Multilevel IPVO based reversible watermark calculating method

Abstract

The invention provides a multilevel IPVO based reversible watermark calculating method. A watermark algorithm is completed via a watermark embedding step and a watermark extracting and original image recovery step. In the watermark embedding process, image blocks are laid and positioned, whether an image block is positioned in a smooth area or a texture area is determined via calculation, and the image blocks in different areas are processed in different manners. Preferably, the image block in the smooth area is divided into two portions, the median of the image block is kept unchanged, and predicted calculation is realized by taking the median as a basic point. The smooth blocks are processed in different manners, the embedded data capacity of a watermark is improved, and watermark extraction and original image recovery are carried out to solve the problem of image distortion effectively.

Description

technical field [0001] The invention relates to the field of multimedia signal processing, and more specifically, to a multi-layer IPVO-based reversible watermark calculation method. Background technique [0002] In the existing technology, the traditional digital watermarking technology will cause permanent distortion of the host image, but some practical applications do not allow a little permanent modification of the host image, such as medical, military and judicial fields. Taking medical images as an example, the acquisition of each medical image requires the completion of precision instruments and the support of costs. The large image distortion may cause misdiagnosis. For example, for an ECG (electrocardiographic) signal map, the signal curve at any point Abnormalities may be interpreted as some kind of pathological features. It can be seen that the traditional digital watermarking technology is not suitable for medical images. Therefore, the technology of reversibl...

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Problems solved by technology

[0035] From the above reversible watermark calculation method, it can be seen that in the prior art, all smooth blocks have the same smoothness, so the same processing method is used for each smooth block, but in fact, the smoothness of smooth blocks is also limited. There is a big difference, blocks with high smoothness level should carry more watermark bits than blocks with low smoothness level

This method of treating all smooth blocks equally does not improve the data capacity of watermark embedding. Under certain circumstances, it will also cause the problem of inaccurate signal processing, resulting in image distortion.

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