CN107040791B - Adaptive binary image compression method suitable for electronic display labels - Google Patents

Abstract

The present invention provides an adaptive binary image compression method suitable for electronic display labels, including: step 1, comparing the image to be displayed with the current display image to obtain the dot matrix coordinates of the effective refresh area and corresponding update information, the step 2. Perform compression processing on the pattern part and the character part in the update information in two different compression methods. The invention can provide an improved image compression method with high compression efficiency and less resource consumption without increasing the processor resources of the electronic display label. Using the image compression improvement method of the present invention can effectively improve the image transmission response speed of the electronic shelf label, improve the overall work efficiency of the electronic shelf label, not only reduce the time for image refresh transmission, but also effectively save energy consumption and prolong the electronic shelf life. The working life of the label.

Description

Adaptive binary image compression method suitable for electronic display labels

technical field

The invention relates to the field of electronic display, in particular to an adaptive binary image compression method suitable for electronic display labels.

Background technique

At present, there are already many lossless compression methods. The most common algorithms for lossless compression of binary images include swim-length coding, Huffman coding, and LZ77. Based on these algorithms, many people have proposed some optimization algorithms and implemented them through hardware.

However, for the binary image display of electronic shelf labels in the new field, due to the specific characteristics of the image content, the image content of the electronic shelf label is basically fixed in the template of a specific format in practical applications, and the change is usually refreshed locally in a specific area. However, there are not many times when the full screen content is refreshed on the whole screen, but on the contrary, the speed of the transmission response is high. Therefore, in this application field, the commonly used image compression method uses a unified algorithm for the entire screen image to perform uniform and indiscriminate The compression method is actually not suitable and the efficiency is not high. Robin Kuivinen once compared the compression effects of 7 image compression algorithms in electronic shelf labels. The better situation is only about 20%.

The compression for character encoding is also a common image content compression method. Although this method can significantly improve the communication speed and the decompression time is also very short, this method is limited to character content, and it is not suitable for image content. Be applicable. And for most applications, the compression ratio of character encoding is extremely low (full-screen characters even reach about 2%).

After image compression, the smaller the compression rate, the faster the transmission; at the same time, considering the computing and processing capabilities of the electronic display label, the decoding method corresponding to the complex compression algorithm is complicated, and the resource requirements of the label processor for decoding processing are high. However, the processor The higher the resources, the more resource costs will be consumed, which cannot meet the coexistence of high transmission speed and low energy consumption.

Therefore, the current problems include:

1. The common compression algorithm has a low compression rate and is not suitable for the image content of the electronic display label. Complex compression algorithms result in complex decoding methods that place high demands on the label processor.

2. Universal character encoding, although the compression rate is very high and the decompression time is fast, it cannot compress the image, and it is also not suitable for the processing of the content of the electronic display label with both pictures and text.

Therefore, how to find a solution that can adapt to the specific display content of the electronic shelf label and at the same time have a high compression rate is an urgent problem to be solved at present.

Contents of the invention

Aiming at the defects in the prior art, the object of the present invention is to provide an adaptive binary image compression method suitable for electronic display labels.

According to a kind of self-adaptive binary image compression method that is suitable for the electronic display label provided by the present invention, comprises:

Step 1, compare the image to be displayed with the currently displayed image to obtain the lattice coordinates of the effective refresh area and the corresponding update information,

Step 2: Perform compression processing on the pattern part and the character part in the update information by two different compression methods.

Preferably, the method of compressing the pattern part in the update information in the step 2 includes:

Preset a minimum run range and one or more than two consecutive segmented run ranges;

performing run length detection on the pattern portion;

When detecting that the run length of the current data is less than or equal to the minimum run length range, the pattern class transmission data includes an operation flag bit and a data content segment, and the operation flag bit is set to be uncompressed;

When it is detected that the run length of the current data belongs to the segmented run range, the pattern transmission data includes an operation flag bit, a category flag bit, and a data length bit, and the operation flag bit is set to compression, according to the binary value of the current data The attribute determines the category flag bit, and determines the data length bit according to the run length of the current data.

Preferably, when it is detected that the run length of the current data belongs to the segment run range, the length of the reserved data length bit is determined according to the maximum length of the segment run range to which the current data belongs.

Preferably, between said step 1 and step 2, it also includes:

The update information is compared with the character features in the preset character library one by one, and if they match, they will be recognized as the character part, and if they don't match, they will be recognized as the pattern part.

Preferably, the method of compressing the character part in the update information in step 2 includes:

The number corresponding to the character feature matched by the character part in the character library is extracted, and the character class transmission data includes the number and the dot matrix coordinates of the corresponding sequence.

