CN111027424B - Fingerprint acquisition device and method and intelligent door lock - Google Patents
Fingerprint acquisition device and method and intelligent door lock Download PDFInfo
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- CN111027424B CN111027424B CN201911192986.6A CN201911192986A CN111027424B CN 111027424 B CN111027424 B CN 111027424B CN 201911192986 A CN201911192986 A CN 201911192986A CN 111027424 B CN111027424 B CN 111027424B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
- G06V40/1306—Sensors therefor non-optical, e.g. ultrasonic or capacitive sensing
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- G—PHYSICS
- G07—CHECKING-DEVICES
- G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
- G07C9/00—Individual registration on entry or exit
- G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
- G07C9/00563—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys using personal physical data of the operator, e.g. finger prints, retinal images, voicepatterns
Abstract
The invention discloses a fingerprint acquisition device and a method, wherein the fingerprint acquisition method comprises the following steps: acquiring a fingerprint image of a finger; calculating the average gray value of the fingerprint image and the difference value between the average gray value and a preset gray value; when the difference value exceeds a preset difference value range, calculating an adjustment value of the sampling gain parameter according to the difference value, and adjusting the sampling gain parameter; when the adjusted sampling gain parameter exceeds a limit value, prompting to change the pressure value pressed by the finger; re-acquiring the fingerprint image of the finger, and recording the times of acquiring the fingerprint image; and when the times of acquiring the fingerprint images reach preset times, determining the newly acquired fingerprint images as target fingerprint images. The invention also discloses a fingerprint acquisition device. The fingerprint acquisition device and the fingerprint acquisition method can improve the quality of the acquired image so as to meet the corresponding image characteristic requirements.
Description
Technical Field
The invention relates to the technical field of fingerprint identification, in particular to a fingerprint acquisition device and method and an intelligent door lock.
Background
Semiconductor fingerprint sensors used in current fingerprint sensors typically employ 8-bit pixel depth, i.e., 256 gray levels. If the fingerprint sensor is pressed with the same force, for the sensor with fixed parameters, the gray value of a fingerprint image acquired by the sensor is very large after the finger is pressed, and the image is displayed to be very shallow or even completely white; when a wet finger presses, the gray value of the fingerprint image acquired by the sensor is very small, and the image is displayed to be very deep or even completely black, so that the fingerprint image acquired by the fingerprint sensor cannot meet subsequent use requirements, and the problems of low fingerprint unlocking accuracy, low safety and the like are caused.
Disclosure of Invention
In order to solve the problems of low accuracy, low safety and the like of fingerprint unlocking equipment caused by low quality of the acquired fingerprints in the conventional fingerprint acquisition device, the invention provides a fingerprint acquisition device and a method, which specifically comprise the following steps:
a fingerprint acquisition method, the fingerprint acquisition method comprising:
acquiring a fingerprint image of a finger;
calculating the average gray value of the fingerprint image and the difference value between the average gray value and a preset gray value;
when the difference value exceeds a preset difference value range, calculating an adjustment value of the sampling gain parameter according to the difference value, and adjusting the sampling gain parameter;
when the adjusted sampling gain parameter exceeds a limit value, prompting to change the pressure value pressed by the finger;
re-acquiring the fingerprint image of the finger, and recording the times of acquiring the fingerprint image;
and when the times of acquiring the fingerprint images reach preset times, determining the newly acquired fingerprint images as target fingerprint images.
In some embodiments, after calculating the difference between the average gray-scale value and the preset gray-scale value, the method includes:
and when the difference value does not exceed the preset difference value range, determining the fingerprint image as a target fingerprint acquisition image.
In some embodiments, the difference in gray value and the adjustment value for the sampling gain parameter satisfy the following relationship:
adjustment value of sampling gain parameter = difference value of gray value × negative constant
When the difference value exceeds a preset difference value range, calculating an adjustment value of the sampling gain parameter according to the difference value, and adjusting the sampling gain parameter, wherein the adjustment value comprises the following steps:
when the difference value is larger than zero and the calculated adjustment value of the sampling gain parameter is smaller than zero, adjusting the sampling gain parameter to be smaller than the adjustment value according to the adjustment value of the sampling gain parameter;
or when the difference value is smaller than zero, and the adjustment value of the sampling gain parameter obtained by calculation is larger than zero, the sampling gain parameter is increased by the adjustment value according to the adjustment value of the sampling gain parameter.
