CN108921784B - Picture compression method and system based on mobile terminal - Google Patents

Abstract

The invention discloses a picture compression method and system based on a mobile terminal, comprising the steps of: S11. Obtaining the resolution of the mobile terminal itself and the picture resolution; S12. Judging whether the picture is long or not according to the resolution of the picture Picture; if so, then jump to step S13, if not, then jump to step S14; S13. Calculate the zoom rate of the picture according to the long picture zoom rate calculation method, and then jump to step S15; S14. Calculate according to the conventional picture zoom rate The method calculates the zoom ratio of the picture, and then jumps to step S15; S15. calculates the sampling rate of the picture according to the calculated zoom ratio of the picture; S16. judges whether the picture needs to be compressed; if so, jumps to step S17; S17 . Compress the picture according to the size of the sampling rate. The present invention avoids the OOM problem caused by picture display and at the same time optimizes the display effect of the compressed picture on the mobile phone.

Description

A mobile terminal-based picture compression method and system

technical field

The present invention relates to the technical field of image processing, in particular to a mobile terminal-based image compression method and system.

Background technique

With the advancement of technology, the performance of the mobile terminal has also been greatly improved, and at the same time, there are more and more pictures in the mobile terminal. Wherein, the source of the picture may include various aspects, such as a user's photo, a webpage picture, a picture generated by social software, and the like. As the number of pictures increases, a large amount of storage space of the mobile terminal will be occupied, and an OOM (Out of Memory, memory overflow) problem often occurs in the mobile terminal.

Image display can be said to be unavoidable in any application software. However, loading and displaying large images on Android phones often causes OOM problems. The reason is that ImageView (image view) on Android devices will eventually load Bitmap (bitmap files) Object, the memory occupied by Bitmap is too large.

Bitmap memory size = picture width * picture height * byte occupied by unit pixel; the byte occupied by unit pixel is related to the encoding of Bitmap, as shown in the following table:

Bitmap encoding The number of bytes occupied by a unit pixel ALPHA_8 1 ARGB_4444 2 ARGB_8888 4 RGB_565 2

Usually the android system uses ARGB_8888 encoding, so the memory usage of a common 1080*1920 picture is: 1920*1080*4=7.9M.

It can be seen from the above formula that the memory occupied by the compressed image needs to start with the image size (width and height) and Bitmap encoding.

Android officially provides a sampling rate compression method. By setting the sampling rate inSampleSize (this sampling rate can only be 2 to the Nth power, if the calculated sampling rate is 5, the Android system will approximate the value 4), to compress the image, so that Its size becomes smaller, so as to achieve the effect of reducing the memory occupied by pictures.

However, the sampling rate of the sampling rate compression method can only be 2 to the Nth power (1, 2, 4, 8...), if you need to compress a picture with a resolution of 3840*2400 to the current mobile phone resolution of 1280*720 After calculating the sampling rate inSampleSize is max(3840/1280, 2400/720)=3.33, that is, the ideal compressed size should be (3840*2400)/3.33=1152*720, but the system will correct the ideal sampling rate 3.33 to 2^2=4, so the resolution of the picture compressed by the sampling compression algorithm can only be 960*600, so the size of the compressed picture does not meet the expected picture size, and for long pictures, the sampling rate compression method, Images are often over-compressed, that is, the size of the compressed image will be very small, which will affect the display effect of the image.

The patent with the publication number CN 201360283 discloses a device for compressing and storing pictures in mobile phones, including: a mobile phone CPU, a decompression module, compressed picture resource data and a display module. By adding a picture decompression module in the mobile phone, When using compressed image resources, the compressed image resource data is decompressed first, and then displayed by the display module. Thereby, the occupation of the storage space by the image resource is reduced, and the storage cost of the mobile phone is greatly reduced. Although this method can realize the compression of pictures in the mobile phone, the same compression rules are used for regular pictures and long pictures when compressing pictures, and excessive compression of long pictures cannot be avoided, thereby affecting the display effect of long pictures.

