CN104333704B - A kind of method for previewing, device and the terminal of scene of taking pictures - Google Patents

Abstract

The present invention is applicable to the technical field of terminals, and provides a preview method, device and terminal for photographing scenes, including: starting a first camera and a second camera, the first camera and the second camera are adjacent and located at the same shooting plane; when a shutter instruction is detected, the first camera is triggered to take pictures of the current scene; while the first camera takes pictures of the current scene, the picture of the current scene imaged by the second camera is real-time Output to the display screen of the terminal as a preview image. In the present invention, one camera performs the photographing action, another camera synchronously generates a real-time picture of the photographing scene, and displays it on the display screen of the terminal as a preview picture, which overcomes the defect that a single camera cannot output a preview picture during the exposure process.

Description

A preview method, device and terminal of a photographing scene

technical field

The invention belongs to terminal technology, and in particular relates to a method, device and terminal for previewing a photographing scene.

Background technique

At present, the camera function has become one of the essential functions of consumer electronic products such as mobile phones. Users have become accustomed to using mobile phones to record and share life images anytime and anywhere, and enjoy the fun brought by digital life.

When a user takes a photo with a mobile phone under low light conditions, in order to ensure the brightness of the photo, it is usually necessary to increase the exposure of the photo by extending the exposure time. The exposure time can be extended to several minutes or even dozens of minutes. Here During the process, the camera cannot output images, therefore, the user cannot realize the real-time preview of the camera scene through the display screen of the mobile phone.

Contents of the invention

The purpose of the embodiments of the present invention is to provide a preview method, device and terminal of a photographing scene, aiming at solving the current problem that the user cannot preview the photographing scene in real time during the exposure process of the mobile phone photographing.

In a first aspect, there is provided a method for previewing a photographing scene, comprising: starting a first camera and a second camera, the first camera and the second camera are adjacent and located on the same shooting plane; when a shutter instruction is detected , triggering the first camera to take pictures of the current scene; while the first camera is taking pictures of the current scene, outputting the picture of the current scene imaged by the second camera to the display screen of the terminal in real time, as a preview screen.

In a first possible implementation manner of the first aspect, the method further includes: while the first camera is taking pictures of the current scene, superimposing and displaying the current exposure of the first camera on the preview screen time.

In a second possible implementation manner of the first aspect, a resolution of the first camera is higher than a resolution of the second camera.

In a third possible implementation manner of the first aspect, while the first camera is taking pictures of the current scene, outputting the picture of the current scene imaged by the second camera to the display of the terminal in real time In the screen, as a preview image, it includes: when the first camera starts to take pictures of the current scene, start timing the current exposure time of the first camera; when the timing exceeds the preset duration, And when the first camera is still taking pictures of the current scene, output the picture of the current scene imaged by the second camera to the display screen of the terminal in real time as a preview picture.

In a fourth possible implementation manner of the first aspect, the method further includes: detecting an instruction to stop taking pictures, and terminating the action of taking pictures of the current scene by the first camera.

In a second aspect, a device for previewing a photographing scene is provided, including: an activation unit configured to activate a first camera and a second camera, the first camera and the second camera are adjacent and located on the same photographing plane; A unit configured to trigger the first camera to take pictures of the current scene when a shutter instruction is detected; a preview unit configured to image the second camera while the first camera takes pictures of the current scene The picture of the current scene is output to the display screen of the terminal in real time as a preview picture.

In a first possible implementation manner of the second aspect, the device further includes: a display unit configured to superimpose and display the first The current exposure time of a camera.

In a second possible implementation manner of the second aspect, the resolution of the first camera is higher than the resolution of the second camera.

In a third possible implementation manner of the second aspect, the preview unit includes: a timing subunit, configured to, when the first camera starts to take pictures of the current scene, start the recording of the first camera Timing of the current exposure time; an output subunit, configured to, when the timing exceeds a preset duration and the first camera is still taking pictures of the current scene, image the second camera The picture describing the current scene is output to the display screen of the terminal in real time as a preview picture.

