Image lossless compression method based on controllable-parameter encryption and compression algorithm

Abstract

The invention proposes an image lossless compression method based on a controllable-parameter encryption and compression algorithm. The method is a lossless compression method for images. An image is decomposed into high- and low-frequency image sub-bands through one-dimensional wavelet transform. Then, the edge of each sub-band is adaptively predicted to get an analog image with better continuity. The first line of the analog image is coded through a JPEG-Ls algorithm. Through compression ratio control, the compression ratio of a current image block is collected in the compression process of a previous image block. The distortion parameters are finely adjusted based on the compression ratio, so that the next image sub-block can be adjusted. Thus, compression converges to a given compression ratio, and a process of compression control based on the compression ratio is realized. A random sequence is generated for the code stream, the random sequence is processed to generate a random key stream, and the image sub-block compression code stream is encrypted using the key stream. The process repeats. Thus, the whole image can be encrypted and compressed.

Description

[0001] Field [0002] The invention relates to the field of computer information technology, in particular to the field of image compression. Background technique [0003] Image compression is divided into lossless compression and lossy compression, each with different application fields, because lossless compression can better preserve the original image information, lossless compression or near-lossless compression is more meaningful than lossy compression in some occasions, At the same time, in order to improve the security of the image during transmission, the image needs to be encrypted. At the same time, encryption processing can also avoid data loss or change caused by image transmission. Therefore, the combination of image lossless compression or near-lossless compression and encryption technology has gradually become a new research direction. [0004] Today's lossless image compression has great disadvantages. First, it cannot obtain a high compression ratio, which c...

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Problems solved by technology

[0004] Today's lossless image compression has great disadvantages. First, it cannot obtain a high compression ratio, which causes pressure on high-precision image transmission. Second, image information is easily lost or changed during image transmission and exchange. The image error is large, and the original intention of lossless compression is lost. Therefore, maintaining good image reconstruction quality and security during transmission and achieving a high image compression ratio are the current research directions

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