In some embodiments, after the adjusting the sampling gain parameter, the method includes:
and when the adjusted sampling gain parameter does not exceed the limit value, re-acquiring the fingerprint image of the finger, and recording the times of acquiring the fingerprint image.
In some embodiments, the prompting to change the pressure value of the finger press when the adjusted sampling gain parameter exceeds a limit value includes:
when the adjusted sampling gain parameter exceeds the lower limit value of the sampling gain parameter, prompting to increase the pressure value pressed by the finger;
or when the adjusted sampling gain parameter exceeds the upper limit value of the sampling gain parameter, prompting to reduce the pressure value of the finger pressing.
In some embodiments, when the adjusted sampling gain parameter exceeds an upper limit value of the sampling gain parameter, the method includes:
prompting to dry the finger.
In some embodiments, after said re-acquiring the fingerprint image of the finger and recording the number of times the fingerprint image was acquired, the method comprises:
and when the times of acquiring the fingerprint image do not reach the preset times, recalculating the average gray value of the fingerprint image and the difference value between the average gray value and the preset gray value.
In some embodiments, before the acquiring the first fingerprint image of the finger, the method comprises:
acquiring a pressure value of finger pressing;
when the pressure value reaches a preset pressure value, acquiring a fingerprint image of the finger;
otherwise, prompting to increase the pressure value pressed by the finger and acquiring the pressure value pressed by the finger again.
A fingerprint acquisition device, the fingerprint acquisition device comprising: a fingerprint image acquisition unit and a processor;
the fingerprint image acquisition unit is used for acquiring a fingerprint image of a finger;
the processor is used for calculating an average gray value of the fingerprint image, calculating a difference value between the average gray value and a preset gray value, calculating an adjustment value of a sampling gain parameter, adjusting the sampling gain parameter, recording the times of acquiring the fingerprint image and determining a target fingerprint image.
An intelligence lock, intelligence lock includes foretell fingerprint acquisition device.
According to the fingerprint acquisition method, the sampling gain parameter of the fingerprint sensor is calculated and adjusted according to the gray value difference value between the average gray value of the acquired fingerprint image and the preset gray value, when the sampling gain parameter adjustment exceeds the limit value, the distance between the finger and the capacitor array of the fingerprint sensor is changed by reminding a user to increase or decrease the finger pressing force, so that the capacitance of each unit of the capacitor array of the fingerprint sensor is changed along with the change of the capacitance, the fingerprint image with the average gray value more meeting the requirements is acquired, in addition, the time of the fingerprint acquisition process is controlled by taking the number of times of acquiring the fingerprint image as the ending condition of the fingerprint acquisition process, the phenomenon that the fingerprint image of the finger is acquired for many times in order to simply improve the quality of the fingerprint image is avoided, the fingerprint acquisition process stays for a long time, and the fingerprint image acquisition efficiency is reduced.
Drawings
FIG. 1 is a schematic diagram illustrating steps of a fingerprint acquisition method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating steps of a fingerprint acquisition method according to another embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating steps of a fingerprint acquisition method according to another embodiment of the present invention;
fig. 4 is a schematic diagram of a fingerprint acquisition device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, a schematic step diagram of a fingerprint acquisition method provided in an embodiment of the present invention specifically includes the following steps:
step 12: a fingerprint image of a finger is acquired.
The fingerprint image of the finger can be acquired by a fingerprint sensor or other devices with corresponding functions, and the acquired fingerprint image can be an image with gray values or corresponding image parameters.
In a particular embodiment, the fingerprint sensor may start acquiring a fingerprint image of a finger after the finger presses the fingerprint sensor. Specifically, when a capacitive fingerprint sensor is used, the capacitance of each cell of the capacitive array of the capacitive sensor is different due to the unequal distances between the ridges and valleys of the fingerprint of the finger, and the fingerprint image of the finger can be obtained by acquiring the different capacitances of the cells of the capacitive sensor.
Step 14: and calculating the average gray value of the fingerprint image and the difference value between the average gray value and a preset gray value.