Contents of the invention

The object of the present invention is to address the defects of the prior art, and provide a mobile terminal-based picture compression method and system, which uses different algorithms to calculate the scaling ratio and picture compression ratio for regular pictures and long pictures according to the current mobile terminal resolution. Target size to compress pictures, avoiding OOM problems caused by picture display, and at the same time make the compressed pictures display best on this phone.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for image compression based on a mobile terminal, comprising the steps of:

S1. Obtain the resolution of the mobile terminal itself and the resolution of the picture;

S2. Judging whether the picture is a long picture according to the resolution of the picture; if so, then jump to step S3, if not, then jump to step S4;

S3. Calculate the zoom rate of the picture according to the calculation method of the zoom rate of the long picture, and then skip to step S5;

S4. Calculate the zoom rate of the picture according to the conventional picture zoom rate calculation method, and then skip to step S5;

S5. Calculate the sampling rate of the picture according to the zoom rate of the calculated picture;

S6. Determine whether the picture needs to be compressed; if so, skip to step S7;

S7. Compress the picture according to the size of the sampling rate.

Further, after the step S7, the step also includes:

S8. Determine whether the size of the compressed picture is consistent with the size of the target picture, if not, then skip to step S9;

S9. Perform Matrix scaling processing on the compressed picture so that the final size of the picture is the target size.

Further, the specific method for judging whether the picture is a long picture according to the resolution of the picture is as follows:

Calculate the ratio of the height and width of the image according to the resolution of the image;

Judging whether the ratio is greater than 2, if yes, the picture is a long picture.

Further, the method for calculating the scaling ratio of the long image is:

A1. Calculate the total number of pixels on the screen of the mobile terminal itself;

A2. Calculate the total number of pixels in the long image;

A3. Calculate the zoom ratio of the long image according to the total number of pixels of the mobile terminal's own screen and the total number of pixels of the long image.

Further, the calculation method of the conventional image scaling ratio is:

B1. Calculate the ratio of the picture width to the screen width of the mobile terminal itself;

B2. Calculate the ratio of the height of the picture to the height of the screen of the mobile terminal itself;

B3. Taking the larger of the ratio of the width and the ratio of the height as the zoom ratio of the picture.

Further, the size calculation method of the target picture is:

The width of the target picture is the width of the picture divided by the calculated zoom rate of the picture; the height of the target picture is the height of the picture divided by the calculated zoom rate of the picture value.

Correspondingly, a mobile terminal-based picture compression system is also provided, including:

An acquisition module, configured to acquire the resolution of the mobile terminal itself and the resolution of the picture;

A first judging module, configured to judge whether the picture is a long picture according to the resolution of the picture;

The first calculation module is used to calculate the zoom rate of the picture according to the long picture zoom rate calculation method when the picture is a long picture;

The second calculation module is used to calculate the zoom rate of the picture according to the conventional picture zoom rate calculation method when the picture is a non-long picture;

The third calculation module is used to calculate the sampling rate of the picture according to the zoom rate of the calculated picture;

The second judging module is used to judge whether the picture needs to be compressed;

The compression module is configured to compress the picture according to the size of the sampling rate when the picture needs to be compressed.

Further, it also includes:

The third judging module is used to judge whether the size of the compressed picture is consistent with the size of the target picture;

A scaling module, configured to perform Matrix scaling on the compressed picture when the size of the compressed picture is inconsistent with the size of the target picture so that the final size of the picture is the target size.

Further, the specific method for judging whether the picture is a long picture according to the resolution of the picture is as follows:

Calculate the ratio of the height and width of the image according to the resolution of the image;

Judging whether the ratio is greater than 2, if yes, the picture is a long picture.

Further, the method for calculating the scaling ratio of the long image is:

A1. Calculate the total number of pixels on the screen of the mobile terminal itself;

A2. Calculate the total number of pixels in the long image;

A3. Calculate the zoom ratio of the long image according to the total number of pixels of the mobile terminal's own screen and the total number of pixels of the long image.

Further, the calculation method of the conventional image scaling ratio is:

B1. Calculate the ratio of the picture width to the screen width of the mobile terminal itself;

B2. Calculate the ratio of the height of the picture to the height of the screen of the mobile terminal itself;

B3. Taking the larger of the ratio of the width and the ratio of the height as the zoom ratio of the picture.

Further, the size calculation method of the target picture is:

The width of the target picture is the width of the picture divided by the calculated zoom rate of the picture; the height of the target picture is the height of the picture divided by the calculated zoom rate of the picture value.

Compared with the prior art, the present invention determines the target size of the picture according to the resolution of the current mobile terminal, calculates the zoom rate and target picture size by using different algorithms for conventional pictures and long pictures, and then obtains the zoom rate through the calculation. Obtain the sampling rate, and then compress the picture according to the sampling rate, which can avoid OOM problems when the picture is displayed on the mobile terminal, and can effectively prevent long pictures from being over-compressed, and judge whether the compressed picture size is consistent with the target size after compression. If the size of the compressed image is inconsistent with the target size, scale the image through Matrix to make the image size meet the target size, so that the final image can be displayed on the mobile terminal with the best effect.