In a fourth possible implementation manner of the second aspect, the device further includes: a terminating unit, configured to detect an instruction to terminate the photographing, and terminate the photographing action of the first camera on the current scene.

In a third aspect, a terminal is provided, and the terminal includes the above-mentioned apparatus for previewing a photographed scene.

In a first possible implementation manner of the third aspect, the terminal includes a smart phone or a tablet.

In the embodiment of the present invention, one camera performs the photographing action, and another camera synchronously generates a real-time picture of the photographing scene, and displays it as a preview picture on the display screen of the terminal, which overcomes the defect that a single camera cannot output a preview picture during the exposure process.

Description of drawings

Fig. 1 is the implementation flowchart of the method for previewing the photographing scene provided by the embodiment of the present invention;

Fig. 2 is an example diagram of positions of a first camera and a second camera provided by an embodiment of the present invention;

Fig. 3 is a flow chart of realizing a preview method of a photographing scene provided by another embodiment of the present invention;

FIG. 4 is a schematic diagram of a preview screen of a display screen of a terminal provided by an embodiment of the present invention;

FIG. 5 is a specific implementation flow chart of the method S103 for previewing a photographing scene provided by an embodiment of the present invention;

Fig. 6 is a flow chart of realizing a preview method of a photographing scene provided by another embodiment of the present invention;

Fig. 7 is a structural block diagram of a preview device for photographing a scene provided by an embodiment of the present invention;

Fig. 8 is a block diagram of a partial structure of a mobile phone related to a terminal provided by an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The method and device for previewing a photographed scene provided by the embodiments of the present invention can be applied to terminal devices integrating a camera and a display screen, including smart phones, tablets, PDAs (Personal Digital Assistant, PDA), cameras, etc., wherein, The camera in the terminal is used to realize the functions of taking pictures and recording videos, and the display screen is used to realize the preview function of the taking pictures, that is, by displaying the pictures currently captured by the camera in real time, the user can preview the real-time taking pictures.

Fig. 1 shows the implementation process of the method for previewing the scene of photographing provided by the embodiment of the present invention, which is described in detail as follows:

In S101, start a first camera and a second camera, where the first camera and the second camera are adjacent and located on the same shooting plane.

In this embodiment, two cameras are configured on the terminal at the same time, wherein the first camera and the second camera are adjacent cameras located on the same shooting plane, and the positional relationship between the two cameras needs to satisfy: The distance of the subject is basically the same, and the shooting angles of the two cameras relative to the subject are basically the same, which means that the difference between the distance or the shooting angle is so small that it can be ignored. Based on the above positional relationship, the two cameras The photos taken by two cameras for the same subject are basically the same. FIG. 2 shows a specific implementation manner in which the first camera 21 and the second camera 22 are configured on a mobile phone 23 as an implementation example.

In this embodiment, the running process of the operating system of the terminal is monitored, and when it is detected that the "camera" application program in the operating system is called to run in the foreground, the first camera and the second camera of the terminal are started at the same time.

In S102, when a shutter instruction is detected, the first camera is triggered to take pictures of the current scene.

In this embodiment, the ways of issuing the shutter command include but are not limited to the following: the shutter command is issued by pressing a physical button of the terminal, and accordingly, it needs to be determined by detecting whether the circuit connected to the physical button is connected. The release of the shutter command; or, by pressing the virtual key on the terminal touch screen to issue the shutter command, correspondingly, it is necessary to determine whether the circuit of the screen area where the virtual key is located is conductive to determine the release of the shutter command; or, by voice To issue a shutter command, correspondingly, it is necessary to receive voice data through the microphone device of the terminal, and analyze the voice data to determine the release of the shutter command.

When the shutter command is issued, one of the cameras in the dual cameras is triggered to take a photo of the scene currently being imaged.

In S103, while the first camera is taking pictures of the current scene, the picture of the current scene imaged by the second camera is output to a display screen of the terminal in real time as a preview picture.

