Fast Fractal Image Encoding Based on Special Image Features

The fractal image encoding method has received much attention for its many advantages over other methods, such as high decoding quality at high compression ratios. However, because every range block must be compared to all domain blocks in the codebook to find the best-matched one during the coding procedure, baseline fractal coding （BFC） is quite time consuming. To speed up fractal coding, a new fast fractal encoding algorithm is proposed. This algorithm aims at reducing the size of the search window during the domain-range matching process to minimize the computational cost. A new theorem presented in this paper shows that a special feature of the image can be used to do this work. Based on this theorem, the most inappropriate domain blocks, whose features are not similar to that of the given range block, are excluded before matching. Thus, the best-matched block can be captured much more quickly than in the BFC approach. The experimental results show that the runtime of the proposed method is reduced greatly com- pared to the BFC method. At the same time, the new algorithm also achieves high reconstructed image quality. In addition, the method can be incorporated with other fast algorithms to achieve better performance Therefore, the proposed algorithm has a much better application potential than BFC.

Fast Fractal Image Encoding Using an Improved Search Scheme

As fractal image encoding algorithms can yield high-resolution reconstructed images at very high compression ratio, and therefore, have a great potential for improving the efficiency of image storage and image transmission. However, the baseline fractal encoding algorithm requires a great deal of time to complete the best matching search between the range and domain blocks, which greatly limits practical applications of the algorithm. In order to solve this problem, a necessary condition of the best matching search based on an image feature is proposed in this paper. The proposed method can reduce the search space significantly and excludes the most inappropriate domain blocks for each range block before carrying out the best matching search. Experimental results show that the proposed algorithm can produce good quality reconstructed images and requires much less time than the baseline encoding algorithm. Specifically, the new algorithm can speed up encoding by about 85 times with a loss of just 3 dB in the peak signal to noise ratio （PSNR）, and yields compression ratios close to 34.

Projectile-Borne Video Reconnaissance System

Aiming at applications as a projectile-borne video reconnaissance system, the overall design and prototype in principle of a mortar video reconnaissance system bomb were developed. Mortar launched test results show that the initial integrated system was capable of transmitting images through tens of kilometers with the image resolution identifying effectively tactical targets such as roads, hills, caverns, trees and rivers. The projectile-borne video reconnaissance system is able to meet the needs of tactical target identification and battle damage assessment for tactical operations. The study will provide significant technological support for further independent development.

Colored object encoding scheme in ghost imaging system using orbital angular momentum

A colored object encoding scheme in a ghost imaging （GI） system using orbital angular momentum is in- vestigated. A colored object is decomposed into three components and then each component is obtained in the idler arm using a multiple grayscale encoding scheme. Afterward, we synthesize the three reconstructed components into a colored image. The scheme is conducted and then presented through numerical simula- tions and experiments. The simulation result shows that the average peak signal-to-noise ratio （PSNR） is at 21.636 for the reconstructed color of the ＂Lena＂ image with 255 gray scales. The experiment also shows that the PSNR is 8.082 for the reconstructed color of the ＂NUPT＂ characters. The successful imaging of colored obiects extends the further use of the GI technique

Security enhancement for double-random phase encryption using orthogonally encoded image and electronically synthesized key data

We prot）ose a security-enhanced double-random phase encryption （DRPE） scheme using orthogonally encoded image and electronically synthesized key data to cope with the security problem of DRPE technique caused by fixed double-random phase masks for eneryption. In the proposed scheme, we adopt the electronically synthesized key to frequently update the phase mask using a spatial light modulator, and also employ the orthogonal encoding technique to encode the image and electronically synthesized key data, which can enhance the security of both data. We provide detailed procedures for eneryption and decryption of the proposed scheme, and provide the simulation results to show the eneryption effects of the proposed scheme.