Description of drawings

FIG. 1 is a flow chart of a mobile terminal-based image compression method provided in Embodiment 1;

FIG. 2 is a structural diagram of a mobile terminal-based picture compression system provided by Embodiment 1;

FIG. 3 is a flow chart of a mobile terminal-based picture compression method provided in Embodiment 2;

FIG. 4 is a structural diagram of a mobile terminal-based picture compression system provided by Embodiment 2.

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the case of no conflict, the following embodiments and features in the embodiments can be combined with each other.

It should be noted that the diagrams provided in the following embodiments are only schematically illustrating the basic ideas of the present invention, and only the components related to the present invention are shown in the diagrams rather than the number, shape and shape of the components in actual implementation. Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

The present invention provides a mobile terminal-based picture compression method and system. According to the current mobile terminal resolution, different algorithms are used to calculate the zoom rate and the target size of picture compression for regular pictures and long pictures to compress pictures, so as to avoid picture display While causing the OOM problem, the compressed picture can be displayed on the mobile phone with the best effect.

Embodiment one

This embodiment provides a mobile terminal-based picture compression method, as shown in Figure 1, including steps:

S11. Obtain the resolution of the mobile terminal itself and the resolution of the picture;

S12. Judging whether the picture is a long picture according to the resolution of the picture; if so, then jump to step S13, if not, then jump to step S14;

S13. Calculate the zoom rate of the picture according to the calculation method of the zoom rate of the long picture, and then skip to step S15;

S14. Calculate the zoom rate of the picture according to the conventional picture zoom rate calculation method, and then skip to step S15;

S15. Calculate the sampling rate of the picture according to the calculated zoom rate of the picture;

S16. Determine whether the picture needs to be compressed; if so, skip to step S17;

S17. Compress the picture according to the size of the sampling rate.

The mobile terminal-based image compression method in this embodiment is executed by the mobile terminal. Specifically, the mobile terminal is an Android system.

First, the mobile terminal will obtain its own resolution (width is W, height is H) and the resolution of the picture (width is W1, height is H1), so as to calculate the subsequent scaling ratio.

After the resolution of the picture is obtained, it can be judged whether the picture is a long picture according to the resolution of the picture. If the picture is a long picture, the zoom rate calculation method of the long picture is used to calculate the zoom rate of the picture. If the picture is not a long picture ( That is, the conventional picture) calculates the zoom ratio of the picture by using the conventional picture zoom ratio calculation method.

Further, the specific method for judging whether the picture is a long picture according to the resolution of the picture is as follows:

Calculate the ratio of the height and width of the image according to the resolution of the image;

Judging whether the ratio is greater than 2, if yes, the picture is a long picture.

Specifically, the resolution of the picture obtained above (width is W1, height is H1), if the value of H1/W1 is greater than 2, the picture is a long picture, otherwise, the picture is a regular picture.

Further, the method for calculating the scaling ratio of the long image is:

A1. Calculate the total number of pixels on the screen of the mobile terminal itself;

A2. Calculate the total number of pixels in the long image;

A3. Calculate the zoom ratio of the long image according to the total number of pixels of the mobile terminal's own screen and the total number of pixels of the long image.

Specifically, according to the resolution of the mobile terminal (the width is W, the height is H) the total number of pixels of the mobile terminal screen P=W*H can be obtained; according to the resolution of the picture (the width is W1, the height is H1) Just can obtain the total number of pixels of the picture P1=W1*H1; Then just can calculate the zoom rate of this long picture according to the total number of pixels of the screen of the mobile terminal itself and the total number of pixels of the long picture, specific zoom ratio In this embodiment, the scaling ratio of the long picture is divided into the square root of the ratio of the total pixels to make the scaling ratio of the long picture smaller than that of the conventional picture, thereby avoiding excessive compression of the long picture.

Further, the calculation method of the conventional image scaling ratio is:

B1. Calculate the ratio of the picture width to the screen width of the mobile terminal itself;

B2. Calculate the ratio of the height of the picture to the height of the screen of the mobile terminal itself;

B3. Taking the larger of the ratio of the width and the ratio of the height as the zoom ratio of the picture.

Specifically, according to the resolution of the mobile terminal (the width is W, the height is H) and the resolution of the picture (the width is W1, the height is H1), first calculate the ratio rw=W1/W of the picture width and the screen width of the mobile terminal itself, Then calculate the ratio rh=H1/H between the height of the picture and the height of the mobile terminal's own screen, and finally take the larger one of rw and rh as the scaling ratio ratio of the picture.