When the first camera is taking pictures of the current scene, because the first camera is in the exposure process, it cannot output images to the display screen of the terminal, and the display screen of the terminal can only display a black picture. Therefore, the same The scene is imaged, and the imaged picture is output to the display screen of the terminal in real time, so that the display screen of the terminal can also display the real-time image of the photographed scene during the exposure imaging process of the first camera. Specifically, the picture captured by the second camera generates an optical image through its lens, and then projects it on the sensor, and then the optical image is converted into an electrical signal, and the electrical signal is converted into a digital signal through analog-to-digital conversion, and the digital signal is processed by DSP , and then sent to the terminal processor for processing, and finally output to the display screen of the terminal, becoming a real-time preview screen that the user can see.

Through the embodiment shown in Figure 1, during the process of one of the cameras taking pictures, the other camera synchronously generates a real-time picture of the scene being taken, and displays it on the display screen of the terminal as a preview picture, so that the user can take a picture of the exposure and imaging of the camera. During the process, various details of the photographed scene can also be observed in real time. Especially under the shooting conditions where the light is dark and the exposure time is long (maybe as long as several minutes to tens of minutes), the preview solution of the above shooting scene can help the user to observe whether there is any abnormality in the shooting scene during the exposure process. . For example, the exposure time required for shooting a brightly lit night scene is 3 minutes. During this process, if there are moving people in the shooting scene, long portraits will appear in the final output photo due to the long exposure time. Smearing causes the photos to be invalidated, and wastes time and system energy consumption in vain. Using the embodiment shown in Figure 1, the user can find abnormalities in the shooting scene in time and stop shooting as soon as possible, avoiding time and system energy consumption and resource consumption. waste.

As an embodiment of the present invention, as shown in Figure 3, the method also includes:

S104. While the first camera is taking pictures of the current scene, superimpose and display the current exposure time of the first camera on the preview screen.

This embodiment can quantify the exposure process of photographing, which helps the user to better understand the current photographing process and the exposure time parameters in real time. Figure 4 shows a specific implementation of superimposing the current exposure time on the preview screen, as shown in Figure 4, the exposure time can be dynamically superimposed on the border area of the display screen, without affecting the user's observation of the details of the preview screen , which has the effect of prompting the current photo exposure process.

In the embodiment of the present invention, the first camera is responsible for taking pictures of the current scene, and the second camera is responsible for generating a preview image of the current scene. Therefore, each camera has different requirements for its own frame resolution. As an embodiment of the present invention, the resolution of the first camera is higher than the resolution of the second camera.

The resolution is used to characterize the clarity of the photos taken by the camera, and the higher the resolution of the camera, the clearer the photos or videos taken by it. Since the second camera is only used to generate preview images, and the display screen of the terminal is usually only four or five inches in size, the ordinary resolution is sufficient to meet the user's preview needs. Therefore, the second camera has lower requirements for resolution. The first camera needs to be responsible for the final imaging, and a higher resolution can be configured for the first camera. Therefore, in this embodiment, the resolution of the configured first camera is higher than that of the second camera. In this way, when the second camera generates a preview image, the resolution of the generated image is low, with The resulting effect is that the image processor needs to process relatively less data when calculating the contrast value of the image, which can effectively reduce the power consumption of the image processor and achieve the effect of energy saving.

As an embodiment of the present invention, it is possible to decide whether to enable the second camera to generate a preview image according to the length of the exposure time in the actual photographing process, as shown in Figure 5, S103 is specifically:

In S501, when the first camera starts to take pictures of the current scene, start counting the current exposure time of the first camera.

In S502, when the counted time exceeds the preset duration and the first camera is still taking pictures of the current scene, output the picture of the current scene imaged by the second camera to the on the display screen of the terminal as a preview screen.