Preferably, the step of presetting the character library is also included before step 1: determining the character feature of each character according to the feature analysis of the character, and storing the character and the character feature corresponding to the character into the character in one-to-one correspondence library and set the numbers sequentially.

Preferably, the characters include Chinese, English, numbers and special characters.

Compared with the prior art, the present invention has the following beneficial effects:

The invention can provide an improved image compression method with high compression efficiency and less resource consumption without increasing the processor resources of the electronic display label. Using the image compression improvement method of the present invention can effectively improve the image transmission response speed of the electronic shelf label, improve the overall work efficiency of the electronic shelf label, not only reduce the time for image refresh transmission, but also effectively save energy consumption and prolong the electronic shelf life. The working life of the label.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without any creative work. In the attached picture:

Fig. 1 is a kind of process steps of adaptive binary image compression method suitable for electronic display labels;

Figure 2 is an example of an image to be displayed;

Figure 3 is an example of the currently displayed image;

Fig. 4 is a data schematic diagram of an uncompressed operation;

Figure 5 is a data schematic diagram of a short compression operation;

Fig. 6 is a data schematic diagram of the compression operation;

Fig. 7 is a data schematic diagram of a long compression operation;

Fig. 8 is a schematic flowchart of an optional method.

Detailed ways

The present invention will be described in detail below in terms of specific embodiments in conjunction with the accompanying drawings. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It is to be noted that other embodiments may be utilized or structural and functional modifications may be made to the embodiments set forth herein without departing from the scope and spirit of the invention.

In an embodiment of an adaptive binary image compression method suitable for electronic display labels provided by the present invention, as shown in FIG. 1 , it includes

According to one provided by the invention, comprising:

Step 1, compare the image to be displayed with the currently displayed image to obtain the lattice coordinates of the effective refresh area and the corresponding update information,

Step 2: Perform compression processing on the pattern part and the character part in the update information by two different compression methods.

The implementation of the run-length algorithm is to replace the consecutive data parts in the string with the current data element and the number of consecutive occurrences of the element. The run in the present invention refers to a section of data in which data elements are repeated, and the length of the run refers to the number of repeated occurrences of the element in the repeated data section. For example, the first run in 1110 is 111 that appears three times, and its run length is 3. The run range means that bits 1-3 are 1 in the range. For details, see the specific examples in the latter part.

As an optional embodiment, the method of compressing the pattern part in the update information in step 2 includes:

Preset a minimum run range and one or more than two consecutive segmented run ranges;

performing run length detection on the pattern portion;

When detecting that the run length of the current data is less than or equal to the minimum run length range, the pattern class transmission data includes an operation flag bit and a data content segment, and the operation flag bit is set to be uncompressed;

When it is detected that the run length of the current data belongs to the segmented run range, the pattern transmission data includes an operation flag bit, a category flag bit, and a data length bit, and the operation flag bit is set to compression, according to the binary value of the current data The attribute determines the category flag bit, and determines the data length bit according to the run length of the current data.

As an optional embodiment, when it is detected that the run length of the current data belongs to the segmented run range, the length of the reserved data length bit is determined according to the maximum length of the segmented run range to which the current data belongs.

As an optional embodiment, the steps between step 1 and step 2 also include:

The update information is compared with the character features in the preset character library one by one, and if they match, they will be recognized as the character part, and if they don't match, they will be recognized as the pattern part.

As an optional embodiment, the method of compressing the character part in the update information in step 2 includes:

The number corresponding to the character feature matched by the character part in the character library is extracted, and the character class transmission data includes the number and the dot matrix coordinates of the corresponding sequence.

As an optional embodiment, the step of presetting the character library is also included before step 1: determining the character features of each character according to the feature analysis of the characters, and making a one-to-one correspondence between the character and the character feature corresponding to the character Store them in the character library and set the numbers in sequence.

As an optional embodiment, the characters include Chinese, English, numbers, and special characters.

The above scheme can also be implemented through the following scheme process, and the method includes the following steps:

1. Automatically identify and refresh content

Scan the full-screen dot matrix image, compare and convert it with the current image content, get the changed area, and lock the coordinates of the effective refresh area that needs to be refreshed.

2. Automatic recognition of electronic display label images and characters

Compare the content of the effective refresh area with the character characteristics of the font library one by one, and the character content can be automatically identified if the comparison is successful.

The area that cannot be matched with font characters is defined as the image content.

3. Use different compression engines to process image content and character content:

For image content, an optimized run length determination compression coding algorithm with low memory usage and low compression rate is adopted.

For character content, the character encoding method is used for image compression.

4. The terminal label receives the transmitted content and automatically adapts to decode and refresh the corresponding content in the corresponding area:

The transmission protocol adopts the method of separate transmission of characters and images

The terminal label receives the data packet of character characteristics, directly starts the pre-stored character encoding table, and after reading the coordinate information, refreshes the code reading display of the character content.

