acquiring image data through any CIS image sensor according to the preset AD register parameter, the preset constant current source current parameter and a second exposure duration parameter, and acquiring a second pixel mean value of the currently acquired image data;

acquiring an image data slope value corresponding to any CIS image sensor according to the first exposure duration parameter, the first pixel mean value, the second exposure duration parameter and the second pixel mean value;

and acquiring the difference rate between any one CIS image sensor and a preset reference CIS image sensor according to the image data slope value corresponding to the CIS image sensor and the image data slope value corresponding to the preset reference CIS image sensor.

In a second aspect, an embodiment of the present invention further provides a difference detecting apparatus, where the apparatus includes:

the device comprises a first pixel mean value acquisition module, a second pixel mean value acquisition module and a third pixel mean value acquisition module, wherein the first pixel mean value acquisition module is used for acquiring image data through any CIS (contact image sensor) according to a preset AD register parameter, a preset constant current source current parameter and a first exposure duration parameter which are set by any CIS image sensor, and acquiring a first pixel mean value of the currently acquired image data;

the second pixel mean value acquisition module is used for acquiring image data according to the preset AD register parameter, the preset constant current source current parameter and the second exposure duration parameter through any one CIS image sensor and acquiring a second pixel mean value of the currently acquired image data;

an image data slope value obtaining module, configured to obtain an image data slope value corresponding to the CIS image sensor according to the first exposure duration parameter, the first pixel mean value, the second exposure duration parameter, and the second pixel mean value;

and the difference rate acquisition module is used for acquiring the difference rate between any one CIS image sensor and a preset reference CIS image sensor according to the image data slope rate value corresponding to the CIS image sensor and the image data slope rate value corresponding to the preset reference CIS image sensor.

According to the embodiment of the invention, by fixing the AD register parameter and the constant current source current parameter, when the constant current source exposure duration parameter is adjusted to be the first exposure duration parameter, any CIS image sensor is adopted to acquire image data and obtain the first pixel average value of the currently acquired image data; acquiring image data by adopting the CIS image sensor and acquiring a second pixel mean value of the currently acquired image data by adjusting the constant current source exposure duration parameter as a second exposure duration parameter; acquiring an image data slope value corresponding to the CIS image sensor according to the first exposure duration parameter, the first pixel mean value, the second exposure duration parameter and the second pixel mean value; the method has the advantages that the difference rate between the CIS image sensor and the preset reference CIS image sensor is obtained according to the image data slope value corresponding to the CIS image sensor and the image data slope value corresponding to the preset reference CIS image sensor, the problems that the differences of the CIS image sensors in different batches are not quantified, the parameters of an AD chip and a constant current source chip need to be adjusted repeatedly before the CIS image sensors are used for collecting images, a large amount of time is wasted, the subsequent image collecting precision is influenced are solved, the parameter adjusting time is shortened, and the subsequent image collecting precision is improved.

Drawings

Fig. 1 is a schematic flow chart of a difference detection method according to a first embodiment of the present invention.

Fig. 2 is a schematic flow chart of a difference detection method according to a second embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a difference detection apparatus according to a third embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

Example one

Fig. 1 is a schematic flow chart of a difference detection method according to an embodiment of the present invention, where the embodiment is applicable to a situation of difference detection of a CIS image sensor, and the method can be executed by a difference detection device, where the difference detection device can be implemented by software and/or hardware, and specifically includes the following steps:

step 110, acquiring image data through any CIS image sensor according to a preset AD register parameter, a preset constant current source current parameter and a first exposure duration parameter, and acquiring a first pixel mean value of the currently acquired image data;

when a CIS image sensor is used for image acquisition, an AD chip is required to complete sampling and analog-to-digital conversion, and a constant current source chip is required to provide current and exposure time for the CIS image sensor. The AD chip comprises two registers of gain and offset. Therefore, the AD gain parameter and the AD bias parameter are referred to as AD register parameters.

In the step, the AD register parameter is set as a preset AD register parameter, the constant current source current parameter is set as a preset constant current source current parameter, and the constant current source exposure duration parameter is set as a first exposure duration parameter. Under the parameter conditions, the image of the reference medium is acquired through any CIS image sensor to acquire corresponding image data. Wherein the reference medium may be white paper. The acquired image data may be gray scale data or RGB image data. Calculating the sum of pixel values of all pixel points in the obtained gray level image data according to the obtained image data, dividing the sum by the number of the pixel points to obtain an image data mean value, and recording the image data mean value as a first pixel mean value; or after summing the pixel values of the pixels corresponding to the RGB image data, dividing by 3 to obtain mixed image data, calculating the sum of the pixel values of all the pixels of the obtained mixed image data, dividing by the number of the pixels to obtain an image data mean value, and recording the image data mean value as a first pixel mean value.