The average gray value of the fingerprint image refers to an average value of the gray values of the fingerprint image, and specifically, different images can be calculated by adopting corresponding algorithms; the preset gray value can be a preset value and is used for screening the image with the average gray value reaching the preset gray value; the difference is obtained by subtracting a preset gray value from the calculated average gray value of the fingerprint image, and it is noted that the difference is greater than zero when the calculated average gray value is greater than the preset gray value, and the difference is less than zero when the calculated average gray value is less than the preset gray value.
In a specific embodiment, after the fingerprint sensor acquires the fingerprint image of the finger, the processor starts to calculate an average gray value of the fingerprint image according to a corresponding algorithm, and then subtracts a preset gray value from the average gray value to obtain a difference value between the average gray value and the preset gray value.
Step 16: and when the difference value exceeds a preset difference value range, calculating an adjustment value of the sampling gain parameter according to the difference value, and adjusting the sampling gain parameter.
The preset difference range can be an interval value, and the exceeding of the preset difference range means that the difference value is not within the preset difference interval range; the sampling gain parameter is a parameter when the fingerprint sensor acquires a fingerprint image; the calculating of the adjustment value of the sampling gain parameter according to the difference value may be that a numerical relationship exists between a gray value difference value of the fingerprint image and the sampling gain parameter, and the adjustment value of the sampling gain parameter to be adjusted may be calculated according to the gray value difference value of the image; and the step of adjusting the sampling gain parameter refers to adjusting the sampling gain parameter to a target value according to an adjustment value calculated by a processor.
In a specific embodiment, assuming that the average gray value calculated from the fingerprint image obtained in the previous step may be 120 and the preset gray value is 160, and the preset difference range in this step may be ± 10, the difference obtained by subtracting the preset gray value 160 from the average gray value 120 is-40, obviously, the difference exceeds the preset difference range, so it is necessary to calculate the adjustment value of the sampling gain parameter according to the difference.
In a specific embodiment, the difference between the gray-level values of the fingerprint image and the sampling gain parameter may conform to the following relationship:
the adjustment value of the sampling gain parameter = the difference value of the gray value x the negative constant, wherein the negative constant is a constant less than zero, the adjustment value of the sampling gain parameter is a numerical value that the current sampling gain parameter needs to be adjusted up or down, when the difference value of the gray value is greater than zero, the adjustment value of the sampling gain parameter calculated according to the relational expression will be less than zero, indicating that the current sampling gain parameter needs to be adjusted down by a corresponding adjustment value, and when the difference value of the gray value is less than zero, the adjustment value of the sampling gain parameter calculated according to the relational expression will be greater than zero, indicating that the current sampling gain parameter needs to be adjusted up by a corresponding adjustment value.
In a specific embodiment, the difference value of the gray scale value may be-40, the negative constant may be-1, and then the adjustment value of the sampling gain parameter obtained according to the above-mentioned relational expression is 40, which indicates that the current sampling gain parameter should be increased by 40, and similarly, when the difference value of the gray scale value is 40, the negative constant may be-1, and then the adjustment value of the sampling gain parameter obtained according to the above-mentioned relational expression is-40, which indicates that the current sampling gain parameter should be decreased by 40.
In a specific embodiment, the current sampling gain parameter may be 80, and in the above step, when the adjustment value of the sampling gain parameter is calculated to be-40, the processor issues an instruction to reduce the current sampling gain parameter by 40, and adjust the current sampling gain parameter to 40; and when the adjustment value of the sampling gain parameter is 40, the processor sends an instruction to increase the current sampling gain parameter by 40 and adjust the current sampling gain parameter to 120.
Step 18: and when the adjusted sampling gain parameter exceeds a limit value, prompting to change the pressure value pressed by the finger.
The limit value of the sampling gain parameter can be an adjustable upper limit value or a lower limit value of the sampling gain parameter due to the self limitations of different types of sensors, or can be a preset upper limit value or a preset lower limit value of the sampling gain parameter; the pressure value that the finger was pressed is when the finger pressed or touched the fingerprint sensor, and the effort that the finger applyed to the fingerprint sensor.
