CN111477147A

CN111477147A - Image processing method and device and electronic equipment

Info

Publication number: CN111477147A
Application number: CN202010273526.2A
Authority: CN
Inventors: 郑明剑; 金海鹏
Original assignee: Kunshan Taixin Microelectronics Co ltd
Current assignee: Kunshan Taixin Microelectronics Co ltd
Priority date: 2020-04-09
Filing date: 2020-04-09
Publication date: 2020-07-31
Anticipated expiration: 2040-04-09
Also published as: CN111477147B

Abstract

The embodiment of the application provides an image processing method and device and electronic equipment. The image processing method comprises the following steps: under the condition that partial display areas of the display screen need to be updated, determining a sub-display area to be updated currently, wherein the display area of the display screen is divided into a plurality of sub-display areas, and any two sub-display areas are not overlapped; determining a final image block corresponding to the currently to-be-updated sub-display area; and sending the final image block corresponding to the sub-display area to be updated and the position information of the sub-display area to be updated to a display driving circuit, so that the display driving circuit replaces the pixel data at the corresponding position in the previous frame of image stored by the display driving circuit with the pixel data of the final image block corresponding to the sub-display area to be updated to obtain a new frame of image. By adopting the image processing method, the data volume transmitted by the external interface is low, and the operation amount of image processing is low.

Description

Image processing method and device and electronic equipment

Technical Field

The present application relates to the field of display technologies, and in particular, to an image processing method and apparatus, and an electronic device.

Background

Wearable electronic equipment such as intelligent wrist-watch, intelligent bracelet walk into masses consumption field gradually. The display screen is more and more refined, the screen with 240 × 240 pixels, 16bit color and higher resolution is more and more used, and meanwhile, the refreshing frequency of the screen is also higher, at least 20 frames per second is generally required, and the refreshing speed of 30 frames per second, even 60 frames per second is more likely to be achieved for the high-end screen. For cost control, the processor in the wearable electronic device generally adopts a processor with low computational performance, memory capacity and interface speed, such as a Micro Controller Unit (MCU). How to realize higher image resolution and better image quality under the premise of smaller computation amount, smaller memory capacity and lower interface speed becomes a technical problem to be solved urgently.

Disclosure of Invention

The application provides an image processing method, an image processing device and an electronic device, which are used for at least partially solving the technical problems in the prior art.

An embodiment of the present application provides an image processing method, including: under the condition that partial display areas of the display screen need to be updated, determining a sub-display area to be updated currently, wherein the display area of the display screen is divided into a plurality of sub-display areas, and any two sub-display areas are not overlapped;

determining a final image block corresponding to the currently to-be-updated sub-display area;

and sending the final image block corresponding to the sub-display area to be updated and the position information of the sub-display area to be updated to a display driving circuit, so that the display driving circuit replaces the pixel data at the corresponding position in the previous frame of image stored by the display driving circuit with the pixel data of the final image block corresponding to the sub-display area to be updated to obtain a new frame of image.

In some optional embodiments, determining a final image block corresponding to the currently to-be-updated sub-display area includes:

and reading the final image block corresponding to the sub-display area to be updated currently from the nonvolatile memory.

reading a background image block corresponding to the currently to-be-updated sub-display area from a nonvolatile memory;

determining a foreground image corresponding to the sub-display area to be updated, wherein part of pixels of the foreground image are transparent pixels, and part of pixels are non-transparent pixels;

and superposing the foreground images on the background image blocks corresponding to the sub-display areas to be updated to obtain the final image blocks, wherein in the final image blocks, the pixel data at the positions corresponding to the transparent pixels are the pixel data of the background images at the corresponding positions, and the pixel data at the positions corresponding to the non-transparent pixels of the foreground images are the pixel data of the foreground images at the corresponding positions, under the condition that the number of the foreground images corresponding to the sub-display areas to be updated is 1 or the foreground images corresponding to the sub-display areas to be updated are not overlapped with each other.