In this embodiment, the preset duration is used as the threshold for determining whether to enable the second camera to generate a preview image. If the exposure time of the first camera exceeds the preset duration, it indicates that the first camera is currently performing a long exposure, then Enable the second camera to generate a preview image, which is convenient for users to observe the details of the picture taken during the long exposure process; if the first camera has taken a picture before reaching the preset duration, it means that the current photo taken by the first camera does not need After a long time of exposure, it is meaningless to display a preview image on the terminal display screen during this period, so the preview image generated by the second camera is no longer displayed, thereby effectively saving system resources.

As an implementation example of the present invention, the preset duration may be set to 5 seconds.

As an embodiment of the present invention, as shown in FIG. 6, after S103, the method further includes:

S105. Detecting an instruction to terminate the photographing, and terminating the photographing action of the first camera on the current scene.

In this embodiment, during the exposure process before the first camera completes the photoshoot, once the user observes an abnormality in the photoshoot scene through the preview image generated by the second camera, for example, the terminal or the plane supporting the terminal shakes, or If there is an unexpected object movement in the shooting scene, the user can issue a stop shooting command at any time. After detecting the stop shooting command, the current shooting action of the first camera will be terminated immediately, and the shooting mode will be exited, so that the user can start as soon as possible. The next time you take a picture, you avoid wasting time and system resources.

In the embodiment of the present invention, one camera performs the photographing action, and another camera synchronously generates a real-time picture of the photographing scene, and displays it on the display screen of the terminal as a preview picture, which overcomes the defect that a single camera cannot output a preview picture during the exposure process, It enables users to observe various details of the photographing scene in real time during the exposure and imaging process of the camera, discover abnormalities in the photographing scene in time, and stop shooting as soon as possible, avoiding waste of time, system energy consumption, and resources.

It should be understood that in the embodiment of the present invention, the sequence numbers of the above-mentioned processes do not mean the order of execution, and the execution order of each process should be determined by its function and internal logic, rather than the implementation process of the embodiment of the present invention. constitute any limitation.

Corresponding to the method for previewing a photographing scene provided by an embodiment of the present invention, FIG. 7 shows a structural block diagram of a device for previewing a photographing scene provided by an embodiment of the present invention. The device can run on a terminal device that integrates a camera and a display screen. , such as smartphones, tablets, PDAs, cameras, etc. For ease of description, only the parts related to this embodiment are shown.

Referring to Figure 7, the device includes:

The activation unit 71 is configured to activate a first camera and a second camera, the first camera and the second camera are adjacent and located on the same shooting plane.

The photographing unit 72, when a shutter instruction is detected, triggers the first camera to photograph the current scene.

The preview unit 73 is configured to output the picture of the current scene imaged by the second camera to the display screen of the terminal in real time as a preview picture while the first camera is taking pictures of the current scene.

Optionally, the device also includes:

The display unit is configured to superimpose and display the current exposure time of the first camera on the preview screen while the first camera is taking pictures of the current scene.

Optionally, the resolution of the first camera is higher than the resolution of the second camera.

Optionally, the preview unit 73 includes:

The timing subunit is configured to start timing the current exposure time of the first camera when the first camera starts to take pictures of the current scene.

The output subunit is configured to output the picture of the current scene imaged by the second camera to the on the display screen of the terminal as a preview screen.

Optionally, the device also includes:

The terminating unit detects an instruction to terminate the photographing, and terminates the photographing action of the first camera on the current scene.

FIG. 8 is a block diagram showing a partial structure of a mobile phone related to the terminal provided by the embodiment of the present invention. Referring to FIG. 8 , the mobile phone includes: a radio frequency (Radio Frequency, RF) circuit 810, a memory 820, an input unit 830, a display unit 840, a first camera 850, a second camera 860, and a processor 870 and other components. Those skilled in the art can understand that the structure of the mobile phone shown in FIG. 8 does not constitute a limitation to the mobile phone, and may include more or less components than shown in the figure, or combine some components, or arrange different components.

