Method for compressing and decompressing single picture

A compression method, a single image technology, applied in image communication, color TV with pulse code modulation, television, etc., can solve problems such as slow compression, high frequency component attenuation, JPEG2000 blurring and distortion, etc.

Active Publication Date: 2013-04-03
京北方信息技术股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] Because the JPEG algorithm divides the image into blocks, it produces serious mosaic distortion, that is, the block effect at a high compression ratio. Some sudden changes in the structure, such as edge information is far more important than image stationarity, using the cosine base as a nonlinear approximation of the image signal, the result is not optimal
[0009] The JPEG2000 algorithm is complex, and the compression speed is slow for large-size images; under medium and low compression ratios, the advantages of JPEG2000 are not obvious; in addition, JPEG2000 has fuzzy distortion, which is mainly caused by a certain degree of high-frequency components in the encoding process. attenuation of
[0010] JBIG is mainly aimed at binary images, and it is difficult to compress color and grayscale images
[0011] JPEG and JPEG2000 compression algorithms are suitable for a variety of images, including grayscale images and color images, and are universal, so the cost is that the algorithm is complex and sacrifices a certain speed
When using a high compression ratio to compress large-scale scanned grayscale images, the above algorithms have the disadvantages of poor compression quality and slow speed, respectively.

Method used

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  • Method for compressing and decompressing single picture
  • Method for compressing and decompressing single picture
  • Method for compressing and decompressing single picture

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0130] Create at least one flag array, divide the pixels of the scanned image into N categories according to a preset method and store them in at least two arrays, and record the storage position of each pixel in the flag array.

[0131] The specific recording method of the flag array depends on the specific situation, and the principle is to save storage space. For example, if it is divided into two categories, a BOOL array can be used to sequentially store the classification positions of each pixel. For example, if the i-th element of the array is 0, it means that the i-th pixel in the scanned image is stored in the order of first row and second column. In one category, if the i-th element of the array is 1, it means that the i-th pixel in the scanned image is stored in the second category in the order of first row and second column. The reverse is also possible, that is, the i-th element of the array is 1, which means that the i-th pixel in the scanned image is stored in th...

Embodiment 2

[0144] figure 2 It is a flow chart of the method for compressing color scanned images according to the present invention, such as figure 2 As shown, the method for compressing the color scanned image described in this embodiment includes:

[0145] (1) Read the r, g, b value of each pixel in the image, by the formula E=R 2 +G 2 +B 2 , to calculate the energy value of each point. Find the maximum value max_E and the minimum value min_E of the energy value in the image, and calculate their mean_E=(max_E+min_E) / 2.

[0146] (2) Use mean_E as the threshold, scan the original image in the order of row first and then column, and divide it into two categories, that is, two one-dimensional arrays A1 and A2, the data composition style of A1 and A2 is GBRGBRBR..., and obtain the value at the same time Flag1 is a one-dimensional flag array of 0 and 1, such as image 3 shown.

[0147] (3) Classify the classification results A1 and A2 with mean_E as the threshold in step (2) again acc...

Embodiment 3

[0157] Correspondingly, this embodiment provides a method to decompress the compressed file generated in Embodiment 2, and the overall schematic diagram of compression and decompression is as follows Figure 5 shown.

[0158] Figure 6 It is a flow chart of the method for decompressing color scanned images according to the present invention, as Figure 6 As shown, the scanned image decompression method described in this embodiment includes:

[0159] (1) Read in sequentially from the compressed image (according to the order of compression) the length, width, number of color bits of the original image, the length of each flag array, the length and data of the compressed flag array zip_flag, and the number of each type of array Original length, transformed length, DWT transformation series and low frequency component data of Y, U and V.

[0160] (2) The compressed flag array zip_flag is used as input for arithmetic coding decompression, and flag1, flag2, and flag3 are obtained...

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Abstract

The invention discloses a method for compressing and decompressing a single picture. The method includes creating at least one flag array, classifying pixels of a scanned picture into N types to be stored in the N array according to the preset mode, and recording storage positions of the pixels in the designation array; subjecting the pixels in the N array to direct-current level displacement; converting the scanned picture into YUV (luma and chroma) color space if the scanned picture is a colored picture of RGB (red, green and blue) mode; subjecting each array of the N array to one-dimensional wavelet transform according to each pixel component; and compressing the flag array, writing data into files according to preset sequence to obtain the compressed picture. Compression speed can be increased by classifying color or gray level of the picture by utilizing picture energy as criteria according to a mode of binary tree, picture information loss can be reduced to the greatest extent, high compression is realized and data quantity of the picture is greatly decreased.

Description

technical field [0001] The invention relates to the technical field of image compression, in particular to a compression and decompression method for a single image. Background technique [0002] The purpose of image compression coding is to represent the image with as few bits as possible, while maintaining the quality of the restored image as much as possible to meet the requirements of the intended application. Compressing the amount of data and improving effectiveness are the primary goals of image compression coding. [0003] There are two main reasons for image compression: [0004] One is image redundancy. Redundancies such as space, time, information entropy, structure and knowledge exist in images. Removing or reducing these redundancies can realize image compression. [0005] The second is human visual characteristics. Human vision is not sensitive to sharp changes in the edge (visual masking effect), and has weak color resolution. Using these features can pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N7/26H04N7/30H04N11/04H04N19/63
Inventor 张修宝高昊江
Owner 京北方信息技术股份有限公司
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