The zoom rate of the picture can be calculated by the above-mentioned long picture zoom rate calculation method and the conventional picture zoom rate calculation method. After calculating the zoom rate of the picture, the sampling rate of the picture can be obtained. In this embodiment, the value of the sampling rate inSampieSize It is the closest Nth power value of 2 to the zoom ratio ratio. For example, if the zoom ratio is 2.8, then the sampling rate is 2; if the zoom ratio is 3.3, then the sampling rate is 4.

After calculating the sampling rate, it is necessary to judge whether the picture needs to be compressed. Specifically, if the sampling rate is greater than 1, the picture will be compressed according to the size of the sampling rate. If the sampling rate is less than or equal to 1, the picture will not be compressed.

Correspondingly, this embodiment also provides a mobile terminal-based image compression system, as shown in FIG. 2 , including:

Obtaining module 11, is used for obtaining the resolution of mobile terminal self and the resolution of picture;

The first judging module 12 is used to judge whether the picture is a long picture according to the resolution of the picture;

The first calculation module 13 is used to calculate the zoom rate of the picture according to the long picture zoom rate calculation method when the picture is a long picture;

The second calculation module 14 is used to calculate the zoom rate of the picture according to the conventional picture zoom rate calculation method when the picture is a non-long picture;

The third calculation module 15 is used to calculate the sampling rate of the picture according to the calculated zoom rate of the picture;

The second judging module 16 is used to judge whether the picture needs to be compressed;

The compression module 17 is configured to compress the picture according to the size of the sampling rate when the picture needs to be compressed.

Specifically, the specific method for judging whether the picture is a long picture according to the resolution of the picture is as follows:

Calculate the ratio of the height and width of the image according to the resolution of the image;

Judging whether the ratio is greater than 2, if yes, the picture is a long picture.

Specifically, the method for calculating the zoom ratio of the long image is:

A1. Calculate the total number of pixels on the screen of the mobile terminal itself;

A2. Calculate the total number of pixels in the long image;

A3. Calculate the zoom ratio of the long image according to the total number of pixels of the mobile terminal's own screen and the total number of pixels of the long image.

Specifically, the calculation method of the conventional image scaling ratio is:

B1. Calculate the ratio of the picture width to the screen width of the mobile terminal itself;

B2. Calculate the ratio of the height of the picture to the height of the screen of the mobile terminal itself;

B3. Taking the larger of the ratio of the width and the ratio of the height as the zoom ratio of the picture.

In this embodiment, different algorithms are used to calculate the zoom rate and target picture size of conventional pictures and long pictures, and then the sampling rate is obtained through the calculated scaling rate, and then the pictures are compressed according to the sampling rate, which can avoid the display of pictures in the mobile terminal. The OOM problem can effectively prevent long pictures from being over-compressed.

Embodiment two

This embodiment provides a mobile terminal-based image compression method, as shown in FIG. 3 , including steps:

S21. Obtain the resolution of the mobile terminal itself and the resolution of the picture;

S22. Judging whether the picture is a long picture according to the resolution of the picture; if so, then jump to step S23, if not, then jump to step S24;

S23. Calculate the zoom rate of the picture according to the calculation method of the zoom rate of the long picture, and then skip to step S25;

S24. Calculate the zoom rate of the picture according to the conventional picture zoom rate calculation method, and then skip to step S25;

S25. Calculate the sampling rate of the picture according to the calculated zoom rate of the picture;

S26. Determine whether the picture needs to be compressed; if so, skip to step S27;

S27. Compress the picture according to the size of the sampling rate;

S28. Determine whether the size of the compressed picture is consistent with the size of the target picture, if not, skip to step S29;

S29. Perform Matrix scaling processing on the compressed picture so that the final size of the picture is the target size.

The difference from the first embodiment is that this embodiment further includes step S28 and step S29, and the rest of the steps are the same as those of the first embodiment, and will not be repeated here.

In this embodiment, after the picture is compressed according to the sampling rate, it is judged whether the size of the compressed picture is consistent with the size of the target picture. If the size of the compressed picture is inconsistent with the size of the target picture, then the compressed picture Perform Matrix zoom processing to make the size of the picture consistent with the size of the target picture, so that the final picture will have the best display effect on the mobile terminal.