The following is a specific introduction to each component of the mobile phone in conjunction with Figure 8:

The RF circuit 810 can be used for sending and receiving information or receiving and sending signals during a call. In particular, after receiving the downlink information from the base station, it is processed by the processor 870; in addition, the designed uplink data is sent to the base station. Generally, an RF circuit includes, but is not limited to, an antenna, at least one amplifier, a transceiver, a coupler, a low noise amplifier (Low Noise Amplifier, LNA), a duplexer, and the like. In addition, RF circuitry 810 may also communicate with networks and other devices via wireless communications. The above-mentioned wireless communication can use any communication standard or protocol, including but not limited to Global System of Mobile Communication (Global System of Mobile communication, GSM), General Packet Radio Service (General Packet Radio Service, GPRS), Code Division Multiple Access (Code Division Multiple Access) , CDMA), Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE)), email, Short Messaging Service (SMS), etc.

The memory 820 can be used to store software programs and modules, and the processor 870 executes various functional applications and data processing of the mobile phone by running the software programs and modules stored in the memory 820 . The memory 820 can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application program required by a function (such as a sound playback function, an image playback function, etc.); Data created by the use of mobile phones (such as audio data, phonebook, etc.), etc. In addition, the memory 820 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid-state storage devices.

The input unit 830 can be used to receive input numbers or character information, and generate key signal input related to user settings and function control of the mobile phone 800 . Specifically, the input unit 830 may include a touch panel 831 and other input devices 832 . The touch panel 831, also referred to as a touch screen, can collect touch operations of the user on or near it (for example, the user uses any suitable object or accessory such as a finger or a stylus on the touch panel 831 or near the touch panel 831). operation), and drive the corresponding connection device according to the preset program. Optionally, the touch panel 831 may include two parts, a touch detection device and a touch controller. Among them, the touch detection device detects the user's touch orientation, and detects the signal brought by the touch operation, and transmits the signal to the touch controller; the touch controller receives the touch information from the touch detection device, converts it into contact coordinates, and sends it to the to the processor 870, and can receive and execute commands sent by the processor 870. In addition, the touch panel 831 can be implemented in various types such as resistive, capacitive, infrared, and surface acoustic wave. In addition to the touch panel 831 , the input unit 830 may also include other input devices 832 . Specifically, other input devices 832 may include but not limited to one or more of a physical keyboard, function keys (such as volume control keys, switch keys, etc.), trackball, mouse, joystick, and the like.

The display unit 840 may be used to display information input by or provided to the user and various menus of the mobile phone. The display unit 840 may include a display screen 841. Optionally, the display screen 841 may be configured in the form of a liquid crystal display (Liquid Crystal Display, LCD), an organic light-emitting diode (Organic Light-Emitting Diode, OLED), or the like. Further, the touch panel 831 can cover the display screen 841, and when the touch panel 831 detects a touch operation on or near it, the touch operation is sent to the processor 870 to determine the type of the touch event, and then the processor 870 according to the touch event The type provides a corresponding visual output on the display screen 841 . Although in FIG. 8 , the touch panel 831 and the display screen 841 are used as two independent components to realize the input and input functions of the mobile phone, in some embodiments, the touch panel 831 and the display screen 841 can be integrated and Realize the input and output functions of the mobile phone.

The processor 870 is the control center of the mobile phone, and uses various interfaces and lines to connect various parts of the entire mobile phone. By running or executing software programs and/or modules stored in the memory 820, and calling data stored in the memory 820, execution Various functions and processing data of the mobile phone, so as to monitor the mobile phone as a whole. Optionally, the processor 870 may include one or more processing units; preferably, the processor 870 may integrate an application processor and a modem processor, wherein the application processor mainly processes the operating system, user interface and application programs, etc. , the modem processor mainly handles wireless communications. It can be understood that, the foregoing modem processor may not be integrated into the processor 870 .

Although not shown, the mobile phone 800 may also include a power supply, a wireless module, a Bluetooth module, an audio circuit, a sensor, etc., which will not be repeated here.

In the embodiment of the present invention, the processor 870 included in the terminal also has the following functions: a method for previewing a photographed scene, including:

Start the first camera and the second camera, the first camera and the second camera are adjacent and located on the same shooting plane;

When a shutter instruction is detected, trigger the first camera to take pictures of the current scene;

While the first camera is taking pictures of the current scene, the picture of the current scene imaged by the second camera is output to the display screen of the terminal in real time as a preview picture.

