CN117133215A

CN117133215A - Method, chip, electronic device and readable storage medium for determining gray scale value

Info

Publication number: CN117133215A
Application number: CN202310187882.6A
Authority: CN
Inventors: 郑子易
Original assignee: Honor Device Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2023-02-20
Filing date: 2023-02-20
Publication date: 2023-11-28

Abstract

The application relates to the technical field of display, and provides a method, a chip, electronic equipment and a readable storage medium for determining gray scale values. The method comprises the following steps: acquiring an initial gray level value of the display device under an initial brightness level, wherein the initial brightness level is used for representing the brightness level of the display device in the current display state, and the initial gray level value is used for representing the brightness of the display device under the initial brightness level; when the fingerprint light spots are excited, a target gray-scale mapping coefficient and a reference brightness level are obtained, wherein the target gray-scale mapping coefficient is a corresponding coefficient when the display device is switched from the initial brightness level to the reference brightness level; and determining a target gray scale value according to the target gray scale mapping coefficient and the initial gray scale value, wherein the target gray scale value is used for displaying the background picture according to the target gray scale value under the reference brightness level by the display device. The method can avoid brightness jump of the background picture.

Description

Method, chip, electronic device and readable storage medium for determining gray scale value

Technical Field

The present application relates to the field of electronic technology, and in particular, to a method, a chip, an electronic device, and a readable storage medium for determining a gray scale value.

Background

With the development of terminal technology, a mode of unlocking a screen by fingerprints is increasingly and widely applied to terminal equipment. When the user needs to unlock the screen, the user can click the screen or press a switch button to excite the fingerprint light spot. At this time, the screen displays an icon of the fingerprint light spot. The user may enter a fingerprint at the icon of the fingerprint spot for unlocking. In the process of pressing by a user, a camera below the screen can shoot a fingerprint image pressed by the user and recognize the fingerprint image.

In general, in order to increase the recognition rate of fingerprint images, the dimming mode of the screen needs to be entered into a direct current mode (DC mode) so that the excitation of the spot is in a high brightness mode. In the DC mode, the brightness level of the screen becomes high. If the brightness level of the background picture before the light spot is excited is lower, after the light spot is excited, the brightness level of the background picture enters a high brightness level corresponding to the DC mode due to excitation of the light spot, and the background picture suddenly lightens, so that the experience of a user is affected.

Disclosure of Invention

The application provides a method, a device, a chip, electronic equipment, a computer readable storage medium and a computer program product for determining gray scale values, which can avoid brightness jump of a background picture when fingerprint light spots are excited.

In a first aspect, a method for determining a gray scale value is provided, including: acquiring an initial gray scale value of a display device under an initial brightness level, wherein the initial brightness level is used for representing the brightness level of the display device in a current display state, and the initial gray scale value is used for representing the brightness of the display device under the initial brightness level; when a fingerprint light spot is excited, a target gray-scale mapping coefficient and a reference brightness level are obtained, wherein the target gray-scale mapping coefficient is a coefficient corresponding to the display device when the initial brightness level is switched to the reference brightness level; determining a target gray scale value according to the target gray scale mapping coefficient and the initial gray scale value, wherein the difference value between the brightness of the initial gray scale value under the initial brightness level and the brightness of the target gray scale value under the reference brightness level is smaller than a preset threshold value, and the target gray scale value is used for displaying a background picture according to the target gray scale value under the reference brightness level by the display device.

When the fingerprint light spot is excited, the display driving chip (Display Drive Intergrated Circuit Chip, DDIC) obtains a target gray level mapping coefficient corresponding to the initial brightness level entering the reference brightness level, determines a new gray level value which enables the brightness of the background picture to be unchanged or changed little under the reference brightness level according to the target gray level mapping coefficient and the initial gray level value, and then displays the background picture under the reference brightness level by adopting the new gray level value, thereby avoiding the brightness mutation of the background picture when the light spot is excited. In the method, although the brightness level is changed, a screen is not required to be switched to a new frame rate, a set of registers are not required to be occupied to store brightness parameters corresponding to the new frame rate, and the registers are not required to be added, so that the cost is prevented from increasing.

In some possible implementations, the target gray-scale mapping coefficient is one of a plurality of gray-scale mapping coefficients, and the plurality of gray-scale mapping coefficients and a plurality of brightness levels form a mapping relationship, where the plurality of brightness levels includes the initial brightness level.

In some possible implementations, the reference brightness level is a highest brightness level of the display device, and the brightness corresponding to the reference brightness level is the highest brightness displayed by the display device.

When the fixed high brightness level is used as the reference brightness level when the fingerprint light spots are excited, the brightness curve always keeps a state close to a straight line, namely the brightness is stable, and the unlocking success rate can be ensured.

In some possible implementations, the reference brightness level is a display brightness value DBV4000, and the highest brightness is 1000 nits.

In some possible implementations, the reference brightness level is used to characterize a brightness level threshold at which a dimming mode of the display device switches between a multi-pulse modulation mode and a direct current mode.

The range between DBV0 and the reference luminance level is called the alpha (alpha) interval. Setting the reference brightness level to a brightness level threshold that characterizes switching of the dimming mode of the display device between the multi-pulse modulation mode and the direct current mode may compress the alpha interval. The compression alpha interval can enable the dimming mode of the display device to be in a DC mode when the fingerprint light spots are lightened, ensures the fingerprint unlocking rate, and can enable the fineness of brightness change control to be improved, avoids brightness jump of background pictures and improves the display effect.

In some possible implementations, the brightness level threshold is the display brightness value DBV1102.

In some possible implementations, the target grayscale mapping coefficient is a value between 0 and 1 when the initial luminance level is less than the reference luminance level.

In some possible implementations, the target grayscale mapping coefficient is 1 when the initial luminance level is greater than or equal to the reference luminance level.

In some possible implementations, the target grayscale value is equal to the initial grayscale value when the initial luminance level is greater than or equal to the reference luminance level.

After the alpha interval is compressed, the display device can directly display the initial gray scale value at the initial brightness level in the adjustment range of the DBV outside the alpha interval. For example, when the α interval is DBV0-DBV1102, that is, the α interval corresponds to a luminance below 90nit, if the luminance in the initial state has exceeded 90nit, that is, the initial luminance level is greater than DBV1102, the luminance level at this time may meet the fingerprint unlocking requirement, and the display device may display the background picture directly with an initial luminance level and an initial gray level that are greater than DBV1102 without switching to a higher luminance level. Since the brightness of the initial state exceeds 90nit, the brightness of the excited fingerprint light spot can be accurately unlocked, and the brightness level does not need to be improved any more, so that the initial gray scale value in the initial state is multiplexed. Alternatively, the display device may maintain an initial brightness level and display with an initial gray scale value; or dynamically updating the reference brightness level to the initial brightness level, and simultaneously obtaining a target gray scale value according to the target gray scale mapping coefficient of 1, wherein the obtained target gray scale value is equal to the initial gray scale value, so that the multiplexing of the initial gray scale value is realized. In the multiplexing process, the frame rate of the display device in display is not required to be switched, and a special register is not required to be occupied independently to store the brightness parameters, so that the resource waste of the register is avoided.

In some possible implementations, the initial gray level value is a first power of a gamma coefficient of the first ratio of the target gray level value, which is the target gray level mapping coefficient.

In some possible implementations, the gamma coefficient is 2.2.

In a second aspect, an apparatus for determining a gray scale value is provided, which includes a unit composed of software and/or hardware, where the unit is configured to perform any one of the methods in the first aspect.

In a third aspect, there is provided an electronic device, comprising: a processor, a memory, and an interface; the processor, the memory and the interface cooperate with each other to enable the electronic device to execute any one of the methods according to the first aspect.

In a fourth aspect, an embodiment of the present application provides a chip, including a processor; the processor is configured to read and execute a computer program stored in the memory to perform any one of the methods according to the first aspect.

Optionally, the chip further comprises a memory, and the memory is connected with the processor through a circuit or a wire.

Further optionally, the chip further comprises a communication interface.

In a fifth aspect, there is provided a computer readable storage medium having stored therein a computer program which, when executed by a processor, causes the processor to perform any one of the methods according to the first aspect.

In a sixth aspect, there is provided a computer program product comprising: computer program code which, when run on an electronic device, causes the electronic device to carry out any one of the methods of the first aspect.

Drawings

Fig. 1 is a schematic structural diagram of an example of a terminal device 100 according to an embodiment of the present application;

fig. 2 is a software architecture block diagram of a terminal device 100 provided in an embodiment of the present application;

FIG. 3 is a schematic diagram of an exemplary software architecture according to an embodiment of the present application;

FIG. 4 is a flowchart illustrating an exemplary method for determining gray scale values according to an embodiment of the present application;

FIG. 5 is a schematic diagram illustrating an interface operation of a fingerprint spot according to an embodiment of the present application;

fig. 6 is a schematic diagram of an example of an interval a with a highest reference brightness level according to an embodiment of the present application;

FIG. 7 is a graph showing an example of brightness at a highest reference brightness level according to an embodiment of the present application;

fig. 8 is a schematic distribution diagram of an alpha interval and a Gamma multiplexing interval according to an embodiment of the present application;

FIG. 9 is a graph showing an example of dynamic change of a reference brightness level according to an embodiment of the present application;

FIG. 10 is a schematic diagram of an example of DBV and brightness curves and gamma curves according to an embodiment of the present application;

FIG. 11 is a flowchart illustrating a method for determining gray scale values according to another embodiment of the present application;

fig. 12 is a schematic structural diagram of an apparatus for determining gray scale values according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application. Wherein, in the description of the embodiments of the present application, unless otherwise indicated, "/" means or, for example, a/B may represent a or B; "and/or" herein is merely an association relationship describing an association object, and means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. In addition, in the description of the embodiments of the present application, "plurality" means two or more than two.