In a specific embodiment, assuming that the sampling gain parameter is 40 after being adjusted, and the preset sampling gain parameter has an upper limit value of 100 and a lower limit value of 60, and the adjusted sampling gain parameter value 40 exceeds the lower limit value, the user is prompted to increase the pressing force of the finger, and the distance between the finger and the capacitor array of the fingerprint sensor is reduced by increasing the pressure value, so that the capacitance of each cell of the capacitor array of the fingerprint sensor changes along with the finger, and a fingerprint image with a smaller average gray value is obtained. When the acquisition gain parameter is adjusted to 120, the upper limit value of the preset sampling gain parameter is 100, and the lower limit value of the preset sampling gain parameter is 60, and the adjusted sampling gain parameter value 120 exceeds the upper limit value, a user is prompted to reduce the pressing pressure of the finger, the distance between the finger and the capacitor array of the fingerprint sensor is increased by reducing the pressure value, so that the capacitance of each unit of the capacitor array of the fingerprint sensor is changed along with the change of the capacitance, and the fingerprint image with a larger average gray value is acquired.
Step 20: and re-acquiring the fingerprint image of the finger, and recording the times of acquiring the fingerprint image.
The re-acquiring the fingerprint image of the finger may be to acquire the fingerprint image of the finger again by using the fingerprint sensor after the sampling gain parameter of the fingerprint sensor is adjusted or the user is prompted to change the pressing pressure value of the finger; the recording of the number of times of acquiring the fingerprint image refers to recording the number of times of acquiring the fingerprint image by using a processor or other counters, and increasing the value by 1 every 1-time increment of the process of acquiring the fingerprint image.
In a specific embodiment, the fingerprint sensor may acquire the fingerprint image of the finger after the sampling gain parameter of the fingerprint sensor is adjusted or the user changes the pressing force of the finger again, and record the number of times of acquiring the fingerprint image in this operation, where the number of times is recorded as 1 when the fingerprint sensor acquires the fingerprint image for the first time, and the number of times is recorded as 2 when the fingerprint sensor acquires the fingerprint image for the second time.
Step 22: and when the times of acquiring the fingerprint images reach preset times, determining the newly acquired fingerprint images as target fingerprint images.
The preset times can be preset times determined according to factors such as the processing time of the sensor and the like, and are mainly used for controlling the fingerprint acquisition time and avoiding overlong acquisition time; and stopping the related work of fingerprint acquisition when the reacquired fingerprint image is determined to be the target fingerprint image, and storing the reacquired fingerprint image.
In this embodiment, a sampling gain parameter of the fingerprint sensor is calculated and adjusted according to a gray value difference between an average gray value of an acquired fingerprint image and a preset gray value, and when the sampling gain parameter adjustment exceeds a limit value, a user is reminded to increase or decrease the finger pressing force to change the distance between the finger and a capacitor array of the fingerprint sensor, so that the capacitance of each unit of the capacitor array of the fingerprint sensor changes along with the change of the sampling gain parameter, so as to acquire the fingerprint image with the average gray value more meeting the requirement, thereby improving the accuracy and the safety of the fingerprint unlocking device, and in addition, the number of times of acquiring the fingerprint image is used as an end condition of the fingerprint acquisition process, thereby controlling the time of the fingerprint acquisition process, avoiding acquiring the fingerprint image of the finger too many times in order to improve the quality of the pure fingerprint image, thereby staying in the fingerprint acquisition process for a long time, and reducing the fingerprint acquisition efficiency.
The present invention also provides another embodiment, in which the same steps and methods as those in the above embodiment exist, and therefore, in this embodiment, the same parts as those in the above embodiment are not described again, and for related descriptions, reference may be made to the description in the above embodiment. Referring to fig. 2, in the present embodiment, the fingerprint acquisition method includes the following steps:
step 12: a fingerprint image of a finger is acquired.
Step 14: and calculating the average gray value of the fingerprint image and the difference value between the average gray value and a preset gray value.
Step 161: and judging whether the difference value is larger than zero.
The difference value is the average gray value of the fingerprint image and the gray value difference value between the average gray value and a preset gray value; the judgment of whether the difference is greater than zero may be that a value obtained by subtracting 0 from the difference is a positive value, the judgment is yes, and otherwise, the judgment is no.