Specifically, the method for calculating the size of the target image is:

The width of the target picture is the width of the picture divided by the calculated zoom rate of the picture; the height of the target picture is the height of the picture divided by the calculated zoom rate of the picture value.

Below in conjunction with example this embodiment is described in detail:

(1) The resolution of the original picture is 4032*3024, and the size is 2.35M. Because 4032/3024 is less than 2, the picture is a regular picture. Assume that the current mobile terminal resolution is 1920*1080. According to the calculation method of the conventional picture scaling ratio, it can be Get rh=4032/1920=2.1, rw=3024/1080=2.8, scaling ratio=max(rh,rw)=2.8, target picture size W2=4032/2.8=1440, H2=3024/2.8=1080. The sampling rate inSampleSize=2 is obtained according to the "algorithm for calculating the sampling rate". The image size after sampling and compression is 2016*1512 and the target size is 1440*1080, and then the final size of the image is the target size of 1440*1080 through Matrix scaling, and the output compressed image has a size of 1440*1080 and a size of 140.8K , here select 3 mobile terminals with different resolutions to execute the solution of this embodiment, and the results are shown in the following table:

mobile terminal resolution 1920*1080 1280*720 540*360 target image resolution 1440*1080 960*720 480*360 Resolution after sample compression 2016*1512 1008*756 504*378 Matrix scaled resolution 1440*1080 960*720 480*360 Image size after compression 140.8k 60.2k 21k

(2) The resolution of the original picture is 6750*1346, and the size is 5.18M. Because 6750/1346 is greater than 2, the picture is a long picture. Assume that the current mobile terminal resolution is 1920*1080. Yes" get P = 1920*1080 = 2073600, P1 = 6750*1346 = 9088550, scaling Target picture size W2=6750/2.1=3214, H2=1346/2.1=640. The sampling rate inSampleSize=2 is obtained according to the "algorithm for calculating the sampling rate". The image size after sampling and compression is 3375*673 and the target size is 3214*640, and then the final size of the image is 3214*640 through Matrix scaling, and the output compressed image has a size of 3214*640 and a size of 140.8K . Here, 3 mobile terminals with different resolutions are selected to execute the solution of this embodiment, and the results are shown in the following table:

mobile terminal resolution 1920*1080 1280*720 540*360 target image resolution 3214*640 2150*482 990*197 Resolution after sample compression 3375*673 1687*336 844*168 Matrix scaled resolution 3214*640 2150*482 990*197 Image size after compression 414.6k 283.2k 56.7k

Correspondingly, this embodiment also provides a mobile terminal-based image compression system, as shown in FIG. 4 , including:

Obtaining module 21, used to obtain the resolution of the mobile terminal itself and the resolution of the picture;

The first judging module 22 is configured to judge whether the picture is a long picture according to the resolution of the picture;

The first calculation module 23 is used to calculate the zoom rate of the picture according to the long picture zoom rate calculation method when the picture is a long picture;

The second calculation module 24 is used to calculate the zoom rate of the picture according to the conventional picture zoom rate calculation method when the picture is a non-long picture;

The third calculation module 25 is used to calculate the sampling rate of the picture according to the zoom rate of the calculated picture;

The second judging module 26 is used to judge whether the picture needs to be compressed;

The compression module 27 is configured to compress the picture according to the size of the sampling rate when the picture needs to be compressed.

The third judging module 28 is used to judge whether the size of the compressed picture is consistent with the size of the target picture;

The scaling module 29 is configured to perform Matrix scaling processing on the compressed picture when the size of the compressed picture is inconsistent with the size of the target picture so that the final size of the picture is the target size.

Specifically, the method for calculating the size of the target image is:

The width of the target picture is the width of the picture divided by the calculated zoom rate of the picture; the height of the target picture is the height of the picture divided by the calculated zoom rate of the picture value.

In this embodiment, different algorithms are used to calculate the zoom rate and target picture size of conventional pictures and long pictures, and then the sampling rate is obtained through the calculated scaling rate, and then the pictures are compressed according to the sampling rate, which can avoid the display of pictures in the mobile terminal. The OOM problem can effectively avoid excessive compression of long pictures, and after compression, it is also judged whether the size of the compressed picture is consistent with the target size. If the size of the compressed picture is inconsistent with the target size, the picture is scaled by Matrix to make the picture size Meet the target size, so that the final picture can display the best effect on the mobile terminal.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention, and the present invention The scope is determined by the scope of the appended claims.