The terms "first," "second," "third," and the like, are used below for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", or a third "may explicitly or implicitly include one or more such feature.

The method for determining the gray scale value provided by the embodiment of the application can be applied to terminal equipment such as mobile phones, tablet computers, wearable equipment, vehicle-mounted equipment, augmented reality (augmented reality, AR)/Virtual Reality (VR) equipment, notebook computers, ultra-mobile personal computer (UMPC), netbooks, personal digital assistants (personal digital assistant, PDA) and the like, and the embodiment of the application does not limit the specific types of the terminal equipment.

Fig. 1 is a schematic structural diagram of an exemplary terminal device 100 according to an embodiment of the present application. The terminal device 100 may include a processor 110, an external memory interface 120, an internal memory 121, a universal serial bus (universal serial bus, USB) interface 130, a charge management module 140, a power management module 141, a battery 142, an antenna 1, an antenna 2, a mobile communication module 150, a wireless communication module 160, an audio module 170, a speaker 170A, a receiver 170B, a microphone 170C, an earphone interface 170D, a sensor module 180, keys 190, a motor 191, an indicator 192, a camera 193, a display 194, and a subscriber identity module (subscriber identification module, SIM) card interface 195, etc. The sensor module 180 may include a pressure sensor 180A, a gyro sensor 180B, an air pressure sensor 180C, a magnetic sensor 180D, an acceleration sensor 180E, a distance sensor 180F, a proximity sensor 180G, a fingerprint sensor 180H, a temperature sensor 180J, a touch sensor 180K, an ambient light sensor 180L, a bone conduction sensor 180M, and the like.

It is to be understood that the structure illustrated in the embodiment of the present application does not constitute a specific limitation on the terminal device 100. In other embodiments of the application, terminal device 100 may include more or less components than illustrated, or certain components may be combined, or certain components may be split, or different arrangements of components. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

The processor 110 may include one or more processing units, such as: the processor 110 may include an application processor (application processor, AP), a modem processor, a graphics processor (graphics processing unit, GPU), an image signal processor (image signal processor, ISP), a controller, a memory, a video codec, a digital signal processor (digital signal processor, DSP), a baseband processor, and/or a neural network processor (neural-network processing unit, NPU), etc. Wherein the different processing units may be separate devices or may be integrated in one or more processors.

The controller may be a neural center and a command center of the terminal device 100. The controller can generate operation control signals according to the instruction operation codes and the time sequence signals to finish the control of instruction fetching and instruction execution.

A memory may also be provided in the processor 110 for storing instructions and data. In some embodiments, the memory in the processor 110 is a cache memory. The memory may hold instructions or data that the processor 110 has just used or recycled. If the processor 110 needs to reuse the instruction or data, it can be called directly from the memory. Repeated accesses are avoided and the latency of the processor 110 is reduced, thereby improving the efficiency of the system.

In some embodiments, the processor 110 may include one or more interfaces. The interfaces may include an integrated circuit (inter-integrated circuit, I2C) interface, an integrated circuit built-in audio (inter-integrated circuit sound, I2S) interface, a pulse code modulation (pulse code modulation, PCM) interface, a universal asynchronous receiver transmitter (universal asynchronous receiver/transmitter, UART) interface, a mobile industry processor interface (mobile industry processor interface, MIPI), a general-purpose input/output (GPIO) interface, a subscriber identity module (subscriber identity module, SIM) interface, and/or a universal serial bus (universal serial bus, USB) interface, among others.

The I2C interface is a bi-directional synchronous serial bus comprising a serial data line (SDA) and a serial clock line (serail clock line, SCL). In some embodiments, the processor 110 may contain multiple sets of I2C buses. The processor 110 may be coupled to the touch sensor 180K, charger, flash, camera 193, etc., respectively, through different I2C bus interfaces. For example: the processor 110 may be coupled to the touch sensor 180K through an I2C interface, so that the processor 110 and the touch sensor 180K communicate through an I2C bus interface to implement a touch function of the terminal device 100.

The I2S interface may be used for audio communication. In some embodiments, the processor 110 may contain multiple sets of I2S buses. The processor 110 may be coupled to the audio module 170 via an I2S bus to enable communication between the processor 110 and the audio module 170. In some embodiments, the audio module 170 may transmit an audio signal to the wireless communication module 160 through the I2S interface, to implement a function of answering a call through the bluetooth headset.

PCM interfaces may also be used for audio communication to sample, quantize and encode analog signals. In some embodiments, the audio module 170 and the wireless communication module 160 may be coupled through a PCM bus interface. In some embodiments, the audio module 170 may also transmit audio signals to the wireless communication module 160 through the PCM interface to implement a function of answering a call through the bluetooth headset. Both the I2S interface and the PCM interface may be used for audio communication.

The UART interface is a universal serial data bus for asynchronous communications. The bus may be a bi-directional communication bus. It converts the data to be transmitted between serial communication and parallel communication. In some embodiments, a UART interface is typically used to connect the processor 110 with the wireless communication module 160. For example: the processor 110 communicates with a bluetooth module in the wireless communication module 160 through a UART interface to implement a bluetooth function. In some embodiments, the audio module 170 may transmit an audio signal to the wireless communication module 160 through a UART interface, to implement a function of playing music through a bluetooth headset.

The MIPI interface may be used to connect the processor 110 to peripheral devices such as a display 194, a camera 193, and the like. The MIPI interfaces include camera serial interfaces (camera serial interface, CSI), display serial interfaces (display serial interface, DSI), and the like. In some embodiments, processor 110 and camera 193 communicate through a CSI interface to implement the photographing function of terminal device 100. The processor 110 and the display 194 communicate via a DSI interface to implement the display function of the terminal device 100.

The GPIO interface may be configured by software. The GPIO interface may be configured as a control signal or as a data signal. In some embodiments, a GPIO interface may be used to connect the processor 110 with the camera 193, the display 194, the wireless communication module 160, the audio module 170, the sensor module 180, and the like. The GPIO interface may also be configured as an I2C interface, an I2S interface, a UART interface, an MIPI interface, etc.

The USB interface 130 is an interface conforming to the USB standard specification, and may specifically be a Mini USB interface, a Micro USB interface, a USB Type C interface, or the like. The USB interface 130 may be used to connect a charger to charge the terminal device 100, or may be used to transfer data between the terminal device 100 and a peripheral device. And can also be used for connecting with a headset, and playing audio through the headset. The interface may also be used to connect other terminal devices, such as AR devices, etc.

It should be understood that the interfacing relationship between the modules illustrated in the embodiment of the present application is only illustrative, and does not constitute a structural limitation of the terminal device 100. In other embodiments of the present application, the terminal device 100 may also use different interfacing manners, or a combination of multiple interfacing manners in the foregoing embodiments.

The charge management module 140 is configured to receive a charge input from a charger. The charger can be a wireless charger or a wired charger. In some wired charging embodiments, the charge management module 140 may receive a charging input of a wired charger through the USB interface 130. In some wireless charging embodiments, the charge management module 140 may receive wireless charging input through a wireless charging coil of the terminal device 100. The charging management module 140 may also supply power to the terminal device through the power management module 141 while charging the battery 142.

The power management module 141 is used for connecting the battery 142, and the charge management module 140 and the processor 110. The power management module 141 receives input from the battery 142 and/or the charge management module 140 and provides power to the processor 110, the internal memory 121, the external memory, the display 194, the camera 193, the wireless communication module 160, and the like. The power management module 141 may also be configured to monitor battery capacity, battery cycle number, battery health (leakage, impedance) and other parameters. In other embodiments, the power management module 141 may also be provided in the processor 110. In other embodiments, the power management module 141 and the charge management module 140 may be disposed in the same device.

The wireless communication function of the terminal device 100 can be implemented by the antenna 1, the antenna 2, the mobile communication module 150, the wireless communication module 160, a modem processor, a baseband processor, and the like.

The antennas 1 and 2 are used for transmitting and receiving electromagnetic wave signals. The structures of the antennas 1 and 2 in fig. 1 are only one example. Each antenna in the terminal device 100 may be used to cover a single or multiple communication bands. Different antennas may also be multiplexed to improve the utilization of the antennas. For example: the antenna 1 may be multiplexed into a diversity antenna of a wireless local area network. In other embodiments, the antenna may be used in conjunction with a tuning switch.

The mobile communication module 150 may provide a solution including 2G/3G/4G/5G wireless communication applied to the terminal device 100. The mobile communication module 150 may include at least one filter, switch, power amplifier, low noise amplifier (low noise amplifier, LNA), etc. The mobile communication module 150 may receive electromagnetic waves from the antenna 1, perform processes such as filtering, amplifying, and the like on the received electromagnetic waves, and transmit the processed electromagnetic waves to the modem processor for demodulation. The mobile communication module 150 can amplify the signal modulated by the modem processor, and convert the signal into electromagnetic waves through the antenna 1 to radiate. In some embodiments, at least some of the functional modules of the mobile communication module 150 may be disposed in the processor 110. In some embodiments, at least some of the functional modules of the mobile communication module 150 may be provided in the same device as at least some of the modules of the processor 110.