In some optional embodiments, determining a foreground image corresponding to the sub-display area to be updated includes:

reading a foreground image corresponding to the sub-display area to be updated from a nonvolatile memory, wherein pixel data in the foreground image is stored in the nonvolatile memory in a first digit;

and converting the pixel data with the first digit into pixel data with a second digit according to a set mapping table, wherein each pixel data of the background image occupies the second digit, and the second digit is greater than the first digit.

In some alternative embodiments, the resolution of the foreground image is less than the resolution of the background image.

In some optional embodiments, a foreground image is selected from the foreground images residing in the memory;

and carrying out transformation operation on the selected foreground image to obtain a foreground image corresponding to the sub-display area to be updated.

In some optional embodiments, the pixels of the electronic device are arranged in an array, the sub-display area is rectangular, and the extending directions of two sides of the rectangle are two directions of the array arrangement, respectively.

In some optional embodiments, further comprising: and under the condition that the display screen needs to be updated into a background image in a full screen mode, transmitting each background image block forming a complete frame of background image in the nonvolatile memory to an output cache block by block, so that the display driving circuit acquires the background image block from the output cache, and replacing pixel data at a corresponding position in a previous frame of image stored by the display driving circuit with pixel data of a corresponding background image block to obtain a new frame of image.

In some alternative embodiments, the foreground images have a priority; in the step of superimposing the foreground image on the background image block corresponding to the sub-display area to be updated, under the condition that the foreground image corresponding to the sub-display area to be updated is overlapped, at the overlapping position of the foreground image, the non-transparent pixel data of the foreground image with the highest priority is used as the pixel data of the final image block at the corresponding position, and the pixel data of the background image at the overlapping position of the transparent pixel is used as the pixel data of the final image block at the corresponding position.

An embodiment of the present application provides an image processing apparatus, comprising a memory and a processor, wherein the memory stores instructions, and the instructions are executed by the processor to execute the image processing method.

An embodiment of the present application provides an image processing apparatus including: the device comprises a first determining module, a second determining module and a display module, wherein the first determining module is used for determining a sub-display area to be updated currently under the condition that part of the display area of the display screen needs to be updated, the display area of the display screen is divided into a plurality of sub-display areas, and any two sub-display areas are not overlapped;

the second determining module is used for determining a final image block corresponding to the currently to-be-updated sub-display area;

and the sending module is used for sending the final image block corresponding to the sub-display area to be updated currently and the position information of the sub-display area to be updated currently to a display driving circuit, so that the display driving circuit replaces the pixel data at the corresponding position in the previous frame of image stored by the display driving circuit with the pixel data of the final image block corresponding to the sub-display area to be updated currently to obtain a new frame of image.

In some optional embodiments, the display device further includes a transparent transmission module, configured to, when the display screen needs to be updated to a background image in a full screen, transparently transmit each background image block constituting a complete frame of background image in the nonvolatile memory to the output cache block by block, so that the display driving circuit acquires the background image block from the output cache, and replaces pixel data at a corresponding position in a previous frame of image stored in the display driving circuit with pixel data of a corresponding background image block to obtain a new frame of image. An embodiment of the present application provides an electronic device, including the above-mentioned image processing apparatus, and including a display driving circuit and a display screen driven by the display driving circuit; the display driving circuit is used for storing one frame of display data, updating corresponding pixel data in the one frame of display data according to the obtained final image block and the corresponding position information, and driving the display screen according to the updated one frame of display data.

In some optional embodiments, the electronic device is a wearable electronic device.

According to at least one embodiment of the application, in order to update one frame of display image, only the operation processing needs to be performed on the display data required by the partial sub-display area, and only the display data required by the partial sub-display area needs to be provided to the display driving circuit, so that the refreshing of one frame of display image of the electronic device is realized. The image processing has small operation amount and less interface data transmission amount. Therefore, under the conditions that the computing capacity of the electronic equipment is poor and the interface transmission speed is low, high-resolution and high-image-quality display can still be realized.

Drawings

Fig. 1 is a flowchart of an image processing method according to an embodiment of the present application.

Fig. 2 is a flowchart illustrating a subdivision process of a part of the steps of an image processing method according to an embodiment of the present application.