Claims (8)

1. The picture compression method based on the mobile terminal is characterized by comprising the following steps:

s1, acquiring the resolution of a mobile terminal and the resolution of a picture;

s2, judging whether the picture is a long picture or not according to the resolution ratio of the picture; if yes, jumping to the step S3, and if not, jumping to the step S4;

s3, calculating the scaling rate of the picture according to a long-picture scaling rate calculation method, and then jumping to the step S5;

s4, calculating the scaling rate of the picture according to a conventional picture scaling rate calculation method, and then jumping to the step S5;

s5, calculating the sampling rate of the picture according to the calculated scaling rate of the picture;

s6, judging whether the picture needs to be compressed or not; if yes, jumping to the step S7;

s7, compressing the picture according to the sampling rate;

the specific method for judging whether the picture is a long picture according to the resolution ratio of the picture comprises the following steps:

calculating the ratio of the height to the width of the picture according to the resolution ratio of the picture;

judging whether the ratio is greater than 2, if so, the picture is a long picture;

the method for calculating the long graph scaling rate comprises the following steps:

A1. calculating the total number of pixel points of a screen of the mobile terminal;

A2. calculating the total pixel number of the long graph;

A3. and taking the result of opening the root number according to the ratio of the total pixel number of the screen of the mobile terminal to the total pixel number of the long graph as the scaling rate of the long graph.

2. The mobile terminal-based picture compression method according to claim 1, wherein the step S7 further comprises the steps of:

s8, judging whether the size of the compressed picture is consistent with the size of the target picture, if not, jumping to the step S9;

s9, performing Matrix scaling treatment on the compressed picture to enable the final size of the picture to be the target size.

3. The mobile terminal-based picture compression method according to claim 1, wherein the conventional picture scaling rate calculation method is as follows:

B1. calculating the ratio of the picture width to the screen width of the mobile terminal;

B2. calculating the ratio of the picture height to the screen height of the mobile terminal;

B3. taking the larger of the ratio of the width and the ratio of the height as the scaling rate of the picture.

4. The picture compression method based on the mobile terminal as claimed in claim 2, wherein the size calculation method of the target picture is as follows:

the width of the target picture is the value of dividing the width of the picture by the calculated scaling rate of the picture; the height of the target picture is the value of the height of the picture divided by the calculated scaling rate of the picture.

5. A mobile terminal-based picture compression system, comprising:

the acquisition module is used for acquiring the resolution of the mobile terminal and the resolution of the picture;

the first judging module is used for judging whether the picture is a long picture or not according to the resolution ratio of the picture;

the first calculation module is used for calculating the scaling rate of the picture according to a long picture scaling rate calculation method when the picture is a long picture;

the second calculation module is used for calculating the scaling rate of the picture according to a conventional picture scaling rate calculation method when the picture is a non-long picture;

the third calculation module is used for calculating the sampling rate of the picture according to the calculated scaling rate of the picture;

the second judging module is used for judging whether the picture needs to be compressed or not;

the compression module is used for compressing the picture according to the size of the sampling rate when the picture needs to be compressed;

the specific method for judging whether the picture is a long picture according to the resolution ratio of the picture comprises the following steps:

calculating the ratio of the height to the width of the picture according to the resolution ratio of the picture;

judging whether the ratio is greater than 2, if so, the picture is a long picture;

the method for calculating the long graph scaling rate comprises the following steps:

A1. calculating the total number of pixel points of a screen of the mobile terminal;

A2. calculating the total pixel number of the long graph;

A3. and taking the result of opening the root number according to the ratio of the total pixel number of the screen of the mobile terminal to the total pixel number of the long graph as the scaling rate of the long graph.

6. The mobile terminal-based picture compression system of claim 5, further comprising:

the third judging module is used for judging whether the size of the compressed picture is consistent with the size of the target picture or not; and the scaling module is used for performing Matrix scaling processing on the compressed picture to enable the final size of the picture to be the target size when the size of the compressed picture is inconsistent with the size of the target picture.

7. The mobile terminal-based picture compression system of claim 5, wherein the conventional picture scaling calculation method is as follows:

B1. calculating the ratio of the picture width to the screen width of the mobile terminal;

B2. calculating the ratio of the picture height to the screen height of the mobile terminal;

B3. taking the larger of the ratio of the width and the ratio of the height as the scaling rate of the picture.

8. The mobile terminal-based picture compression system according to claim 6, wherein the size calculation method of the target picture is as follows:

the width of the target picture is the value of dividing the width of the picture by the calculated scaling rate of the picture; the height of the target picture is the value of the height of the picture divided by the calculated scaling rate of the picture.