The modem processor may include a modulator and a demodulator. The modulator is used for modulating the low-frequency baseband signal to be transmitted into a medium-high frequency signal. The demodulator is used for demodulating the received electromagnetic wave signal into a low-frequency baseband signal. The demodulator then transmits the demodulated low frequency baseband signal to the baseband processor for processing. The low frequency baseband signal is processed by the baseband processor and then transferred to the application processor. The application processor outputs sound signals through an audio device (not limited to the speaker 170A, the receiver 170B, etc.), or displays images or video through the display screen 194. In some embodiments, the modem processor may be a stand-alone device. In other embodiments, the modem processor may be provided in the same device as the mobile communication module 150 or other functional module, independent of the processor 110.

The wireless communication module 160 may provide solutions for wireless communication including wireless local area network (wireless local area networks, WLAN) (e.g., wireless fidelity (wireless fidelity, wi-Fi) network), bluetooth (BT), global navigation satellite system (global navigation satellite system, GNSS), frequency modulation (frequency modulation, FM), near field wireless communication technology (near field communication, NFC), infrared technology (IR), etc., applied on the terminal device 100. The wireless communication module 160 may be one or more devices that integrate at least one communication processing module. The wireless communication module 160 receives electromagnetic waves via the antenna 2, modulates the electromagnetic wave signals, filters the electromagnetic wave signals, and transmits the processed signals to the processor 110. The wireless communication module 160 may also receive a signal to be transmitted from the processor 110, frequency modulate it, amplify it, and convert it to electromagnetic waves for radiation via the antenna 2.

In some embodiments, antenna 1 and mobile communication module 150 of terminal device 100 are coupled, and antenna 2 and wireless communication module 160 are coupled, such that terminal device 100 may communicate with a network and other devices via wireless communication techniques. The wireless communication techniques may include the Global System for Mobile communications (global system for mobile communications, GSM), general packet radio service (general packet radio service, GPRS), code division multiple access (code division multiple access, CDMA), wideband code division multiple access (wideband code division multiple access, WCDMA), time division code division multiple access (time-division code division multiple access, TD-CDMA), long term evolution (long term evolution, LTE), BT, GNSS, WLAN, NFC, FM, and/or IR techniques, among others. The GNSS may include a global satellite positioning system (global positioning system, GPS), a global navigation satellite system (global navigation satellite system, GLONASS), a beidou satellite navigation system (Beidou navigation satellite system, BDS), a quasi zenith satellite system (quasi-zenith satellite system, QZSS) and/or a satellite based augmentation system (satellite based augmentation systems, SBAS).

The terminal device 100 implements display functions through a GPU, a display screen 194, an application processor, and the like. The GPU is a microprocessor for image processing, and is connected to the display 194 and the application processor. The GPU is used to perform mathematical and geometric calculations for graphics rendering. Processor 110 may include one or more GPUs that execute program instructions to generate or change display information.

The display screen 194 is used to display images, videos, and the like. The display 194 includes a display panel. The display panel may employ a liquid crystal display (liquid crystal display, LCD), an organic light-emitting diode (OLED), an active-matrix organic light-emitting diode (AMOLED) or an active-matrix organic light-emitting diode (matrix organic light emitting diode), a flexible light-emitting diode (flex), a mini, a Micro led, a Micro-OLED, a quantum dot light-emitting diode (quantum dot light emitting diodes, QLED), or the like. In some embodiments, the terminal device 100 may include 1 or N display screens 194, N being a positive integer greater than 1.

The terminal device 100 may implement a photographing function through an ISP, a camera 193, a video codec, a GPU, a display screen 194, an application processor, and the like.

The ISP is used to process data fed back by the camera 193. For example, when photographing, the shutter is opened, light is transmitted to the camera photosensitive element through the lens, the optical signal is converted into an electric signal, and the camera photosensitive element transmits the electric signal to the ISP for processing and is converted into an image visible to naked eyes. ISP can also optimize the noise, brightness and skin color of the image. The ISP can also optimize parameters such as exposure, color temperature and the like of a shooting scene. In some embodiments, the ISP may be provided in the camera 193.

The camera 193 is used to capture still images or video. The object generates an optical image through the lens and projects the optical image onto the photosensitive element. The photosensitive element may be a charge coupled device (charge coupled device, CCD) or a Complementary Metal Oxide Semiconductor (CMOS) phototransistor. The photosensitive element converts the optical signal into an electrical signal, which is then transferred to the ISP to be converted into a digital image signal. The ISP outputs the digital image signal to the DSP for processing. The DSP converts the digital image signal into an image signal in a standard RGB, YUV, or the like format. In some embodiments, the terminal device 100 may include 1 or N cameras 193, N being a positive integer greater than 1.

The digital signal processor is used for processing digital signals, and can process other digital signals besides digital image signals. For example, when the terminal device 100 selects a frequency bin, the digital signal processor is used to fourier transform the frequency bin energy, or the like.

Video codecs are used to compress or decompress digital video. The terminal device 100 may support one or more video codecs. In this way, the terminal device 100 can play or record video in various encoding formats, for example: dynamic picture experts group (moving picture experts group, MPEG) 1, MPEG2, MPEG3, MPEG4, etc.

The NPU is a neural-network (NN) computing processor, and can rapidly process input information by referencing a biological neural network structure, for example, referencing a transmission mode between human brain neurons, and can also continuously perform self-learning. Applications such as intelligent awareness of the terminal device 100 may be implemented by the NPU, for example: image recognition, face recognition, speech recognition, text understanding, etc.

The external memory interface 120 may be used to connect an external memory card, such as a Micro SD card, to realize expansion of the memory capability of the terminal device 100. The external memory card communicates with the processor 110 through an external memory interface 120 to implement data storage functions. For example, files such as music, video, etc. are stored in an external memory card.

The internal memory 121 may be used to store computer executable program code including instructions. The processor 110 executes various functional applications of the terminal device 100 and data processing by executing instructions stored in the internal memory 121. The internal memory 121 may include a storage program area and a storage data area. The storage program area may store an application program (such as a sound playing function, an image playing function, etc.) required for at least one function of the operating system, etc. The storage data area may store data (such as audio data, phonebook, etc.) created during use of the terminal device 100, and the like. In addition, the internal memory 121 may include a high-speed random access memory, and may further include a nonvolatile memory such as at least one magnetic disk storage device, a flash memory device, a universal flash memory (universal flash storage, UFS), and the like.

The terminal device 100 may implement audio functions through an audio module 170, a speaker 170A, a receiver 170B, a microphone 170C, an earphone interface 170D, an application processor, and the like. Such as music playing, recording, etc.

The audio module 170 is used to convert digital audio information into an analog audio signal output and also to convert an analog audio input into a digital audio signal. The audio module 170 may also be used to encode and decode audio signals. In some embodiments, the audio module 170 may be disposed in the processor 110, or a portion of the functional modules of the audio module 170 may be disposed in the processor 110.

The speaker 170A, also referred to as a "horn," is used to convert audio electrical signals into sound signals. The terminal device 100 can listen to music or to handsfree talk through the speaker 170A.

A receiver 170B, also referred to as a "earpiece", is used to convert the audio electrical signal into a sound signal. When the terminal device 100 receives a call or voice message, it is possible to receive voice by approaching the receiver 170B to the human ear.

Microphone 170C, also referred to as a "microphone" or "microphone", is used to convert sound signals into electrical signals. When making a call or transmitting voice information, the user can sound near the microphone 170C through the mouth, inputting a sound signal to the microphone 170C. The terminal device 100 may be provided with at least one microphone 170C. In other embodiments, the terminal device 100 may be provided with two microphones 170C, and may implement a noise reduction function in addition to collecting sound signals. In other embodiments, the terminal device 100 may be further provided with three, four or more microphones 170C to collect sound signals, reduce noise, identify the source of sound, implement directional recording functions, etc.

The earphone interface 170D is used to connect a wired earphone. The earphone interface 170D may be a USB interface 130 or a 3.5mm open mobile terminal platform (open mobile terminal platform, OMTP) standard interface, a american cellular telecommunications industry association (cellular telecommunications industry association of the USA, CTIA) standard interface.

The pressure sensor 180A is used to sense a pressure signal, and may convert the pressure signal into an electrical signal. In some embodiments, the pressure sensor 180A may be disposed on the display screen 194. The pressure sensor 180A is of various types, such as a resistive pressure sensor, an inductive pressure sensor, a capacitive pressure sensor, and the like. The capacitive pressure sensor may be a capacitive pressure sensor comprising at least two parallel plates with conductive material. The capacitance between the electrodes changes when a force is applied to the pressure sensor 180A. The terminal device 100 determines the intensity of the pressure according to the change of the capacitance. When a touch operation is applied to the display 194, the terminal device 100 detects the intensity of the touch operation according to the pressure sensor 180A. The terminal device 100 may also calculate the position of the touch from the detection signal of the pressure sensor 180A. In some embodiments, touch operations that act on the same touch location, but at different touch operation strengths, may correspond to different operation instructions. For example: and executing an instruction for checking the short message when the touch operation with the touch operation intensity smaller than the first pressure threshold acts on the short message application icon. And executing an instruction for newly creating the short message when the touch operation with the touch operation intensity being greater than or equal to the first pressure threshold acts on the short message application icon.

The gyro sensor 180B may be used to determine a motion gesture of the terminal device 100. In some embodiments, the angular velocity of the terminal device 100 about three axes (i.e., x, y, and z axes) may be determined by the gyro sensor 180B. The gyro sensor 180B may be used for photographing anti-shake. Illustratively, when the shutter is pressed, the gyro sensor 180B detects the angle of the shake of the terminal device 100, calculates the distance to be compensated by the lens module according to the angle, and allows the lens to counteract the shake of the terminal device 100 by the reverse motion, thereby realizing anti-shake. The gyro sensor 180B may also be used for navigating, somatosensory game scenes.