Fig. 3 is a schematic diagram of display area division and foreground image distribution of an electronic device in an embodiment of the present application.

Fig. 4 is a schematic configuration diagram of an electronic device according to an embodiment of the present application.

Fig. 5 is a schematic diagram of display area division and foreground image distribution of an electronic device in an embodiment of the present application.

Fig. 6 is a schematic structural diagram of an image processing apparatus according to an embodiment of the present application.

Fig. 7 is a schematic structural diagram of an image processing apparatus according to another embodiment of the present application.

Detailed Description

In order to make the technical solutions of the present application better understood by those skilled in the art, the present application is described in further detail below with reference to the accompanying drawings and the detailed description.

Unless otherwise defined, technical or scientific terms used in the embodiments of the present application should have the ordinary meaning as understood by those having ordinary skill in the art to which the present application belongs. As used in this application, the terms "first," "second," and the like do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the word "comprise", or "comprises", and the like, means that the element or item preceding the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items.

The embodiment of the application provides an image processing method. From a device perspective, the execution subject may be an electronic device, and more specifically, an image processing chip (GPU), a Micro Control Unit (MCU), or the like therein; from the program perspective, the execution main body may accordingly be a program loaded on these electronic devices. Referring to fig. 1, the image processing includes the following steps.

Step 101, under the condition that a part of display areas of a display screen need to be updated, determining a sub-display area to be updated currently, wherein the display area of the display screen is divided into a plurality of sub-display areas, and any two sub-display areas are not overlapped.

The electronic device is, for example, a smart watch. Referring to FIG. 3, the display area of the smart watch is divided into 16 rectangular sub-display areas of 4 rows and 4 columns, numbered B0-B15 in that order. During most of the time that the intelligent watch is operated, only part of the contents displayed in the sub-display areas need to be updated or changed, and the contents displayed in the rest sub-display areas are unchanged for a long time.

In particular, fig. 3 shows a scenario in which the smart watch displays a stopwatch. The reading of the stopwatch at the previous time was 00:01:22, and the reading at the next time became 00:01: 23. Then the sub-display area in which the current display content is changed has only the sub-display area labeled B6.

And 102, determining a final image block corresponding to the currently to-be-updated sub-display area.

Because the number of the sub-display areas with changed current display content is small, the display data required by the small number of the sub-display areas only needs to be calculated. Each final image block is displayed in one of the sub-display areas. The size and shape of the final image block and the size and shape of the corresponding sub-display area are the same. For example, if one sub-display region is a 40 × 20 rectangle, then the pixels in the corresponding final image block are also a 40 × 20 matrix.

Referring to fig. 3, currently only the display data required for the sub display region B6 needs to be calculated.

103, sending the final image block corresponding to the current sub-display area to be updated and the position information of the current sub-display area to be updated to a display driving circuit, so that the display driving circuit replaces the pixel data at the corresponding position in the previous frame of image stored by the display driving circuit with the pixel data of the final image block corresponding to the current sub-display area to be updated to obtain a new frame of image.

Specifically, the final image block corresponding to the currently to-be-updated sub-display area and the position information of the currently to-be-updated sub-display area may be output to the display driving circuit through the output buffer.

Referring to fig. 3, only the display data required for the sub display region B6 needs to be output currently.

The position information of the sub-display area to be updated may specifically be the number of the sub-display area, or may also be the coordinates of the sub-display area. These are all equivalent embodiments.

Since the image processing apparatus only needs to calculate image data required for a small number of sub-display regions that need to be updated, display data required for a small number of sub-display regions is also output to the display drive circuit. The image processing apparatus itself has a small amount of computation and a small amount of data to be transmitted to the display drive circuit. Therefore, the display with high resolution and rich colors can be realized under the conditions that the image processing device has low performance and the interface speed is low.

In some optional embodiments, the final image block corresponding to the currently to-be-updated sub-display area is read from the non-volatile memory.

I.e. in case the storage capacity of the non-volatile memory is sufficiently large, the final image block is pre-stored. The nonvolatile memory is, for example, a Flash memory (Flash).