In a specific embodiment, the difference value of the gray values may be 40, and then 40 is obtained by subtracting 0 from 40, and at this time, if 40 is a positive number, it is determined as yes; and when the difference value of the gray values is-40, subtracting 0 from-40 to obtain-40, and when the-40 is a non-positive number, judging that the gray values are not positive.
Step 162: and adjusting the sampling gain parameter to be smaller than the adjustment value according to the adjustment value of the sampling gain parameter, wherein the adjustment value of the sampling gain parameter is smaller than zero.
In a specific embodiment, the difference between the gray-level values of the fingerprint image and the sampling gain parameter may conform to the following relationship:
the adjustment value of the sampling gain parameter = the difference value of the gray value × the negative constant, where the negative constant is a constant smaller than zero, and the adjustment value of the sampling gain parameter is a numerical value of the current sampling gain parameter that needs to be adjusted up or down, and specifically, when the difference value of the gray value is greater than zero, the adjustment value of the sampling gain parameter calculated according to the above relation is smaller than zero, which indicates that the current sampling gain parameter needs to be adjusted down by a corresponding adjustment value.
In a specific embodiment, when the difference value of the gray scale values is 40 and the negative constant may be-1, the adjustment value of the sampling gain parameter obtained according to the above relation is-40, which indicates that the current sampling gain parameter should be decreased by 40.
Step 163: and the calculated adjustment value of the sampling gain parameter is larger than zero, and the sampling gain parameter is increased by the adjustment value according to the adjustment value of the sampling gain parameter.
When the difference value of the gray value is less than zero, the obtained adjustment value of the sampling gain parameter calculated according to the relational expression is greater than zero, which indicates that the current sampling gain parameter needs to be increased by the corresponding adjustment value
In a specific embodiment, the difference value of the gray scale values may be-40, the negative constant may be-1, and if the adjustment value of the sampling gain parameter obtained according to the above relation is 40, it indicates that the current sampling gain parameter should be increased by 40.
Step 181: and judging whether the adjusted sampling gain parameter exceeds a limit value or not.
The limit value of the sampling gain parameter may be an upper limit value or a lower limit value of the sampling gain parameter which is adjustable due to the limitations of the sensors of different types, or may be an upper limit value or a lower limit value of a preset sampling gain parameter;
in a specific embodiment, assuming that the sampling gain parameter is 40 after being adjusted, and the upper limit value of the preset sampling gain parameter is 100 and the lower limit value is 60, the adjusted sampling gain parameter value 40 exceeds the lower limit value 60, and it is determined that the adjusted sampling gain parameter value exceeds the lower limit value; when the acquisition gain parameter is adjusted to 120, and the upper limit value of the preset sampling gain parameter is 100 and the lower limit value is 60, the adjusted sampling gain parameter value 120 exceeds the upper limit value 100, and the value is determined to exceed the upper limit value. When the sampling gain parameter is 80 after adjustment, the determination is no, and the process proceeds to step 20 directly.
Step 182: and when the adjusted sampling gain parameter exceeds the lower limit value of the sampling gain parameter, prompting to increase the pressure value pressed by the finger.
In a specific embodiment, assuming that the sampling gain parameter may be 40 after being adjusted, since 40 is smaller than the lower limit value 60, it is determined that the sampling gain parameter exceeds the lower limit value of the sampling gain parameter, the user is prompted to increase the degree of pressing the finger, and the distance between the finger and the capacitor array of the fingerprint sensor is reduced by increasing the pressure value, so that the capacitance of each cell of the capacitor array of the fingerprint sensor changes along with the change of the pressure value, so as to obtain a fingerprint image with a smaller average gray value.
Step 183: and when the adjusted sampling gain parameter exceeds the upper limit value of the sampling gain parameter, prompting to reduce the pressure value of the finger pressing.
In a specific embodiment, assuming that the sampling gain parameter may be 120 after being adjusted, since 120 is greater than the upper limit value of 100, it is determined that the sampling gain parameter exceeds the upper limit value of the sampling gain parameter, the user is prompted to reduce the pressing force of the finger, and the distance between the finger and the capacitor array of the fingerprint sensor is increased by reducing the pressing force, so that the capacitance of each cell of the capacitor array of the fingerprint sensor changes accordingly, so as to obtain a fingerprint image with a larger average gray value.