The air pressure sensor 180C is used to measure air pressure. In some embodiments, the terminal device 100 calculates altitude from barometric pressure values measured by the barometric pressure sensor 180C, aiding in positioning and navigation.

The magnetic sensor 180D includes a hall sensor. The terminal device 100 can detect the opening and closing of the flip cover using the magnetic sensor 180D. In some embodiments, when the terminal device 100 is a folder, the terminal device 100 may detect opening and closing of the folder according to the magnetic sensor 180D. And then according to the detected opening and closing state of the leather sheath or the opening and closing state of the flip, the characteristics of automatic unlocking of the flip and the like are set.

The acceleration sensor 180E can detect the magnitude of acceleration of the terminal device 100 in various directions (typically three axes). The magnitude and direction of gravity may be detected when the terminal device 100 is stationary. The method can also be used for identifying the gesture of the terminal equipment, and is applied to the applications such as horizontal and vertical screen switching, pedometers and the like.

A distance sensor 180F for measuring a distance. The terminal device 100 may measure the distance by infrared or laser. In some embodiments, the terminal device 100 may range using the distance sensor 180F to achieve fast focusing.

The proximity light sensor 180G may include, for example, a Light Emitting Diode (LED) and a light detector, such as a photodiode. The light emitting diode may be an infrared light emitting diode. The terminal device 100 emits infrared light outward through the light emitting diode. The terminal device 100 detects infrared reflected light from a nearby object using a photodiode. When sufficient reflected light is detected, it can be determined that there is an object in the vicinity of the terminal device 100. When insufficient reflected light is detected, the terminal device 100 may determine that there is no object in the vicinity of the terminal device 100. The terminal device 100 can detect that the user holds the terminal device 100 close to the ear to talk by using the proximity light sensor 180G, so as to automatically extinguish the screen for the purpose of saving power. The proximity light sensor 180G may also be used in holster mode, pocket mode to automatically unlock and lock the screen.

The ambient light sensor 180L is used to sense ambient light level. The terminal device 100 may adaptively adjust the brightness of the display 194 based on the perceived ambient light level. The ambient light sensor 180L may also be used to automatically adjust white balance when taking a photograph. The ambient light sensor 180L may also cooperate with the proximity light sensor 180G to detect whether the terminal device 100 is in a pocket to prevent false touches.

The fingerprint sensor 180H is used to collect a fingerprint. The terminal device 100 can utilize the collected fingerprint characteristics to realize fingerprint unlocking, access an application lock, fingerprint photographing, fingerprint incoming call answering and the like.

The temperature sensor 180J is for detecting temperature. In some embodiments, the terminal device 100 performs a temperature processing strategy using the temperature detected by the temperature sensor 180J. For example, when the temperature reported by the temperature sensor 180J exceeds a threshold, the terminal device 100 performs a reduction in the performance of a processor located near the temperature sensor 180J in order to reduce power consumption to implement thermal protection. In other embodiments, when the temperature is below another threshold, the terminal device 100 heats the battery 142 to avoid the low temperature causing the terminal device 100 to shut down abnormally. In other embodiments, when the temperature is below a further threshold, the terminal device 100 performs boosting of the output voltage of the battery 142 to avoid abnormal shutdown caused by low temperatures.

The touch sensor 180K, also referred to as a "touch panel". The touch sensor 180K may be disposed on the display screen 194, and the touch sensor 180K and the display screen 194 form a touch screen, which is also called a "touch screen". The touch sensor 180K is for detecting a touch operation acting thereon or thereabout. The touch sensor may communicate the detected touch operation to the application processor to determine the touch event type. Visual output related to touch operations may be provided through the display 194. In other embodiments, the touch sensor 180K may also be disposed on the surface of the terminal device 100 at a different location than the display 194.

The bone conduction sensor 180M may acquire a vibration signal. In some embodiments, bone conduction sensor 180M may acquire a vibration signal of a human vocal tract vibrating bone pieces. The bone conduction sensor 180M may also contact the pulse of the human body to receive the blood pressure pulsation signal. In some embodiments, bone conduction sensor 180M may also be provided in a headset, in combination with an osteoinductive headset. The audio module 170 may analyze the voice signal based on the vibration signal of the sound portion vibration bone block obtained by the bone conduction sensor 180M, so as to implement a voice function. The application processor may analyze the heart rate information based on the blood pressure beat signal acquired by the bone conduction sensor 180M, so as to implement a heart rate detection function.

The keys 190 include a power-on key, a volume key, etc. The keys 190 may be mechanical keys. Or may be a touch key. The terminal device 100 may receive key inputs, generating key signal inputs related to user settings and function controls of the terminal device 100.

The motor 191 may generate a vibration cue. The motor 191 may be used for incoming call vibration alerting as well as for touch vibration feedback. For example, touch operations acting on different applications (e.g., photographing, audio playing, etc.) may correspond to different vibration feedback effects. The motor 191 may also correspond to different vibration feedback effects by touching different areas of the display screen 194. Different application scenarios (such as time reminding, receiving information, alarm clock, game, etc.) can also correspond to different vibration feedback effects. The touch vibration feedback effect may also support customization.

The indicator 192 may be an indicator light, may be used to indicate a state of charge, a change in charge, a message indicating a missed call, a notification, etc.

The SIM card interface 195 is used to connect a SIM card. The SIM card may be contacted and separated from the terminal apparatus 100 by being inserted into the SIM card interface 195 or by being withdrawn from the SIM card interface 195. The terminal device 100 may support 1 or N SIM card interfaces, N being a positive integer greater than 1. The SIM card interface 195 may support Nano SIM cards, micro SIM cards, and the like. The same SIM card interface 195 may be used to insert multiple cards simultaneously. The types of the plurality of cards may be the same or different. The SIM card interface 195 may also be compatible with different types of SIM cards. The SIM card interface 195 may also be compatible with external memory cards. The terminal device 100 interacts with the network through the SIM card to realize functions such as call and data communication. In some embodiments, the terminal device 100 employs esims, namely: an embedded SIM card. The eSIM card can be embedded in the terminal device 100 and cannot be separated from the terminal device 100.

The software system of the terminal device 100 may employ a layered architecture, an event driven architecture, a micro-core architecture, a micro-service architecture, or a cloud architecture. In the embodiment of the application, taking an Android system with a layered architecture as an example, a software structure of the terminal device 100 is illustrated.

Fig. 2 is a software configuration block diagram of the terminal device 100 of the embodiment of the present application. The layered architecture divides the software into several layers, each with distinct roles and branches. The layers communicate with each other through a software interface. In some embodiments, the Android system is divided into four layers, from top to bottom, an application layer, an application framework layer, an Zhuoyun row (Android run) and system libraries, and a kernel layer, respectively. The application layer may include a series of application packages.

As shown in fig. 2, the application package may include applications for cameras, gallery, calendar, phone calls, maps, navigation, WLAN, bluetooth, music, video, short messages, etc.

The application framework layer provides an application programming interface (application programming interface, API) and programming framework for application programs of the application layer. The application framework layer includes a number of predefined functions.

As shown in FIG. 2, the application framework layer may include a window manager, a content provider, a view system, a telephony manager, a resource manager, a notification manager, and the like.

The window manager is used for managing window programs. The window manager can acquire the size of the display screen, judge whether a status bar exists, lock the screen, intercept the screen and the like.

The content provider is used to store and retrieve data and make such data accessible to applications. The data may include video, images, audio, calls made and received, browsing history and bookmarks, phonebooks, etc.

The view system includes visual controls, such as controls to display text, controls to display pictures, and the like. The view system may be used to build applications. The display interface may be composed of one or more views. For example, a display interface including a text message notification icon may include a view displaying text and a view displaying a picture.

The telephony manager is used to provide the communication functions of the terminal device 100. Such as the management of call status (including on, hung-up, etc.).

The resource manager provides various resources for the application program, such as localization strings, icons, pictures, layout files, video files, and the like.

The notification manager allows the application to display notification information in a status bar, can be used to communicate notification type messages, can automatically disappear after a short dwell, and does not require user interaction. Such as notification manager is used to inform that the download is complete, message alerts, etc. The notification manager may also be a notification in the form of a chart or scroll bar text that appears on the system top status bar, such as a notification of a background running application, or a notification that appears on the screen in the form of a dialog window. For example, a text message is prompted in a status bar, a prompt tone is emitted, the terminal equipment vibrates, and an indicator light blinks.

Android runtimes include core libraries and virtual machines. Android run time is responsible for scheduling and management of the Android system.

The core library consists of two parts: one part is a function which needs to be called by java language, and the other part is a core library of android.

The application layer and the application framework layer run in a virtual machine. The virtual machine executes java files of the application program layer and the application program framework layer as binary files. The virtual machine is used for executing the functions of object life cycle management, stack management, thread management, security and exception management, garbage collection and the like.

The system library may include a plurality of functional modules. For example: surface manager (surface manager), media library (media library), three-dimensional graphics processing library (e.g., openGL ES), 2D graphics engine (e.g., SGL), etc.

The surface manager is used to manage the display subsystem and provides a fusion of 2D and 3D layers for multiple applications.

Media libraries support a variety of commonly used audio, video format playback and recording, still image files, and the like. The media library may support a variety of audio and video encoding formats, such as MPEG4, h.264, MP3, AAC, AMR, JPG, PNG, etc.

The three-dimensional graphic processing library is used for realizing three-dimensional graphic drawing, image rendering, synthesis, layer processing and the like.