Referring to fig. 5, when the clock is displayed, assuming that the position of the current minute hand is changed, the sub display regions in which the display contents are changed are only B2, B5, and B6. The display data (i.e., the final image block) corresponding to the three sub-display areas B2, B5, and B6 after the position change of the minute hand can be directly read from the non-volatile memory.

In some alternative embodiments, the foreground and background images are stored separately in non-volatile memory. In particular, the background image is stored divided into a plurality of background image blocks, so that only a small number of background image blocks need to be read from the non-volatile memory when only a few final image blocks needed for the sub-display area need to be calculated. Thereby reducing the amount of data transferred from the non-volatile memory to the memory.

Based on the above inventive concept, referring to fig. 2, determining a final image block corresponding to the currently to-be-updated sub-display area includes the following steps.

Step 1021, reading the background image block corresponding to the currently to-be-updated sub-display area from the non-volatile memory.

Referring to fig. 3, the foreground image is, for example, a plurality of digital images representing numbers 0 to 9, respectively, and a colon image. The background image is the background displayed behind the stop watch, for example a landscape (not shown in fig. 2). The resolution of the background image is the same as the resolution of the display screen of the electronic device.

Since the content displayed in the majority of the sub-display areas is usually not changed, in order to reduce the amount of data transferred from the non-volatile memory to the memory (e.g., the random access memory RAM), when calculating the display image of each frame, only the background image block corresponding to the sub-display area where the display image is changed may be read from the non-volatile memory.

Referring to fig. 4, in one particular scenario, the foreground image and background image blocks are stored in Flash (Flash). The main body for executing the image processing method is an MCU, and the whole machine is an intelligent watch. The flash memory and the MCU chip are connected through Serial Peripheral Interface (SPI) communication. The MCU chip adopts a Static Random Access Memory (SRAM). The output buffer memory in the MCU chip is in communication connection with the display driving circuit through a serial peripheral interface. The output buffer may be a single output buffer or a ping-pong output buffer. The following disclosures will be described by way of example.

In the non-volatile memory, the background image is stored in the form of a plurality of background image blocks. Each background image block has a label indicating its position in the complete background image.

And 1022, determining a foreground image corresponding to the sub-display area to be updated, where part of pixels of the foreground image are transparent pixels and part of pixels are non-transparent pixels.

A transparent pixel in the foreground image may be represented by a particular numerical value, the transparent pixel representing whether it is ultimately presented to the user or the background image at the corresponding location when superimposed on the background image. The value of the non-transparent pixel represents the gray level of the color of this pixel.

And 1023, superposing the foreground image on a background image block corresponding to the to-be-updated sub-display area to obtain the final image block, wherein in the final image block, pixel data at a position corresponding to the transparent pixel is pixel data of the background image at a corresponding position, and pixel data at a position corresponding to the non-transparent pixel of the foreground image is pixel data of the foreground image at a corresponding position, when the number of foreground images corresponding to the to-be-updated sub-display area is 1 or foreground images corresponding to the to-be-updated sub-display area are not overlapped with each other.

Optionally, determining a foreground image corresponding to the sub-display area to be updated includes: reading a foreground image corresponding to the sub-display area to be updated from a nonvolatile memory, wherein pixel data in the foreground image is stored in the nonvolatile memory in a first digit; and converting the pixel data with the first digit into pixel data with a second digit according to a set mapping table, wherein each pixel data of the background image occupies the second digit, and the second digit is greater than the first digit.

The background image is rich in color, for example, 16 bits are required to represent one pixel. The foreground image typically uses less color depth and thus has fewer colors than the background image.

The resolution of the foreground image and the resolution of the background image may be the same, for example, 240x240x4bit, and each pixel uses only 4 bits, and sometimes may be 240x240x1bit, for example, only black and white. The pointer has high resolution, and is convenient to rotate in the memory.

Of course, the resolution of the foreground image may also be lower than that of the background image, for example, the foreground image representing the hour hand is smaller and can be superimposed on both sub-display areas at most. For example, a digital image may be represented by 10x10x4 bits. Of course, if the resolution of the foreground image is low, less storage space is required in the non-volatile memory.