The terminal label receives the data packet of image characteristics, starts the image decoding engine, determines the compression encoding method according to the run length determined by the protocol, determines which method to decode the image content, and decodes and displays the decoded image content according to the coordinate information. Refresh.

Specific embodiment example:

As shown in Figures 2 and 3, Figure 2 is the image to be displayed, and Figure 1 on the right is the currently displayed image.

Step 1. Automatically identify and refresh content.

1. Use the image engine to scan and compare image 1 and image 2

2. Calculate the difference between the text 5 and the image 3. The coordinates of the locked text 5 and image 3 are:

Text 5 start coordinates = (X1, Y1), text 5 end coordinates = (X2, Y2);

Image 3 start coordinates=(X3, Y3), image 3 end coordinates=(X4, Y4);

Step 2. The method of automatically identifying the image and characters of the electronic display label:

1. Perform feature analysis on the characters in the font library in advance, and store the features of each character,

2. The content locked in operation comparison step 1 is calculated and compared with the character features. If the comparison of text 5 is successful, it is locked as character content. If the content of image 3 is not successfully compared, it is defined as image content.

3. It has been confirmed by comparison that the content code word field encoding of text 5 is expressed as (W1..Wn)

3. Send the text 5-field code and text map coordinates to the text compression processing engine for character compression processing

4. Send the image 3 coordinate range content to the pattern compression processing engine for data processing

Step 3, character compression processing engine: adopt the compression mode of the present invention to design prestored character encoding table to character content:

The electronic display label of the present invention has pre-stored the font character encoding table, and in actual use, the characters must first be encoded and stored in the flash. The font library mainly includes Chinese, English, numbers, special characters, etc.

Recognize the character content, after entering the character compression engine, for the character encoding, the information after compression only includes the character position coordinates. W1..Wn).

Step 3, pattern compression processing engine: adopt the optimized run length judgment compression encoding designed by the present invention to pattern content:

When the run length is not greater than the minimum run length range 7, the information is not compressed, and it is determined that the content of the information itself is very small and does not need to be compressed. The content of the pattern transmission data is shown in Figure 4.

When the run length is greater than 256, the long compression method shown in Figure 7 will be used.

When the run length is greater than 64 and less than 256, the medium compression method shown in Figure 6 will be used.

When the run length is greater than 7 and less than 64, the short compression method shown in Figure 5 will be used.

For non-compressed operation, the first bit is 1 to indicate no compression, and the remaining 7 bits represent image pixel information.

For short compression, the first bit is 0 to indicate compression, and the second bit indicates the specific content of the subsequent repeated pixels. If it is 1, the subsequent pixels are all black; if it is 0, the subsequent pixels are all white. The remaining 6 bits represent the run length.

For medium compression and long compression, the first byte is the information byte, the first bit 0 indicates compression, and the second bit indicates the specific content of subsequent repeated pixels. The last 6 bits represent long compression or medium compression.

For long compression, the following 2 bytes represent the run length; for medium compression, the following 1 byte represents the run length.

Suppose the 3 pixel information of the image is as follows, 0 means white, 1 means black:

00000001111...1111000...000111...111

8 consecutive white pixels, 60 consecutive black pixels, 80 consecutive white pixels, 257 consecutive black pixels

For image 3, after entering the pattern compression engine. The number of repeated pixels is counted from the start position, which is defined as the run length.

The calculation results in that the content of the first repeated pixel of image 3 is 0, and the length of the run is L=7, and L is not greater than the minimum run range 7 without compression. Compression processing is not performed on this part of the content, and the subsequent continuous 7 bits are selected to directly transmit the pixel content . Then the content of this part is expressed in 8bits after compression:

10000000

Then, enter the next part of repeated pixel statistics, the repeated pixel content is 1, and the run length L=60 is obtained from the statistics. L exceeds the non-compressed minimum run length range of 7, and is less than 64. Short compression is performed on this part of the content, and it is represented by an 8bits after compression

More than 64 and less than 256, for this part of the content, use medium compression encoding:

01111100

Then, enter the next part of repeated pixel statistics, the repeated pixel content is 0, and the run length L=80 is obtained from the statistics. L exceeds the uncompressed minimum run range 7,

More than 64 and less than 256, for this part of the content, use the medium compression method to encode, and use 16bits to express after compression:

00000000 01010000

Then, enter the next part of repeated pixel statistics, the repeated pixel content is 1, and the run length L=257 is obtained from statistics. L is greater than 256. For this part of the content, the long compression method is used to encode it, and it is represented by 24 bits after compression:

01000001 00000001 00000001

Step 4. Decompress the terminal label and refresh to display the new image 2.