Step 20: and re-acquiring the fingerprint image of the finger, and recording the times of acquiring the fingerprint image.
Step 221: and judging whether the times of acquiring the fingerprint image reach preset times or not.
The preset times can be preset times determined according to factors such as processing time of the sensor and the like, and are mainly used for controlling fingerprint acquisition time and improving fingerprint acquisition efficiency.
In a specific embodiment, the preset number of times may be set to 2, when the recorded number of times of acquiring the fingerprint image reaches 2, it is determined that the number of times of acquiring the fingerprint image reaches the preset number of times, otherwise, it is determined that the number of times of acquiring the fingerprint image does not reach the preset number of times, and the step 14 is executed again to calculate the average gray value of the fingerprint image.
Step 222: and determining the re-acquired fingerprint image as a target fingerprint image.
The determining that the reacquired fingerprint image is the target fingerprint image may be a related task of stopping fingerprint acquisition, and saving the reacquired fingerprint image.
In this embodiment, a sampling gain parameter of the fingerprint sensor is calculated and adjusted according to a gray value difference between an average gray value of an acquired fingerprint image and a preset gray value, and when the sampling gain parameter adjustment exceeds a limit value, a user is reminded to increase or decrease the finger pressing force to change the distance between the finger and a capacitor array of the fingerprint sensor, so that the capacitance of each unit of the capacitor array of the fingerprint sensor changes along with the change of the sampling gain parameter, the fingerprint image with the average gray value more meeting the requirement is acquired, the accuracy and the safety of the fingerprint unlocking device are improved, and in addition, the fingerprint image acquisition efficiency is improved by taking the number of times of acquiring the fingerprint image as an end condition of the fingerprint acquisition process. When the times of acquiring the fingerprint images are within the preset times, the fingerprint image acquisition process is carried out again, so that the characteristics of the acquired fingerprint images meet the requirements as far as possible, and the accuracy of fingerprint unlocking is further improved.
The present invention also provides another embodiment, in which the same steps and methods as those in the above embodiment exist, and therefore, in this embodiment, the same parts as those in the above embodiment are not described again, and for related descriptions, reference may be made to the description in the above embodiment. Referring to fig. 3, in the present embodiment, the fingerprint acquisition method includes the following steps:
step 10: and acquiring the pressure value of the finger pressing.
The acquiring of the pressure value of the finger pressing may be acquiring the pressure value of the finger pressing by using a pressure detection function of a fingerprint sensor.
In a specific embodiment, if the pressure value of the finger pressing detected by the fingerprint sensor is 100N, the obtained pressure value of the finger pressing is determined to be 100N.
Step 111: and judging whether the pressure value reaches a preset pressure value or not.
The preset pressure value may be a preset pressure value preset according to a requirement for acquiring a fingerprint image.
In a specific embodiment, the preset pressure value may be 80N, and when the obtained pressure value pressed by the finger is 100N, and the obtained pressure value reaches the preset pressure value, it is determined that the pressure value is yes, step 12 is performed to obtain the fingerprint image of the finger, otherwise, it is determined that the pressure value is no.
Step 112: and prompting to increase the pressure value pressed by the finger.
The prompt for increasing the pressure value of the finger pressing can be used for prompting the user to increase the finger pressing strength through screen display or vibration reminding or voice prompt and other modes.
In a specific embodiment, when the pressure value does not reach the preset pressure value, and if the judgment result is no, the user may be prompted on the display screen to increase the finger pressing force, so as to increase the pressure value, and the pressure value reaches the preset pressure value.
Step 12: a fingerprint image of a finger is acquired.
Step 14: and calculating the average gray value of the fingerprint image and the difference value between the average gray value and a preset gray value.
Step 151: and judging whether the difference value exceeds a preset difference value range.
The preset difference range may be a preset difference range determined according to the characteristic requirements of the system for the target fingerprint image.
In a specific embodiment, the preset difference range may be ± 30, when the difference is 40, the difference is determined to be beyond the preset difference range, and if the output is yes, step 161 is executed to continuously determine whether the difference is greater than zero. When the difference is-20, judging that the difference does not exceed the preset difference range, and outputting no.
Step 152: and determining the fingerprint image as a target fingerprint image.