The 2D graphics engine is a drawing engine for 2D drawing.

The kernel layer is a layer between hardware and software. The inner core layer at least comprises a display driver, a camera driver, an audio driver and a sensor driver.

In order to facilitate understanding of the technical solution of the present application, the following terms are first explained.

DBV: the display luminance level, also referred to as display luminance value (display brightness value, DBV), is referred to herein as luminance level.

2. Gray scale value: the value range is usually 0-255, which is a numerical value representing the brightness of the pixel point. The higher the gray-scale value, the higher the luminance, the lower the gray-scale value, and the lower the luminance.

Pwm mode: a pulse width modulation (pulse width modulation) mode, which is one of dimming modes of a display device, is generally a PWM mode in the case of a relatively low brightness level;

dc mode: the direct current mode (direct current mode), which is also one of the display device dimming modes, typically employs a DC mode when the brightness level is relatively high.

According to the technical scheme, when a fingerprint light spot is excited, the DDIC obtains a target gray-scale mapping coefficient corresponding to the initial brightness level entering the reference brightness level, determines a new gray-scale value which enables the brightness of a background picture to be unchanged or changed little under the reference brightness level according to the target gray-scale mapping coefficient and the initial gray-scale value, and then displays the background picture under the reference brightness level by adopting the new gray-scale value, so that the brightness mutation of the background picture during light spot excitation is avoided. In the method, although the brightness level is changed, a screen is not required to be switched to a new frame rate, a set of registers are not required to be occupied to store brightness parameters corresponding to the new frame rate, and the registers are not required to be added, so that the cost is prevented from increasing.

In order to implement the technical solution of the present application, on the basis of the general architecture shown in fig. 2, the software architecture of the terminal device may also be shown in fig. 3, where a Touch Panel (TP) and a DDIC are provided in a Hardware layer (Hardware). When a user touches a touch TP, a touch screen driving module (TP Driver) in a driving layer (Driver layer) can recognize a touch instruction, then the touch instruction is notified to a fingerprint driving module (Finger Print Driver, FP river) in the Driver layer, and the instruction is transmitted to an FP Hal module of a hardware abstraction layer (Hardware Abstract Layer, hal) by the FP river. The FP Hal module in turn transmits instructions to a display driver module (LCD river) of the driver layer, which excites the fingerprint spots.

It should be noted that, in general, the display device will switch the frame rate according to the usage requirement, and different brightness parameters will be called for at different frame rates to ensure the consistency of the display effect. Therefore, the DDIC can also receive the brightness parameter corresponding to the current frame rate, namely the brightness level and the corresponding gray scale value, issued by the upper layer while the frame rate of the display device is switched. When the DDIC displays according to the received brightness parameter, the brightness of the screen display can be controlled. Each frame rate corresponds to a set of brightness parameters, each set of brightness parameters can be stored in a corresponding register, and the brightness parameters are parameters obtained by gamma debugging of a screen. Typically, several sets of registers of different frame rates are built into the DDIC to store corresponding brightness parameters, e.g., a set of 60Hz, a set of 90Hz, and a set of 120 Hz. Under the action of the brightness parameters stored in the registers, stable brightness display can be ensured even if the screen is converted into different frame rates for the same display picture, and brightness jump can not occur. Thus, the FP Hal module may also notify the fingerprint Service module (FP Service) at the application Framework layer (Framework layer) on the basis of the above procedure, and pass through the FP Service to the accelerated graphics port Service module (Accelerate Graphical Port Service, AGP Service) at the system library (Native layer). Optionally, the AGP service may switch the frame rate to a high frame rate as needed, entering a local high brightness mode (local high brightness mode, LHBM); the frame rate may be switched to another frame rate as needed, and the frame rate of the display device is not limited in the present application. And then, an instruction for switching the frame rate (frame cutting) is issued to the LCD Driver through an SF module and a HWC module of the Hal layer, namely, the LCD Driver is informed to display according to the new frame rate. However, in the technical scheme of the application, the frame cutting process is not forced, and the instruction for exciting the fingerprint light spot is transmitted to the LCD river through the FP Hal, so that the brightness control can be realized, the frame cutting is not forced, the brightness adjustment of the screen can be realized, and the flow of unlocking the fingerprint and lighting the light spot is further simplified. Meanwhile, under the condition that the frame cutting process is not required to be carried out forcedly, the problem that the frame rate of an upper layer is not matched with the frame rate of a lower layer due to the fact that the frame rate of the DDIC is switched in time when the DDIC cuts frames in a traditional mode can be avoided.

The execution body of the embodiment of the present application may be a processor, a chip, or a terminal device, and hereinafter, an exemplary description will be made with the execution body as a DDIC.

Fig. 4 is a flowchart illustrating an exemplary method for determining a gray level according to an embodiment of the present application. The method comprises the following steps:

s401, acquiring an initial gray scale value of the display device under an initial brightness level, wherein the initial brightness level is used for representing the brightness level of the display device in the current display state, and the initial gray scale value is used for representing the brightness of the display device under the initial brightness level.

It should be noted that the display panel of the display device has an adjustment range of DBV, and the brightness level of the display device (including the screen, the touch screen, etc. referred to herein) can be changed within the adjustment range. In an ideal case, the gamma value of the gamma curve corresponding to each brightness level in the adjustment range of the display brightness level corresponds to the target value, for example, approximately 2.2. Thus, at each brightness level, the display device presents a display effect that corresponds to the visual perception of the human eye.

Then in the bright screen state, the display device displays the background picture according to the initial brightness level of the current state and the initial gray scale value of the initial brightness level. The background picture refers to a picture displayed when the bright screen is not unlocked, and does not contain fingerprint light spots.

Specifically, the DDIC may read an initial brightness level, i.e., an initial DBV, at which the display device is in a current display state. The DDIC may also read an initial gray-scale value of the display device at an initial brightness level.

S402, when the fingerprint light spots are excited, a target gray-scale mapping coefficient and a reference brightness level are obtained, wherein the target gray-scale mapping coefficient is a coefficient corresponding to the display device when the initial brightness level is switched to the reference brightness level.

Note that the dimming mode of the display device includes a PWM mode and a DC mode. The PWM mode is a mode in which the light emission efficiency is always at the highest state by changing the light emission time of the display panel of the display device on the basis of changing the output pulse width, thereby changing the brightness. While DC mode is capable of automatically adjusting the brightness of a display device in the event that the current ambient brightness is perceived, the brightness is changed by increasing or decreasing the power of the display device.

When the display device is in a bright screen state, for example, the display device is shown as a diagram a in fig. 5, the display device can display fingerprint spots besides a background picture, a user needs to press the fingerprint spots to unlock, namely, the operation is shown as a diagram b in fig. 5, and at this time, the under-screen camera can acquire images of fingerprints.

However, in a typical display device, for example, when a touch screen is used to capture a fingerprint covered on the touch screen, if the touch screen is in PWM mode, a black bar is likely to appear, which affects the recognition of the fingerprint and thus the unlocking rate. For fingerprint identification, the unlocking rate needs to be guaranteed when the fingerprint light spot is lightened and the display device is in a high-brightness state, namely the dimming mode of the touch screen needs to be in a DC mode. Thus, when the fingerprint spot is excited, the dimming mode needs to go from PWM mode to DC mode. If the brightness level of the display device is relatively low when displaying the background picture before the fingerprint flare is excited, the brightness level of the display device is changed from low to high. For example, the previous brightness level is DBV800, then after the fingerprint spot is excited, the brightness level will enter the high brightness level corresponding to DC mode, for example, DBV1102, due to the excitation of the spot. If the DDIC displays the background picture in the original gray level value of the DBV800, the background picture suddenly becomes bright.

Specifically, the DDIC receives a target gray-scale mapping coefficient and a reference brightness level issued by the terminal device; the target gray-scale mapping coefficient and the reference brightness level issued by a System On Chip (SOC) on the terminal device where the DDIC is located may also be used.

The target gradation mapping coefficient and the reference luminance level will be described first. Taking the SOC issuing the target gray-scale mapping coefficient as an example, when the fingerprint light spot is excited, the SOC may find a preset mapping relationship according to the initial brightness level. The mapping relationship may include a set of mapping relationships corresponding to the reference brightness levels, where the mapping relationships include a plurality of brightness levels and a plurality of gray-scale mapping coefficients. The correspondence may be one-to-one correspondence, or one-to-many or many-to-one correspondence, and is not limited thereto. The reference brightness level may be a higher brightness level in the adjustment range of the brightness level of the display device, for example, a maximum value in the adjustment range or a corresponding brightness level in the DC mode, which is not limited in the embodiment of the present application.

