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Research on information hiding technology based on color still digital images (I)

information hiding technology of digital images is one of the most challenging and active research topics in the field of digital image processing. This paper summarizes the information hiding technology of digital images, and presents a new information hiding algorithm based on color still digital images

1 introduction

with the rapid development of the information industry represented by microelectronics technology, multimedia, computer network, personal mobile communication technology and so on have entered the homes of ordinary people. Digitalization has been deeply rooted in the hearts of the people, and the networking wave spearheaded by the Internet has swept the world. According to statistics, visual information is the most important information that people collect through sensory organs in daily life. Then, in digital life, digital image has become the most important form of information that people perceive [1]

digital images can be divided into still images and dynamic images, which are generally called video images. Each frame of video image can be regarded as a still image, but these still images are not isolated from each other, but there is correlation on the time axis. A still image is a collection of pixels, and the actual distance corresponding to adjacent pixels is called the spatial resolution of the image in short. According to the different color information of pixels, digital images can be divided into binary images, gray images and color images. The final receiver of digital images is the human eye. The pixel values of two digital images with very same quality that the human eye senses may be very different. In this way, relying on the imperfection of human visual system (HVS), it provides a very large space for distortion compression and information hiding of digital images

information hiding is different from information encryption. Information encryption is the content of hidden information, and information hiding is the existence of hidden information. Information hiding is more secure than information encryption, because it is not easy to attract the attention of attackers

2 overview of information hiding technology

2.1 introduction to information hiding

information hiding, also known as data hiding, or digital watermarking. In short, information hiding refers to the process of embedding one signal (generally known as signature signal) into another signal (generally known as host signal, or cover media). After embedding the information, the cover media becomes a stegano media. This embedding process needs to meet the following conditions [3]:

imperceptibility of the signature signal. In other words, after the signature signal is embedded, the perceptual characteristics of the main signal have not changed significantly, and the signature signal is "hidden" by the main signal

robustness of signature signal. The signature signal should be robust to various distorted transformations of the main signal, such as distorted signal compression, affine transformation, noise addition, a/d or d/a conversion, as well as various malicious attacks. Unless the perceptual characteristics of the main signal are obviously destroyed, the signature signal will be difficult to be removed

generally speaking, the embedding of signature signals does not increase the storage space and transmission bandwidth of the main signal. In other words, after the signature signal is embedded, it is difficult to detect the change of information on the "surface"

the development history of information hiding can be traced back to the use of "steganography". The word "invisibility" comes from the combination of "hidden" and "figure" in ancient Greek. Although "invisibility" and "cryptography" are both technologies dedicated to the confidentiality of information, their design ideas are completely different. "Cryptography" can't make the confidential information unreadable without upgrading and substituting the latest plastic technology mainly through design encryption. However, for non authorized persons, although they can't get the specific content of the confidential information, they can be aware of the existence of the confidential information. While "invisibility" is dedicated to making unauthorized persons have no way to know whether confidential information exists or not through well-designed methods. Compared with modern cryptography, which must be plugged into a power socket with protective grounding, the biggest advantage of information hiding is that it does not restrict the access and access to the main signal, but is committed to the security and confidentiality of the signature signal

2.2 basic framework of information hiding algorithm

the following part gives the basic framework of information hiding algorithm based on orthogonal transformation, including embedding process and detection process, as shown in Figure 2.1 and Figure 2.2 respectively

algorithm 2.1 (information hiding and embedding algorithm based on change domain)

orthogonal transform the original main signal

perceptual analysis of the original main signal

on the basis of step (2), the signature signal is embedded into the main signal in the transform domain based on the given keyword, and the main signal with hidden information is obtained

figure 2.1 embedding process of information hiding algorithm