The preset AD register parameters comprise a preset AD gain parameter and a preset AD offset parameter. The specific value of the preset AD gain parameter is not limited at all, and can be set as a conventional AD gain value, or can be adjusted correspondingly according to the brightness requirement of the acquired image; the specific numerical value of the preset AD offset parameter is not limited at all, and the numerical value can be adjusted correspondingly according to the actual acquisition requirement; the current parameters of the preset constant current source are not limited at all, and can be adjusted correspondingly according to the brightness of the collected image. Preferably, the AD offset parameter is preset to be neither forward nor reverse biased. Preferably, the preset constant current source current parameter is 30% to 80% of the maximum current parameter of the constant current source. Preferably, the constant current source current parameter is preset to be 50% of the constant current source current parameter.

Step 120, acquiring image data through any CIS image sensor according to the preset AD register parameter, the preset constant current source current parameter and the second exposure duration parameter, and acquiring a second pixel mean value of the currently acquired image data;

in this step, the fixed AD register parameter remains unchanged based on step 110, that is, the AD gain parameter is set as the preset AD gain parameter in step 110, and the AD offset parameter is set as the preset AD offset parameter in step 110. The fixed constant current source current parameter remains unchanged based on step 110, that is, the constant current source current parameter is set as the preset constant current source current parameter in step 110. And adjusting the constant current source exposure duration parameter to be a second exposure duration parameter. Under the above parameter conditions, image data of the same reference medium as that in step 110 is acquired by the CIS image sensor, and a corresponding image data mean value is calculated and recorded as a second pixel mean value.

Step 130, obtaining an image data slope value corresponding to any CIS image sensor according to the first exposure duration parameter, the first pixel mean value, the second exposure duration parameter and the second pixel mean value;

preferably, according to the formula k ═ (p)₂-p₁)/(gs₂-gs₁) Acquiring an image data slope value corresponding to any CIS image sensor;

wherein k is an image data slope value corresponding to any CIS image sensor, p₂Is the second pixel mean value, p₁Is the first pixel mean value, gs₂Is said second exposure duration parameter, gs₁Is the first exposure duration parameter.

And 140, acquiring a difference rate between any one CIS image sensor and a preset reference CIS image sensor according to an image data slope value corresponding to the CIS image sensor and an image data slope value corresponding to the preset reference CIS image sensor.

wherein α is the differenceThe difference rate k is the image data slope rate value corresponding to any CIS image sensor, k₀And setting the image data slope value corresponding to the preset reference CIS image sensor.

The preset reference CIS image sensor may select any one of the CIS image sensors, and obtains a corresponding image data slope value according to the steps 110 to 130.

According to the embodiment of the invention, by fixing the AD register parameter and the constant current source current parameter, when the constant current source exposure duration parameter is adjusted to be the first exposure duration parameter, any CIS image sensor is adopted to acquire image data and obtain the first pixel average value of the currently acquired image data; acquiring a second pixel mean value of the currently acquired image data by adjusting the constant current source exposure duration parameter as a second exposure duration parameter; acquiring an image data slope value corresponding to the CIS image sensor according to the first exposure duration parameter, the first pixel mean value, the second exposure duration parameter and the second pixel mean value; and acquiring the difference rate between the CIS image sensor and a preset reference CIS image sensor according to the image data slope value corresponding to the CIS image sensor and the image data slope value corresponding to the preset reference CIS image sensor. By the technical scheme, the problems that parameters of an AD chip and a constant current source chip need to be adjusted repeatedly before the CIS image sensor is used for collecting images due to the fact that differences of CIS image sensors in different batches are not quantified, a large amount of time is wasted, and the subsequent image collecting precision is influenced are solved, the parameter adjusting time is shortened, and the subsequent image collecting precision is improved.

Example two

Fig. 2 is a schematic flow chart of a difference detection method according to a second embodiment of the present invention, which is further optimized based on the above embodiments. The method specifically comprises the following steps:

step 210, acquiring image data through any CIS image sensor according to a preset AD register parameter, a preset constant current source current parameter and a first exposure duration parameter, and acquiring a first pixel mean value of the currently acquired image data;

step 220, acquiring image data through any CIS image sensor according to the preset AD register parameter, the preset constant current source current parameter and the second exposure duration parameter, and acquiring a second pixel mean value of the currently acquired image data;

preferably, acquiring image data according to the preset AD register parameter, the preset constant current source current parameter and the second exposure duration parameter by using any CIS image sensor, and acquiring a second pixel mean value of the currently acquired image data includes:

step 221, adjusting the constant current source exposure duration parameter adopted when image data is acquired last time according to a preset step length to obtain a current exposure duration parameter;

step 222, acquiring image data according to the preset AD register parameter, the preset constant current source current parameter and the current exposure duration parameter, and acquiring a current pixel mean value of the currently acquired image data;

step 223, judging whether the current pixel mean value meets a preset condition;

step 224, determining the current exposure duration parameter as the second exposure duration parameter, and the current pixel mean value as the second pixel mean value; or

And returning to execute the step of adjusting the exposure duration parameter adopted when the image data is acquired last time according to the preset step length.