The mapping relation is described here: the mapping relationship may include a correspondence relationship between a plurality of luminance levels and a plurality of gray-scale mapping coefficients at a reference luminance level, for example, the correspondence relationship between a plurality of luminance levels and a plurality of gray-scale mapping coefficients at a DBV1102 where the reference luminance level is fixed, which may be specifically shown in table 1. The correspondence relationship indicates that if the display apparatus is to enter the reference luminance level, different luminance levels each correspond to a plurality of gradation mapping coefficients. In table 1, each of the different brightness levels may correspond to a different gray-scale mapping coefficient, or may be adjacent gray-scale mapping coefficients with the same brightness level, which is not limited in the embodiment of the present application, and specific coefficients may correspond to each other according to the debugging or simulation result. The DBV values in Table 1 represent different luminance levels, table base represents a reference luminance level, and Ratio values represent gray-scale mapping coefficients, which may also be referred to as mask coefficients, and the values in Table 1 are shown in 16 scale. Where 44E represents decimal 1102. It should be noted that the Ratio value itself characterizes the coefficients between 0 and 1, and the expression of the Ratio value in table 1 is: the first bit represents an enable bit, and an enable bit of "1" indicates that the Ratio value is in an enabled state for calculation of luminance. The second through fourth bits of the Ratio value in table 1 represent the magnitude of the value. Since the registers cannot directly store the decimal numbers, taking the register corresponding to the Ratio value as an example of 12 bits in table 1, the maximum value (12 bits are all 1) stored in the 12 bits, that is, 4095 in decimal, corresponds to 1 as the maximum value of the Ratio value, and 4095 in decimal corresponds to "FFF" in 16. Thus, the maximum Ratio value in table 1 is denoted as "1FFF". For example, with continued reference to Ratio value "1305" in table 1, hexadecimal 305 corresponds to decimal 773, and when 773 is divided by 4095 (equal), then the actual Ratio value corresponding to the DBV may be represented.

TABLE 1

DBV value	Table base	Ratio value
			0	44E	1000
1	44E	12F6
			2	44E	12F6
3	44E	12F7
			4	44E	12F8
5	44E	12F9
			6	44E	12FA
7	44E	12FC
			8	44E	12FD
9	44E	12FE
			A	44E	12FF
B	44E	1300
			C	44E	1302
D	44E	1305
			...	...	...
44D	44E	1FFC
			44E	44E	1FFF

Alternatively, the mapping relationship may also include a plurality of reference brightness levels, and each reference brightness level includes a corresponding relationship between a plurality of brightness levels and a plurality of gray-scale mapping coefficients, and the corresponding relationship between each reference brightness level may be different. That is, the mapping relationship may include the correspondence between the plurality of brightness levels and the plurality of gray-scale mapping coefficients corresponding to each Table base under a plurality of different Table bases. For example, the Table base 44E mapping relationship may include the correspondence relationship in Table 1 above; the mapping relation of the Table base being FA0 may also include a correspondence relation between a brightness level and a plurality of gray-scale mapping coefficients, and the application is not limited to the number and specific values of a plurality of different Table bases. The correspondence between the plurality of luminance levels and the plurality of gray-scale mapping coefficients under the Table base other than the DBV44E may be added on the basis of the above Table 1, that is, the correspondence between the plurality of luminance levels, at least one reference luminance level, and the plurality of gray-scale mapping coefficients may be included in the mapping relationship. When different reference brightness levels need to be entered, namely, when corresponding relations under different Table base need to be selected, the mapping relations can be directly searched to obtain the needed target gray-scale mapping coefficients.

Optionally, the SOC may search in the mapping relationship according to the reference brightness level and the initial brightness level, find a set of mapping relationship corresponding to the required reference brightness level from the mapping relationship, find a target gray-scale mapping coefficient corresponding to the initial brightness level from the set of mapping relationship, and issue the target gray-scale mapping coefficient to the DDIC. It should be noted that, each group of mapping relationships corresponds to a reference brightness level, and mapping relationships of different groups can be selected according to different invoked reference brightness levels. Specifically, the DDIC may receive a target grayscale mapping coefficient issued by the SOC.

Alternatively, the mapping relationship may be obtained experimentally, or may be obtained through simulation or calculation.

S403, determining a target gray scale value according to the target gray scale mapping coefficient and the initial gray scale value. The difference between the brightness of the initial gray scale value under the initial brightness level and the brightness of the target gray scale value under the reference brightness level is smaller than a preset threshold value. The display device is used for displaying a background picture according to the target gray scale value under the reference brightness level.

Specifically, the DDIC may redetermine a new target gray-scale value at the reference brightness level according to the target gray-scale mapping coefficient and the initial gray-scale value.

For example, DDIC may calculate a target gray-scale value according to the following formula (1) or a variation of the formula.

In the above formula (1), brightness ₈₀₀ And Brightness ₁₁₀₂ Representing the brightness of the same gray scale value characterized by different brightness levels, wherein the unit is nit. Brightness of ₈₀₀ Can represent the Brightness represented by the initial gray-scale value at the initial Brightness level, the Brightness ₈₀₀ Take the initial brightness level DBV800 as an example; brightness of ₁₁₀₂ Representing the initial ashThe Brightness represented by the step value at the reference Brightness level, the Brightness ₁₁₀₂ A reference brightness level DBV1102 is exemplified. Where γ is a gamma coefficient, the value of the gamma coefficient is related to the hardware characteristic of the display device, for example, the gamma coefficient of a common display device is 2.2.

The respective Ratio values in the above table 1 also satisfy the above formula (1). For example, brightness ₈₀₀ When the brightness level is DBV800, the brightness 30nit, brightness corresponding to the gray level value of L255 ₁₁₀₂ For brightness 90nit corresponding to the gray level of L255 with the brightness level of DBV1102, the Ratio value is

When the Ratio value is found by the initial brightness level and the found Ratio value is used to determine the gray-scale value under the new DBV, the relationship of the above formula (1) is also satisfied. In a specific calculation process, the above formula (1) may be rewritten as the formula (2) or a modification of the formula.

Brightness ₈₀₀ ＝Brightness ₁₁₀₂ ×(Ratio) ^γ Formula (2)

The target gray-scale value at the reference luminance level is determined using the above formula (2) or a variation of the formula (2). For example, knowing that L255 has a Brightness of 90nit under DBV1102, the Ratio value and Brightness to be found ₁₁₀₂ For 90nit, take into equation (2) to find Brightness ₈₀₀ 0.6096 of a shape of 0.6096 ^2.2 The x 90nit is about 30nit, and then searches the gamma curve corresponding to the DBV1102, for example, searches the lower curve in the b graph in fig. 10, and the gray level corresponding to 30nit is known to be L150, that is, when the new DBV is 1102 and the brightness of 30nit needs to be displayed, the target gray level is known to be L150.

It should be noted that, in the above mapping relationship, the luminance of the initial gray-scale value at the initial luminance level and the luminance of the target gray-scale value at the reference luminance level are the same or similar, that is, the difference between the luminance in the two states is smaller than a preset threshold, where the preset threshold may be a smaller value such as 1nit, 1.5nit, or 2 nit. For example, the initial gray-scale value L255 at the initial luminance level DBV800 is mapped by the corresponding gray-scale mapping coefficient, and then the target gray-scale value corresponding to the reference luminance level DBV1102 is L150. That is, if the initial gray-scale value L255 under the DBV800 shows a luminance of 30nit, the target gray-scale value L150 under the DBV1102 also shows a luminance of 30nit. Alternatively, the brightness corresponding to the target gray-scale value of the DBV1102 determined by the DDIC being other values may be a brightness having a difference from 30nit smaller than a preset threshold, for example, 29nit, 31nit, etc., and a gray-scale value closest to 30nit may be generally selected as the target gray-scale value.

In addition, the number of gray-scale values corresponding to the number of nits at the same brightness level is also determined in advance after being tested and debugged, and stored in a register, for example, a gamma curve shown by DBV800 and DBV1102 shown in fig. 10 as a general b diagram, wherein the gray-scale value L255 at BDV800 corresponds to the brightness of 30 nits.

When the display device displays the brightness of the background picture according to the target gray scale value at the reference brightness level, the brightness of the background picture displayed by the display device according to the initial gray scale value at the initial brightness level is the same or similar, and no brightness abrupt change occurs. For example, if the initial gray-scale value L255 (where L represents luminance) of the DBV800 shows a luminance of 30nit, the target gray-scale value L150 of the DBV1102 also shows a luminance of 30nit, which can be expressed by the expression L255800 =l 1501102.

In the embodiment shown in fig. 4, the DDIC obtains the target gray-scale mapping coefficient and the reference brightness level when exciting the fingerprint light spot, and determines the target gray-scale value required under the reference brightness level according to the target gray-scale mapping coefficient and the initial gray-scale value. Because the difference between the brightness presented by the target gray scale value under the reference brightness level and the brightness presented by the initial gray scale value under the initial brightness level is smaller than the preset threshold value, the display device can display the background picture according to the target gray scale value under the reference brightness level, the presented brightness is consistent with the brightness of the background picture displayed according to the initial gray scale value under the initial brightness level, and the brightness of the background picture cannot be suddenly changed in the process of exciting the fingerprint facula. When the method enters the excitation fingerprint light spot, even if the method enters the LHBM, the frame rate of the display device in display is not required to be switched, so that a special register is not required to be occupied solely for storing the brightness parameter, and the resource waste of the register is avoided.

In the embodiment of the application, two dynamic parameter interfaces of Table base and Ratio can be opened, so that the reference brightness level and the gray level mapping coefficient can be dynamically obtained, when the method is applied to different products, the debugging can be flexibly carried out, and only the mapping relation is required to be adjusted, so that the method has the advantages of flexibility, convenience in updating and debugging new projects and wider application scene.

Optionally, if the terminal device recalculates the folded gray scale value of the background picture when entering the DC mode through the SOC, the SOC is required to redraw the background picture according to the folded gray scale value to generate a new background picture, which consumes a long time and affects the user experience. According to the technical scheme, the DDIC can determine the new target gray level value according to the target gray level mapping coefficient issued by the SOC and the initial gray level value, and the DDIC can display the background picture directly according to the target gray level value, so that the SOC does not need to recalculate the resources of the background picture, response time is saved, and user experience is improved.