The terminal label receives the information corresponding to the character 5, including the character code table number (W1..Wn), and searches for the coordinates of the character code in f1ash, (f1..fn), and the decoding is successful, and the initial coordinate of the character 5=( X1, Y1), the coordinates of the end point of text 5 = (X2, Y2); the area is directly read (f1..fn), and the font flash pixels of the table number are partially refreshed and displayed.

The terminal tag receives the encoded content of image 3 and decodes it. Starting coordinates of image 3 = (X3, Y3), end coordinates of image 3 = (X4, Y4); after decoding, refresh the following content.

First judge the first bit, if it is 1, then it is judged that the 8 bits are uncompressed content, and the remaining 7 bits are pixel content, and 7 white pixels are continuously displayed.

Then, it is judged that the first bit of the next byte is 0, then the subsequent content is compressed. If the second bit is 1, the subsequent repeated pixel content is a black pixel. Then read the subsequent 6 bits, if it is greater than 2, then only the The 6 bits represent the length of the run length. The six bits are 111100, and it is decoded as a run length of 60. Continuously display 60 black pixels.

Then, it is judged that the first bit of the next byte is 0, then the subsequent is the compressed content. If the second bit is 0, the subsequent repeated pixel content is a white pixel. Then read the next 6 bits, 000000, it means the byte The last 8bits is the run length. That is, 01010000, it is decoded as a run length of 80. Continuously display 80 white pixels.

Then, it is judged that the first bit of the next byte is 0, then the subsequent content is compressed. If the second bit is 1, the subsequent repeated pixel content is a black pixel. Then read the next 6 bits, 000001, which means the byte The last 16bits is the run length. That is, 00000001 00000001, it is decoded as a run length of 257. Continuously display 257 white pixels.

The invention can provide an improved image compression method with high compression efficiency and less resource consumption without increasing the processor resources of the electronic display label.

The improved image compression method of the present invention can automatically identify image content and character content without manual intervention.

Using the image compression improvement method of the present invention can effectively improve the image transmission response speed of the electronic shelf label, improve the overall work efficiency of the electronic shelf label, not only reduce the time for image refresh transmission, but also effectively save energy consumption and prolong the electronic shelf life. The working life of the label.

The above descriptions are only preferred embodiments of the present invention, and those skilled in the art know that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, the features and examples may be modified to adapt a particular situation and material to the teachings of the invention without departing from the spirit and scope of the invention. Therefore, the present invention is not limited by the specific embodiments disclosed here, and all embodiments falling within the scope of the claims of the present application belong to the protection scope of the present invention.

Claims (6)

1. An adaptive binary image compression method suitable for electronic display labels, characterized in that, comprising: Step 1, compare the image to be displayed with the currently displayed image to obtain the lattice coordinates of the effective refresh area and the corresponding update information; Comparing the update information with the character features in the preset character library one by one, if they match, they will be recognized as character parts, if they don’t match, they will be recognized as pattern parts; Step 2, respectively compressing the pattern part and the character part in the update information by two different compression methods; the pattern part adopts the optimized run length judgment compression coding; the character part adopts the compression method of the pre-stored character code table . 2. A kind of self-adaptive binary image compression method suitable for electronic display labels according to claim 1, characterized in that the compression method of the pattern part in the update information in the step 2 comprises: Preset a minimum run range and one or more than two consecutive segmented run ranges; performing run length detection on the pattern portion; When detecting that the run length of the current data is less than or equal to the minimum run length range, the pattern class transmission data includes an operation flag bit and a data content segment, and the operation flag bit is set to be uncompressed; When it is detected that the run length of the current data belongs to the segmented run range, the pattern transmission data includes an operation flag bit, a category flag bit, and a data length bit, and the operation flag bit is set to compression, according to the binary value of the current data The attribute determines the category flag bit, and determines the data length bit according to the run length of the current data. 3. A kind of self-adaptive binary image compression method suitable for electronic display labels according to claim 2, characterized in that, when it is detected that the run length of the current data belongs to the segment run range, according to the current data belongs to The maximum length of the segmented run range determines the length of bits reserved for the data length. 4. A kind of adaptive binary image compression method suitable for electronic display labels according to claim 1, characterized in that, the compression method of the character part in the update information in the step 2 comprises: The number corresponding to the character feature matched by the character part in the character library is extracted, and the character class transmission data includes the number and the dot matrix coordinates of the corresponding sequence. 5. A kind of self-adaptive binary image compression method suitable for electronic display labels according to claim 1, characterized in that, before step 1, also includes the step of preset character library: determine each The character features of a character, the character and the character feature corresponding to the character are stored in the character library in one-to-one correspondence, and the numbers are set in sequence. 6. An adaptive binary image compression method suitable for electronic display labels according to claim 1, wherein the characters include Chinese, English, numbers and special characters.