Method for compressing and decompressing JPEG image without loss

Abstract

The invention relates to a lossless compression and decompression method for a JPEG image, wherein, the lossless compression method for the JPEG image is that: the invertible transform is carried outon JEPG image files in accordance with a wrapping rule, and the JPEG image files are transformed; and the transformed JPEG image files are compressed by LZ77 encoding or improved algorithm, and then the compression is finished. The compression approach on JPEG images is first to decompress the JPEG image files compressed by the LZ77 encoding or the improved algorithm, and then the JPEG image filesof invertible transform is obtained; and then the wrapping rule is applied to the JPEG image files of invertible transform for anti-wrapping, finally, the original JPEG image files are obtained. Thelossless compression and decompression method for the JPEG images can effectively remove 3-10 percentage of redundancy on the basis of the original compression ratio and at the same time cannot affectthe compression / decompression effect, featuring easy implementation.

Description

(1) Technical field: [0001] The invention relates to a data compression and decompression method, in particular to a JPEG image lossless compression and decompression method. (two) background technology: [0002] The pictures in JPEG format have the characteristics of high image quality, and are widely used in computer storage and computer network transmission of images, and most of the photos of existing ordinary digital cameras also use JPEG format. Because the image quality of the JPEG image is high, the space it occupies is relatively large. Taking an 8 million pixel digital camera as an example, the JPEG image produced by it can be as high as 5M bytes. In order to save storage space and reduce the time spent on image transmission, the original JPEG image file is usually compressed before being saved or transmitted. There are two types of existing compression methods, one is lossless compression, which regards data as a combination of information and redundancy, and its...

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Problems solved by technology

The other type is lossy compression, which not only removes or reduces the redundancy in the data, but also ignores some less important details, so it has a considerable compression ratio, but this compression method will lose some of the original file. Some information, resulting in a certain difference between the decompressed file and the original file

The existing compression methods, whether lossless or lossy, are to directly compress the original JPEG image file. Although this can achieve a certain compression ratio and reduce a certain amount of storage space and transmission time, the original JPEG image There is a certain degree of redundancy in the file due to the difference in the sequence it emits. This redundancy cannot be removed without regularizing the original JPEG image file. How to make a more effective regularization of the original JPEG image file Another way to increase the compression ratio

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