In some embodiments, the reference brightness level may be selected to be a fixed value, i.e. when the fingerprint spot is activated, the display device enters a fixed DBV. This fixed DBV may select the highest brightness level, which may correspond to the brightest state of the display device. In the embodiment of the present application, the range between DBV0 and the reference brightness level is called an alpha interval. Fig. 6 is a schematic diagram of an alpha interval when the reference brightness level is the highest brightness level DBV 4000.

The following describes the technical solution of the present application, taking the highest brightness level as DBV4000 and the brightest brightness as 1000nit as an example: that is, when a spot is excited, the display device is directly switched to the brightness level of the DBV 4000. At this time, the SOC may only need to query the mapping relationship in table 1, determine the target gray-scale mapping coefficient corresponding to the initial brightness level under the DBV4000 from the mapping relationship, and issue the DBV4000 and the target gray-scale mapping coefficient to the DDIC, where the DDIC determines a new target gray-scale value according to the target gray-scale mapping coefficient and the initial gray-scale value. The fixed DBV is adopted as the reference brightness level, so that not only can the brightness abrupt change of the background picture when the fingerprint light spot is excited be avoided, but also the frame rate when the display device is switched is not required, and therefore, a special register is not required to be occupied solely for storing brightness parameters, and the resource waste of the register is avoided.

When the fixed high brightness level is used as the reference brightness level when the fingerprint light spots are excited, the brightness of the excited light spots at different frame rates fluctuates. The graph a in fig. 7 shows the brightness change (Δl/L) of the fingerprint spot excited at various frame rates, i.e., the brightness (L, nit) change rate, which is about 5%. At this time, the brightness of the fingerprint light spot under different DBVs is relatively stable, the brightness curve can be seen from the b diagram in fig. 7, the brightness curve always keeps a state close to a straight line, and the unlocking success rate can be ensured.

When the fixed high-brightness DBV is used as the reference brightness level, the voltage when the fingerprint light spot is excited is constant, and the brightness of the fingerprint light spot is also stable. However, since the storage bits of the gray-scale mapping coefficient (Ratio value) are generally correlated with the storage bits of the Ratio value. If the stored bits of the Ratio value are 12 bits (bits), this means that the range of 0-1 of the Ratio value is divided into 4095 levels, i.e. the number of Ratio values is 4096 (12 th power of 2). If 4095-level gray-scale mapping is used to eliminate the adjustment range of the brightness level corresponding to the whole range of the DBV0-DBV4000, the interval of the DBV corresponding to each level of gray-scale mapping coefficient is relatively large, and about one level of Ratio corresponds to one brightness level, so that the brightness difference between gray-scale values under the reference brightness level is relatively large, and the brightness change control is insufficient. Thus, in other embodiments, the fineness of the brightness variation control may be increased by compressing the alpha interval.

Optionally, the α interval is compressed by selecting an intermediate luminance level as the reference luminance level. Alternatively, the brightness level corresponding to the DC mode closest to the PWM mode may be selected, i.e. the brightness level threshold of the dimming mode at the time of switching the PWM mode and the DC mode is selected. For example, when the display device displays a background picture with a luminance of 90nit or more, the dimming mode is DC mode, and the difference in visual effect between the luminance of 90nit or more and the highest luminance is not large in general; when the brightness of the background picture displayed by the display device is less than 90nit (e.g., 2-90 nit), the dimming mode is a PWM mode, and the brightness of 90nit corresponds to the DBV1102, the reference brightness level may be selected as the DBV1102. When the initial brightness level is smaller than the DBV1102, that is, when the brightness in the initial state is smaller than 90nit, the DDIC performs the target gray-scale mapping coefficient and the initial gray-scale value according to the reference brightness level DBV1102, and determines the target gray-scale mapping coefficient, so that the display device displays the background picture. The dimming mode of the display device can be ensured to be in a DC mode when the fingerprint light spots are lightened, the alpha interval is compressed while the fingerprint unlocking rate is ensured, the fineness of brightness change control is improved, brightness jump of background pictures is avoided, and the display effect is improved.

Alternatively, after the α interval is compressed, the display device may directly display an initial gray-scale value at an initial brightness level in an adjustment range of the DBV outside the α interval. For example, when the α interval is DBV0-DBV1102, that is, the α interval corresponds to a luminance below 90nit, if the luminance in the initial state has exceeded 90nit, that is, the initial luminance level is greater than DBV1102, the luminance level at this time may meet the fingerprint unlocking requirement, and the display device may display the background picture directly with an initial luminance level and an initial gray level that are greater than DBV1102 without switching to a higher luminance level. Since the brightness of the initial state exceeds 90nit, the brightness of the excited fingerprint light spot can be accurately unlocked, and the brightness level does not need to be improved any more, so that the initial gray scale value in the initial state is multiplexed. Alternatively, the display device may maintain an initial brightness level and display with an initial gray scale value; or dynamically updating the reference brightness level to the initial brightness level, and simultaneously obtaining a target gray scale value according to the target gray scale mapping coefficient of 1, wherein the obtained target gray scale value is equal to the initial gray scale value, so that the multiplexing of the initial gray scale value is realized.

Note that, when multiplexing the initial gray-scale value, it is not necessary to switch the frame rate, and this process is called Gamma multiplexing (Gamma multiplexing), which corresponds to the luminance parameter stored in the register in which the current frame rate is directly multiplexed. The Gamma multiplexing process does not need to switch the frame rate when the display device is displayed, and does not need to occupy a special register alone to store the brightness parameter, so that the resource waste of the register is avoided.

The brightness level section using Gamma multiplexing is referred to as a Gamma multiplexing section. Fig. 8 is a schematic distribution diagram of an alpha interval and a Gamma multiplexing interval during dynamic adjustment of a reference brightness level. In the alpha interval, the range of 0-1 of the Ratio value is also divided into 4095 levels. If 4095-level gray-scale mapping is used to correspond to the adjustment range of the brightness level of DBV0-DBV1102, the interval Ratio of the DBV corresponding to each level of gray-scale mapping coefficient becomes smaller, and the Ratio of one-third level Ratio corresponds to the brightness level, so that the brightness difference between gray-scale values at the reference brightness level is significantly reduced and the brightness change control fineness is higher compared with the alpha interval of fig. 6.

When the dynamic reference brightness level of the compressed alpha interval is adopted, brightness corresponding to different frame rates in the alpha interval fluctuates, namely, the brightness of the fingerprint flare excited by different initial brightness levels fluctuates. The graph a in fig. 9 shows the brightness variation at various frame rates, the brightness fluctuation is about one percent, and the fluctuation range is obviously reduced. As can be seen from the above description, when the fingerprint flare is excited, the factors affecting the brightness of the background picture include the initial gray level value, the initial brightness level (i.e. initial DBV) and the Ratio value, and the brightness of the fingerprint flare is determined by the parameters characterized by the fixed Gamma curve under the HBM, and is generally not affected by the DBV under the premise of ensuring the DC mode. When the fingerprint light spot is usually lighted, the dimming mode of the display device enters a DC mode, and the brightness of the fingerprint light spot can be more or less affected by the EM duty voltage and the Panel voltage. The Panel voltage may include ELVSS voltage and VGPS, VGMP voltages, among others. To save power consumption, the Panel voltage at different brightness levels is set in a linear region adjacent to the saturation region. Taking ELVSS voltage as an example, if the margin of ELVSS voltage is insufficient to support high brightness in the Gamma multiplexing section, the brightness of the fingerprint light spot may fluctuate. The b graph in fig. 9 shows brightness curves of fingerprint light spots of a plurality of display devices in a Gamma multiplexing interval, and it can be seen that brightness fluctuation of the light spots displayed by different display devices is kept within 1000nit+ -100nit, so as to meet the requirement of fingerprint unlocking.

Specifically, the principle of the above technical solution that combines the compressed alpha interval and the Gamma multiplexing interval can be also shown in fig. 10. Fig. 10 is a schematic diagram of luminance level curves of an alpha interval and a Gamma multiplexing interval. Here, the horizontal axis represents the brightness level (DBV), the vertical axis represents the brightness L (nit), and a curve representing the brightness of L255 at different DBVs is shown. The gray-scale value L255 under the DBV800 may show a luminance of 30nit, and mapped to the DBV1102, the gray-scale value becomes L150, and may also show a luminance of 30 nit. Meanwhile, it can be understood that the gray scale values (L0-L255) corresponding to the luminance of 30nit or less of the DBV800 can be mapped to the gray scale values (L0-L150) corresponding to the luminance of 30nit or less of the DBV1102, and specifically, see the mapping curve shown in the b-diagram of fig. 10.

In summary, the higher the reference luminance level, the larger the luminance fluctuation between the gray-scale values at the reference luminance level, the lower the fineness of the luminance change control, but the better the stability of the luminance of the fingerprint flare. The lower the reference brightness level is, the smaller the brightness fluctuation between the gray scale values under the reference brightness level is, the higher the fineness of brightness change control is, and the brightness change rate is low, so that the better the display effect is, and the stability of the brightness of the fingerprint light spots can also meet the requirements. Therefore, the technical scheme of combining the compressed alpha interval and the Gamma multiplexing interval can balance and give consideration to the display effect and the light spot fluctuation during fingerprint unlocking, and has strong rationality.

Table 2 shows the correspondence between the brightness fluctuation range, the number of erroneous judgment sheets and the erroneous judgment rate of different fingerprint spots obtained by testing the technical scheme of the compressed alpha interval and the Gamma multiplexing interval. As can be seen from table 2, the smaller the fluctuation of the brightness of the fingerprint light spot is, the higher the unlocking rate is. The "FER" in table 2 indicates a misjudgment rate, and the higher the misjudgment rate, the lower the unlocking rate of the fingerprint, and the higher the unlocking rate.