The color bit number of the background image directly corresponds to the representative color of the color, for example, directly indicates that the red gray scale value is 5, the green gray scale value is 6, and the blue gray scale value is 5; the binary number of 4 bits of the foreground image is an index value pointing to a color mapping table, such as 0, 1, 2, … … 15 corresponding to transparent color, color #1, color #2, color #3, … … color #15, respectively. The corresponding relationship may be fixed, or may have different corresponding relationships according to different scenes or different foreground images.

In other words, when the foreground image is stored in the non-volatile memory, each pixel data does not directly represent the gray scale of the pixel (e.g., does not directly represent the gray scale of the red component, the gray scale of the green component, and the gray scale of the blue component of the pixel), but rather serves as an index for a 16-bit or 32-bit color.

As such, the process of superimposing one pixel of the foreground image on one pixel of the background image is as follows.

For example, the background image pixel value is 0xABCD (for example, 16 bit), and the foreground image pixel index value is 0x0, since the foreground image 0x0 corresponds to transparent color, the synthesized pixel value is equal to the background image pixel value of 0 xABCD; in another example, the background pixel value is 0xAABB, the pixel index value of the foreground image is 0x2 (corresponding to color #2 being 0xC0C0), the pixel of the foreground image is opaque, so the synthesized pixel value is 0xC0C0, and so on.

Referring to fig. 3, the display data in the sub-display area denoted by reference numeral B6 needs to be updated. Only the following steps are needed: the three symbol images and character images of "2" "and" "3" are superimposed on the background image block corresponding to the sub-display area labeled B6 to obtain a final image block.

In this way, the amount of data of the foreground image transferred from the nonvolatile memory to the memory is lower. If the foreground image needs to reside in the memory, the data volume of the foreground image residing in the memory is also low.

In a specific embodiment, referring to fig. 4, 16 first storage areas a0-a15 are divided in a memory (SRAM). The first storage areas correspond to the sub-display areas one to one. Each first storage area stores 60 rows and 60 columns of pixels, each pixel being represented by a 4-bit number. Referring to fig. 3, the sub-display area to be updated is B6, and the foreground image displayed in the sub-display area labeled B6 is, for example, ": "," 2 "and" 3 ". Then according to ": "," 2 ", and" 3 "are expected to occur, the pixel data in reference a6 is updated. Of course, ": the non-overlapped region pixel data of "" 2 "" and "" 3 "" are updated to be transparent pixels. The 4-bit matrix of 60 × 60 bits may then be converted into a 16-bit matrix of 60 × 60 bits according to a mapping table, and then operated with the background image block (also the 60 × 16-bit matrix) corresponding to the sub-display area labeled B6, so as to obtain a final image block of 60 × 16 bits.

In some optional embodiments, determining a foreground image corresponding to the sub-display area to be updated includes: selecting a foreground image from the resident foreground images in the memory; and carrying out transformation operation on the selected foreground image to obtain a foreground image corresponding to the sub-display area to be updated.

The foreground images may reside in RAM for long periods of time. Of course, the desired foreground image may also be read from the non-volatile memory each time the image is updated (and if desired, an operation such as rotation may also be performed on it).

One strategy for foreground images such as clock hands is to store 60 scale images in a nonvolatile memory and read corresponding minute hand images from the nonvolatile memory when the minute hand images need to be updated. For example, when the time is switched from 5 minutes to 6 minutes, an image representing 6 minutes is read from the flash memory. In this case, the resolution of the scale of the clock hands may be small.

Of course, only one minute hand image representing 0 minute may be stored in the nonvolatile memory. When the minute hand image of 0 minute hand is stored in the memory, if the minute hand image representing 1 minute hand needs to be displayed, the minute hand image is rotated clockwise by 6 degrees.

I.e. the foreground image and the foreground image may overlap in the sub-display region to be updated, the non-transparent pixels of the foreground image with higher priority may be superimposed on the non-transparent pixels of the foreground image with lower priority.