Illustratively, the AD gain parameter is set to 1, the AD offset parameter is set to neither positive nor negative, the constant current source current parameter is set to 50% of the maximum current value of the constant current source, and the constant current source exposure duration parameter is set to 0 (i.e., the first exposure duration parameter gs)₁0), collecting gray level image data of the white paper, calculating the sum of pixel values of all pixel points in the obtained gray level image data, dividing the sum by the number of the pixel points to obtain an image data mean value, and recording the image data mean value as a first pixel mean value p₁。

And (3) keeping the fixed AD gain parameter, the AD bias parameter and the constant current source current parameter unchanged, and adjusting the constant current source exposure duration parameter by taking 20 as a preset step length. I represents the times of adjusting the constant current source exposure time length parameter, and the corresponding current exposure time length parameter is (20 ini) In that respect Under the parameter conditions, the CIS image sensor is used for collecting image data and calculating the mean value P of the current pixel_i。

Judging the current pixel mean value P_iWhether the preset condition 190 is not more than P_iLess than or equal to 210. When P is present_i< 190 or P_iWhen the pixel mean value P is more than 210, a preset step length is added on the basis of the exposure duration parameter adopted when the image data is acquired last time, and the next pixel mean value P is obtained_i+1And continuously judging whether the preset conditions are met. When 190 is less than or equal to P_iWhen the average value is less than or equal to 210, the current pixel mean value P is recorded_iIs p₂And recording the current exposure time length parameter (20 × i) as a second exposure time length parameter gs₂。

Step 230, according to the formula k ═ (p)₂-p₁)/(gs₂-gs₁) Acquiring an image data slope value corresponding to any CIS image sensor;

wherein k is an image data slope value corresponding to any CIS image sensor, p₂Is the second pixel mean value, p₁Is the first pixel mean value, gs₂Is said second exposure duration parameter, gs₁Is the first exposure duration parameter.

wherein α is the difference rate, k is the image data slope value corresponding to any CIS image sensor, and k is₀And setting the image data slope value corresponding to the preset reference CIS image sensor.

According to the method, when the AD register parameter and the constant current source current parameter are fixed and the constant current source exposure duration parameter is adjusted to be the first exposure duration parameter, any CIS image sensor is adopted to acquire image data and a first pixel mean value of the currently acquired image data is acquired; acquiring a current exposure duration parameter by dynamically adjusting the constant current source exposure duration parameter, acquiring a current pixel mean value of current acquired image data, and finally determining a second pixel mean value and a second exposure duration parameter according to a preset condition; calculating an image data slope value corresponding to the CIS image sensor according to a corresponding formula; and calculating the difference rate between the CIS image sensor and a preset reference CIS image sensor according to a corresponding formula. The problems that the parameters of an AD chip and a constant current source chip need to be adjusted repeatedly before the CIS image sensor is used for collecting images due to the fact that the differences of different batches of CIS image sensors are not quantified, a large amount of time is wasted, and the subsequent image collecting precision is influenced are solved, the parameter adjusting time is shortened, and the subsequent image collecting precision is improved.

EXAMPLE III

Specifically, the second pixel mean value obtaining module includes:

the exposure duration parameter adjusting unit is used for adjusting the exposure duration parameter adopted when the image data is acquired last time according to a preset step length to obtain a current exposure duration parameter;

a current pixel mean value obtaining unit, configured to obtain current pixel mean values of currently-collected image data according to the preset AD register parameter, the preset constant current source current parameter, and the current exposure duration parameter;

the judging unit is used for judging whether the current pixel mean value meets a preset condition or not; a determining unit, configured to determine that the current exposure duration parameter is the second exposure duration parameter when the current pixel mean value meets a preset condition, where the current pixel mean value is the second pixel mean value;

and the returning unit is used for returning to execute the step of adjusting the exposure duration parameter adopted when the image data is acquired last time according to the preset step length when the current pixel mean value does not meet the preset condition.

Preferably, the preset condition is that the image data mean is 190 or more and 210 or less.

Specifically, the image data slope value obtaining module is configured to:

according to the formula k ═ p₂-p₁)/(gs₂-gs₁) Acquiring an image data slope value corresponding to any CIS image sensor;

wherein k is an image data slope value corresponding to any CIS image sensor, p₂Is the second pixel mean value, p₁Is the first pixel mean value, gs₂Is said second exposure duration parameter, gs₁Is the first exposure duration parameter.

Specifically, the difference rate obtaining module is configured to:

wherein α is the difference rate, k is the image data slope value corresponding to any CIS image sensor, and k is₀And setting the image data slope value corresponding to the preset reference CIS image sensor.

The product can execute the difference detection method provided by any embodiment of the invention, and has corresponding functional modules and beneficial effects for executing the difference detection method.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.