The determining that the fingerprint image is the target fingerprint image may be stopping the related work of fingerprint acquisition, and storing the acquired fingerprint image.
In a specific implementation manner, when the judgment result shows that the difference does not exceed the preset difference range, and the output result shows that the difference does not exceed the preset difference range, the related work of fingerprint acquisition is stopped, and the acquired fingerprint image is stored.
Step 161: and judging whether the difference value is larger than zero.
Step 162: and adjusting the sampling gain parameter to be smaller than the adjustment value according to the adjustment value of the sampling gain parameter, wherein the adjustment value of the sampling gain parameter is smaller than zero.
Step 163: and the calculated adjustment value of the sampling gain parameter is larger than zero, and the sampling gain parameter is increased by the adjustment value according to the adjustment value of the sampling gain parameter.
Step 181: and judging whether the adjusted sampling gain parameter exceeds a limit value.
Step 182: and when the adjusted sampling gain parameter exceeds the lower limit value of the sampling gain parameter, prompting to increase the pressure value pressed by the finger.
Step 183: and when the adjusted sampling gain parameter exceeds the upper limit value of the sampling gain parameter, prompting to reduce the pressure value of the finger pressing.
Step 20: and re-acquiring the fingerprint image of the finger, and recording the times of acquiring the fingerprint image.
Step 221: and judging whether the times of acquiring the fingerprint image reach preset times or not.
Step 222: determining the re-acquired fingerprint image as a target fingerprint image.
In this embodiment, before acquiring a fingerprint image, the quality of the acquired fingerprint image is improved by controlling the pressure value of the acquired fingerprint image, and then the sampling gain parameter of the fingerprint sensor is calculated and adjusted according to the gray value difference between the average gray value of the acquired fingerprint image and the preset gray value, and when the sampling gain parameter adjustment exceeds the limit value, the distance between the finger and the capacitor array of the fingerprint sensor is changed by reminding a user to increase or decrease the finger pressing force, so that the capacitance of each unit of the capacitor array of the fingerprint sensor changes accordingly, so as to acquire the fingerprint image with the average gray value more meeting the requirements, or the finger is prompted to be wiped dry, so as to acquire the fingerprint image again, thereby improving the accuracy and the safety of the fingerprint unlocking device. In addition, the fingerprint image acquisition efficiency is improved by taking the times of acquiring the fingerprint images as the end conditions of the fingerprint acquisition process; when the times of acquiring the fingerprint images are within the preset times, the acquisition process of the fingerprint images is carried out again, so that the image characteristics can meet the requirements as much as possible, and the accuracy of fingerprint unlocking is further improved.
The embodiment of the present invention further provides a fingerprint acquisition apparatus 30, referring to fig. 4, the fingerprint acquisition apparatus includes a fingerprint image acquisition unit 31 and a processor 32; wherein the fingerprint image acquiring unit 31 is used for acquiring a fingerprint image of a finger; the processor 32 is configured to calculate an average gray value of the fingerprint image, calculate a difference between the average gray value and a preset gray value, calculate an adjustment value of a sampling gain parameter, adjust the sampling gain parameter, record the number of times of acquiring the fingerprint image, and determine a target fingerprint image.
The embodiment of the invention also provides the intelligent door lock, which comprises a fingerprint acquisition device. The fingerprint acquisition device has the same or similar functions as the fingerprint acquisition device 30 provided in the above embodiment, and the description thereof is omitted.
Although the invention has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. The present invention includes all such modifications and alterations and is limited only by the scope of the appended claims. In particular regard to the various functions performed by the above described components, the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the specification. In addition, while a particular feature of the specification may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for a given or particular application. Furthermore, to the extent that the terms "includes," has, "" contains, "or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term" comprising. Further, it is understood that reference to "a plurality" herein means two or more. For the steps mentioned herein, the numerical suffixes are merely used for clearly expressing the embodiments, and for easy understanding, the order of execution of the steps is not fully represented, and the logical relationship should be set as consideration.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent flow transformations made by using the contents of the specification and the drawings, such as the mutual combination of technical features between various embodiments, or the direct or indirect application to other related technical fields, are included in the scope of the present invention.