Referring to fig. 5, there may be an overlap between the minute hand image and the hour hand image. It is possible to set whether the minute hand image is superimposed on the hour hand image or the hour hand image is superimposed on the minute hand image by setting the priority.

Optionally, referring to fig. 3 and 5, the pixels of the display screen are arranged in an array, the sub-display area is rectangular, and the extending directions of two sides of the rectangle are two directions of the array arrangement, respectively.

Of course, the display area of the display screen of the electronic device may be divided into sectors. Accordingly, the background image block is also fan-shaped.

In addition, the sizes of the sub display regions may be the same or different. For example, if the probability of the image change in the peripheral display region is lower than the probability of the image change in the middle display region in the display screen of the electronic device, the size of the peripheral sub-display region can be increased appropriately.

In some optional embodiments, the image processing method further comprises: step 100, under the condition that the display screen needs to be updated to a background image in a full screen mode, transmitting each background image block forming a complete frame of background image in the nonvolatile memory to an output cache block by block, so that the display driving circuit can obtain the background image block from the output cache, and replacing the pixel data at the corresponding position in the previous frame of image stored by the display driving circuit with the pixel data of the corresponding background image block to obtain a new frame of image.

For example, referring to fig. 4, if the display area of the current electronic device needs to display a simple background image, and the display area is different from the previous background image, a new complete frame of background image can be transparently output and cached block by block from Flash in the form of a background image block without going through the SRAM. This also reduces the amount of calculation of the MCU chip. The transmission sequence of each background image block may be agreed, or corresponding position information may be attached when each background image block is transmitted.

The content displayed in the partial sub-display area may then be updated according to the foregoing steps.

Of course, if the full screen of the electronic device needs to be refreshed into a new background image and some foreground images to be combined, a complete frame of image can be obtained by operation in the RAM, and then the complete frame of image is transmitted to the display driving circuit through the output cache.

Based on the same inventive concept, referring to fig. 6, an embodiment of the present application further provides an image processing apparatus to implement the foregoing image processing method. The image processing apparatus includes the following modules.

The first determining module 1 is configured to determine a sub-display area to be updated currently when a part of a display area of a display screen needs to be updated, where the display area of the display screen is divided into a plurality of sub-display areas, and any two sub-display areas are not overlapped.

And the second determining module 2 is configured to determine a final image block corresponding to the currently to-be-updated sub-display area.

The sending module 3 is configured to send the final image block corresponding to the current sub-display area to be updated and the position information of the current sub-display area to be updated to the display driving circuit, so that the display driving circuit replaces the pixel data at the corresponding position in the previous frame of image stored by the display driving circuit with the pixel data of the final image block corresponding to the current sub-display area to be updated to obtain a new frame of image.

Optionally, the display device further includes a transparent transmission module 4, configured to, when the display screen needs to be updated to a background image in a full screen, transparently transmit each background image block constituting a complete frame of background image in the nonvolatile memory to an output cache block by block, so that the display driving circuit obtains the background image block from the output cache, and replace the pixel data at the corresponding position in the previous frame of image stored in the display driving circuit with the pixel data of the corresponding background image block to obtain a new frame of image.

The above modules may be completely implemented by software (including firmware, resident software, micro-code, etc.), may be completely implemented by hardware, or may be implemented by a combination of software and hardware.

The specific working details of each module can refer to the image processing method of the foregoing embodiment.

Referring to fig. 7, an embodiment of the present application further provides an image processing apparatus including a memory 1000 and a processor 2000, where the memory 1000 stores instructions that when executed by the processor 2000 perform the image processing method described above.

An embodiment of the present application further provides an electronic device, including the above-mentioned image processing apparatus, and including a display driving circuit (which may be a display driving chip) and a display screen driven by the display driving circuit; the display driving circuit is used for storing the previous frame of display data, updating corresponding pixel data in the frame of display data according to the obtained final image block and the corresponding position information, and driving the display screen according to the updated frame of display data.

The display driving circuit only needs to receive display data required by part of the sub-display areas, and accordingly a new frame of display data is generated in the display driving circuit and then the new frame of display data is followed to drive the display screen to display a new frame of image.