Further, the method also includes:

While the first camera is taking pictures of the current scene, the current exposure time of the first camera is superimposed and displayed on the preview screen.

Further, the resolution of the first camera is higher than the resolution of the second camera.

Further, while the first camera is taking pictures of the current scene, outputting the picture of the current scene imaged by the second camera to the display screen of the terminal in real time, the preview picture includes:

When the first camera starts to take pictures of the current scene, start timing the current exposure time of the first camera;

When the counted time exceeds the preset duration and the first camera is still taking pictures of the current scene, output the picture of the current scene imaged by the second camera to the display screen of the terminal in real time , as a preview screen.

Further, the method also includes:

An instruction to terminate the photographing is detected, and the photographing action of the first camera on the current scene is terminated.

Those skilled in the art can appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

Those skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods may be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or May be integrated into another system, or some features may be ignored, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit.

If the functions described above are realized in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk and other media that can store program codes. .

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (10)

1. A method for previewing a photographed scene, comprising: When it is detected that the camera application in the operating system is called to run in the foreground, start the first camera and the second camera at the same time, the first camera and the second camera are adjacent and located on the same shooting plane; When a shutter instruction is detected, trigger the first camera to take pictures of the current scene; While the first camera is taking pictures of the current scene, in the process of exposure imaging, output the picture of the current scene imaged by the second camera to the display screen of the terminal in real time, as a preview picture, including: When the first camera starts to take pictures of the current scene, start timing the current exposure time of the first camera; When the counted time exceeds the preset duration and the first camera is still taking pictures of the current scene, during the exposure imaging process, the picture of the current scene imaged by the second camera Real-time output to the display screen of the terminal as a preview screen; If the first camera finishes taking pictures before the preset duration, the preview image generated by the second camera will not be displayed during the exposure and imaging process. 2. The method of claim 1, further comprising: While the first camera is taking pictures of the current scene, the current exposure time of the first camera is superimposed and displayed on the preview screen. 3. The method according to claim 1, wherein the resolution of the first camera is higher than the resolution of the second camera. 4. The method of claim 1, further comprising: An instruction to terminate the photographing is detected, and the photographing action of the first camera on the current scene is terminated. 5. A preview device for photographing a scene, characterized in that it comprises: The starting unit is used to start the first camera and the second camera at the same time when it is detected that the camera application in the operating system is called to run in the foreground, the first camera and the second camera are adjacent and located on the same shooting plane ; A photographing unit, configured to trigger the first camera to photograph the current scene when a shutter instruction is detected; The preview unit is configured to output the picture of the current scene imaged by the second camera to the display screen of the terminal in real time during the exposure imaging process while the first camera is taking pictures of the current scene, as preview screen; The preview unit includes: A timing subunit, configured to start timing the current exposure time of the first camera when the first camera starts to take pictures of the current scene; An output subunit, configured to, when the counted time exceeds a preset duration and the first camera is still taking pictures of the current scene, during the exposure imaging process, image the second camera The picture of the current scene is output to the display screen of the terminal in real time as a preview picture; if the first camera has finished taking pictures before reaching the preset duration, then during the exposure imaging process, no A preview image generated by shooting with the second camera is displayed. 6. The device of claim 5, further comprising: The display unit is configured to superimpose and display the current exposure time of the first camera on the preview screen while the first camera is taking pictures of the current scene. 7. The device according to claim 5, wherein the resolution of the first camera is higher than the resolution of the second camera. 8. The device of claim 5, further comprising: The terminating unit is configured to detect an instruction to terminate the photographing, and terminate the photographing action of the first camera on the current scene. 9. A terminal, characterized in that the terminal comprises the device for previewing a photographed scene according to any one of claims 5 to 8. 10. The terminal according to claim 9, wherein the terminal comprises a smart phone or a tablet.