TABLE 2

Fingerprint light spot brightness fluctuation	Sample size	Number of misjudged sheets	FER
				-35％	27749	183	0.66％
-25％	27749	121	0.44％
				0	27749	8	0.03％
+10％	27749	179	0.65％
				+15％	27749	725	2.61％
+20％	27749	1790	6.45％

In order to more clearly express the technical scheme of combining the compressed alpha interval and the Gamma multiplexing interval, the method for determining the gray scale value according to the embodiment of the present application may also refer to a flow shown in fig. 11, which includes:

s1101, exciting fingerprint light spots.

S1102, judging whether the brightness corresponding to the initial brightness level is below 90 nit; if yes, executing S1103A; if not, then S1103B is performed.

S1103A, entering a reference brightness level (such as DBV 1102) corresponding to 90nit, simultaneously obtaining a target gray-scale mapping coefficient, and determining a target gray-scale value by adopting the target gray-scale mapping coefficient and a gray-scale value under the initial brightness level.

S1103B, the initial brightness level is used, the target gray level mapping coefficient is taken as 1, and the initial gray level value is multiplexed.

S1104, exiting the fingerprint light spot.

The implementation principle and technical effect of the embodiment shown in fig. 11 can be referred to the description of the foregoing embodiment, and will not be repeated here.

Examples of the methods provided by the present application are described in detail above. It is to be understood that the corresponding means, in order to carry out the functions described above, comprise corresponding hardware structures and/or software modules for carrying out the respective functions. Those of skill in the art will readily appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is implemented as hardware or computer software driven hardware depends upon the particular application and design constraints imposed on the solution. 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 application.

The present application may divide the function modules of the device for determining the gray-scale value according to the above-described method example, for example, each function may be divided into each function module, or two or more functions may be integrated into one module. The integrated modules may be implemented in hardware or in software functional modules. It should be noted that, the division of the modules in the present application is illustrative, and is merely a logic function division, and other division manners may be implemented in practice.

Fig. 12 is a schematic structural diagram of an apparatus 1200 for determining gray scale values according to the present application. The apparatus 1200 includes:

the first obtaining module 1201 is configured to obtain an initial gray-scale value of the display device at an initial brightness level, where the initial brightness level is used to represent a brightness level of the display device in a current display state, and the initial gray-scale value is used to represent a brightness of the display device at the initial brightness level.

The second obtaining module 1202 is configured to obtain, when the fingerprint light spot is excited, a target gray-scale mapping coefficient and a reference brightness level, where the target gray-scale mapping coefficient is a coefficient corresponding to when the display device is switched from the initial brightness level to the reference brightness level.

The determining module 1203 is configured to determine a target gray level value according to the target gray level mapping coefficient and the initial gray level value, where a difference between a luminance of the initial gray level value at the initial luminance level and a luminance of the target gray level value at the reference luminance level is smaller than a preset threshold, and the target gray level value is used for displaying a background picture according to the target gray level value at the reference luminance level by the display device.

In some embodiments, the target grayscale mapping coefficient is one of a plurality of grayscale mapping coefficients, the plurality of grayscale mapping coefficients and a plurality of luminance levels forming a mapping relationship, the plurality of luminance levels including the initial luminance level.

In some embodiments, the reference brightness level is a highest brightness level of the display device, and the brightness corresponding to the reference brightness level is the highest brightness displayed by the display device.

In some embodiments, the reference brightness level is a display brightness value DBV4000, and the highest brightness is 1000 nit.

In some embodiments, the reference brightness level is used to characterize a brightness level threshold at which a dimming mode of the display device switches between a multi-pulse modulation mode and a direct current mode.

In some embodiments, the brightness level threshold is a display brightness value DBV1102.

In some embodiments, the target grayscale mapping coefficient is a value between 0 and 1 when the initial luminance level is less than the reference luminance level.

In some embodiments, the target grayscale mapping coefficient is 1 when the initial luminance level is greater than or equal to the reference luminance level.

In some embodiments, the target gray scale value is equal to the initial gray scale value when the initial brightness level is greater than or equal to the reference brightness level.

In some embodiments, the initial gray scale value is a first power of a gamma coefficient of a first ratio of the target gray scale value, which is the target gray scale mapping coefficient.

In some embodiments, the gamma coefficient is 2.2.

The specific manner in which the apparatus 1200 performs the method for determining the gray scale value and the resulting beneficial effects may be referred to in the related description of the method embodiments, and will not be described herein.

The embodiment of the application also provides electronic equipment, which comprises the processor. The electronic device provided in this embodiment may be the terminal device 100 shown in fig. 1, and is configured to perform the above-described method for determining a gray-scale value. In case of an integrated unit, the terminal device may comprise a processing module, a storage module and a communication module. The processing module may be configured to control and manage actions of the terminal device, for example, may be configured to support the terminal device to execute steps executed by the display unit, the detection unit, and the processing unit. The memory module may be used to support the terminal device to execute stored program codes, data, etc. And the communication module can be used for supporting the communication between the terminal equipment and other equipment.

Wherein the processing module may be a processor or a controller. Which may implement or perform the various exemplary logic blocks, modules and circuits described in connection with this disclosure. A processor may also be a combination that performs computing functions, e.g., including one or more microprocessors, digital signal processing (digital signal processer, DSP) and microprocessor combinations, and the like. The memory module may be a memory. The communication module can be a radio frequency circuit, a Bluetooth chip, a Wi-Fi chip and other equipment which interact with other terminal equipment.

In an embodiment, when the processing module is a processor and the storage module is a memory, the terminal device according to this embodiment may be a device having the structure shown in fig. 1.

The embodiment of the application also provides a computer readable storage medium, in which a computer program is stored, which when executed by a processor, causes the processor to execute the method for determining a gray scale value according to any one of the above embodiments.

The embodiment of the application also provides a computer program product, which when run on a computer, causes the computer to execute the above related steps to implement the method for determining gray scale values in the above embodiment.

The electronic device, the computer readable storage medium, the computer program product or the chip provided in this embodiment are used to execute the corresponding method provided above, so that the beneficial effects thereof can be referred to the beneficial effects in the corresponding method provided above, and will not be described herein.

In the several embodiments provided by the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of modules or units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another apparatus, or some features may be omitted or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with respect to each other may be an indirect coupling or communication connection via interfaces, devices, or units, and the replacement units may or may not be physically separate, and the components shown as units may be one physical unit or multiple physical units, that is, may be located in one place, or may be distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiments of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a readable storage medium. Based on such understanding, the technical solution of the embodiments of the present application may be essentially or a part contributing to the prior art or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium, including several instructions for causing a device (may be a single-chip microcomputer, a chip or the like) or a processor (processor) to perform all or part of the steps of the methods of the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read Only Memory (ROM), a random access memory (random access memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.

Claims

1. A method of determining gray scale values, comprising:

acquiring an initial gray scale value of a display device under an initial brightness level, wherein the initial brightness level is used for representing the brightness level of the display device in a current display state, and the initial gray scale value is used for representing the brightness of the display device under the initial brightness level;

when a fingerprint light spot is excited, a target gray-scale mapping coefficient and a reference brightness level are obtained, wherein the target gray-scale mapping coefficient is a coefficient corresponding to the display device when the initial brightness level is switched to the reference brightness level;

determining a target gray scale value according to the target gray scale mapping coefficient and the initial gray scale value, wherein the difference value between the brightness of the initial gray scale value under the initial brightness level and the brightness of the target gray scale value under the reference brightness level is smaller than a preset threshold value, and the target gray scale value is used for displaying a background picture according to the target gray scale value under the reference brightness level by the display device.

2. The method of claim 1, wherein the target gray scale mapping coefficient is one of a plurality of gray scale mapping coefficients, the plurality of gray scale mapping coefficients and a plurality of brightness levels forming a mapping relationship, the plurality of brightness levels including the initial brightness level.

3. The method of claim 2, wherein the reference brightness level is a highest brightness level of the display device, and the brightness corresponding to the reference brightness level is a highest brightness displayed by the display device.

4. A method according to claim 3, wherein the reference brightness level is a display brightness value DBV4000 and the highest brightness is 1000 nit.

5. The method of claim 2, wherein the reference brightness level is used to characterize a brightness level threshold at which a dimming mode of the display device switches between a multi-pulse modulation mode and a direct current mode.

6. The method of claim 5, wherein the brightness level threshold is a display brightness value DBV1102.

7. The method of claim 5 or 6, wherein the target gray scale mapping coefficient is a value between 0 and 1 when the initial brightness level is less than the reference brightness level.

8. The method of claim 7, wherein the target grayscale mapping coefficient is 1 when the initial luminance level is greater than or equal to the reference luminance level.

9. The method of claim 7, wherein the target gray scale value is equal to the initial gray scale value when the initial brightness level is greater than or equal to the reference brightness level.

10. The method according to any one of claims 1 to 9, wherein the initial gray-scale value is a first power of a gamma coefficient of the first ratio of the target gray-scale value, which is the target gray-scale mapping coefficient.

11. The method of claim 10, wherein the gamma coefficient is 2.2.

12. A chip, wherein the chip comprises a processor; the processor is configured to read and execute a computer program stored in a memory to perform the method of any one of claims 1 to 11.

13. An electronic device, comprising: a processor, a memory, and an interface;

the processor, the memory and the interface cooperate to cause the electronic device to perform the method of any one of claims 1 to 11.

14. A computer readable storage medium, characterized in that the computer readable storage medium has stored therein a computer program which, when executed by a processor, causes the processor to perform the method of any of claims 1 to 11.