The amount of data that the display driver circuit needs to accept is reduced and the data transfer rate requirements for the interface are correspondingly reduced.

Of course, the display driving circuit may accept the complete frame of image data block by block and then drive the display screen to display the complete frame of image.

Optionally, the electronic device is a wearable electronic device. Such as a smart watch, smart bracelet.

The embodiments in the present application are described in a progressive manner, and the same and similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the apparatus and device embodiments, since they are substantially similar to the method embodiments, their description is simplified, and reference may be made to some descriptions of the method embodiments for relevant points.

It is to be understood that the above embodiments are merely exemplary embodiments that are employed to illustrate the principles of the present application, and that the present application is not limited thereto. It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the application, and these changes and modifications are to be considered as the scope of the application.

Claims

1. An image processing method, comprising:

under the condition that partial display areas of the display screen need to be updated, determining a sub-display area to be updated currently, wherein the display area of the display screen is divided into a plurality of sub-display areas, and any two sub-display areas are not overlapped;

2. The image processing method according to claim 1, wherein determining the final image block corresponding to the currently to-be-updated sub-display area comprises:

3. The image processing method according to claim 1, wherein determining the final image block corresponding to the currently to-be-updated sub-display area comprises:

4. The image processing method according to claim 3, wherein determining the foreground image corresponding to the sub-display area to be updated comprises:

5. The image processing method according to claim 3, wherein determining the foreground image corresponding to the sub-display area to be updated comprises:

selecting a foreground image from the resident foreground images in the memory;

6. The image processing method according to claim 3, wherein the foreground image has a priority;

in the step of superimposing the foreground image on the background image block corresponding to the sub-display area to be updated,

and under the condition that the foreground images corresponding to the sub-display area to be updated are overlapped, at the overlapped position of the foreground images, the non-transparent pixel data of the foreground image with the highest priority is used as the pixel data of the final image block at the corresponding position, and the pixel data of the background image at the overlapped position of the transparent pixels is used as the pixel data of the final image block at the corresponding position.

7. The image processing method according to claim 3, wherein the resolution of the foreground image is smaller than the resolution of the background image.

8. The image processing method according to claim 1, wherein the pixels of the display screen are arranged in an array, the sub-display area is rectangular, and two sides of the rectangle extend in two directions of the array.

9. The image processing method according to claim 1, further comprising:

and under the condition that the display screen needs to be updated into a background image in a full screen mode, transmitting each background image block forming a complete frame of background image in the nonvolatile memory to an output cache block by block, so that the display driving circuit acquires the background image block from the output cache, and replacing pixel data at a corresponding position in a previous frame of image stored by the display driving circuit with pixel data of a corresponding background image block to obtain a new frame of image.

10. An image processing apparatus comprising a memory and a processor, the memory storing instructions that when executed by the processor perform the image processing method of any one of claims 1 to 9.

11. An image processing apparatus characterized by comprising:

the device comprises a first determining module, a second determining module and a display module, wherein the first determining module is used for determining a sub-display area to be updated currently under the condition that part of the display area of the display screen needs to be updated, the display area of the display screen is divided into a plurality of sub-display areas, and any two sub-display areas are not overlapped;

12. The image processing apparatus according to claim 11, further comprising a transparent transmission module, configured to, when the display screen needs to be updated to the background image in a full screen, transparently transmit each background image block constituting a complete frame of background image in the nonvolatile memory to the output buffer block by block, so that the display driving circuit obtains the background image block from the output buffer, and replace the pixel data at the corresponding position in the previous frame of image stored in the background image block with the pixel data of the corresponding background image block to obtain a new frame of image.

13. An electronic device comprising the image processing apparatus according to any one of claims 10 to 12, and comprising a display driving circuit and a display screen driven by the display driving circuit; the display driving circuit is used for storing the previous frame of display data, updating corresponding pixel data in the frame of display data according to the obtained final image block and the corresponding position information, and driving the display screen according to the updated frame of display data.

14. The electronic device of claim 13, wherein the electronic device is a wearable electronic device.