Claims (9)
1. A fingerprint acquisition method, comprising:
acquiring a fingerprint image of a finger;
calculating the average gray value of the fingerprint image and the difference value between the average gray value and a preset gray value;
when the difference exceeds a preset difference range, calculating an adjustment value of a sampling gain parameter according to the difference, and adjusting the sampling gain parameter, wherein the method comprises the following steps: when the difference value is larger than zero and the calculated adjustment value of the sampling gain parameter is smaller than zero, adjusting the sampling gain parameter to be smaller than the adjustment value according to the adjustment value of the sampling gain parameter; or when the difference value is less than zero, the calculated adjustment value of the sampling gain parameter is greater than zero, and the sampling gain parameter is increased by the adjustment value according to the adjustment value of the sampling gain parameter; wherein the difference value and the adjustment value of the sampling gain parameter satisfy the following relationship: the adjustment value of the sampling gain parameter = the difference value of the gray value × the negative constant;
when the adjusted sampling gain parameter exceeds a limit value, prompting to change the pressure value pressed by the finger;
re-acquiring the fingerprint image of the finger, and recording the times of acquiring the fingerprint image;
and when the times of acquiring the fingerprint images reach preset times, determining the newly acquired fingerprint images as target fingerprint images.
2. The fingerprint collection method according to claim 1, wherein after calculating the difference between the average gray-level value and a preset gray-level value, the method comprises:
and when the difference value does not exceed the preset difference value range, determining the fingerprint image as a target fingerprint acquisition image.
3. The fingerprint acquisition method of claim 1, wherein after the adjusting the sampling gain parameter, the method comprises:
and when the adjusted sampling gain parameter does not exceed the limit value, re-acquiring the fingerprint image of the finger, and recording the times of acquiring the fingerprint image.
4. The fingerprint acquisition method according to claim 1 or 3, wherein prompting to change the pressure value of the finger press when the sampling gain parameter after the adjustment exceeds a limit value comprises:
when the adjusted sampling gain parameter exceeds the lower limit value of the sampling gain parameter, prompting to increase the pressure value pressed by the finger;
or when the adjusted sampling gain parameter exceeds the upper limit value of the sampling gain parameter, prompting to reduce the pressure value of the finger pressing.
5. The fingerprint acquisition method according to claim 4, wherein when the sampling gain parameter after the adjustment exceeds the upper limit value of the sampling gain parameter, the method comprises:
and prompting to dry the finger.
6. A fingerprint acquisition method according to claim 1 or 3, wherein after said re-acquiring the fingerprint image of said finger and recording said number of times of acquiring the fingerprint image, said method comprises:
and when the times of acquiring the fingerprint image do not reach the preset times, recalculating the average gray value of the fingerprint image and the difference value between the average gray value and the preset gray value.
7. Fingerprint acquisition method according to claim 1, wherein before said acquisition of a first fingerprint image of a finger, the method comprises:
acquiring a pressure value pressed by a finger;
when the pressure value reaches a preset pressure value, acquiring a fingerprint image of the finger;
otherwise, prompting to increase the pressure value pressed by the finger and acquiring the pressure value pressed by the finger again.
8. A fingerprint acquisition apparatus, comprising: a fingerprint image acquisition unit and a processor;
the fingerprint image acquisition unit is used for acquiring a fingerprint image of a finger;
the processor is configured to calculate an average gray value of the fingerprint image by the fingerprint acquisition method according to any one of claims 1 to 7, calculate a difference between the average gray value and a preset gray value, calculate an adjustment value of a sampling gain parameter, adjust the sampling gain parameter, record the number of times the fingerprint image is acquired, and determine a target fingerprint image.
9. An intelligent door lock, characterized in that the intelligent door lock comprises the fingerprint acquisition device of claim 8.
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| JP2776340B2 (en) * | 1995-11-08 | 1998-07-16 | 日本電気株式会社 | Fingerprint feature extraction device |
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| CN106258009B (en) * | 2015-04-16 | 2019-06-21 | 华为技术有限公司 | A kind of method, fingerprint capturer and terminal acquiring fingerprint |
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| CN105677082B (en) * | 2015-12-29 | 2017-08-04 | 比亚迪股份有限公司 | Fingerprint pressure testing method and its application process and corresponding intrument based on terminal device |
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