Path generation is an optimization problem mainly performed on grid square maps that combines generation of paths with minimization of their cost. Several methods that belong to the class of exhaustive searches are available; however, these methods are only able to obtain a single path as a solution for each iteration of the search. Hence, this paper proposes a new method using genetic algorithms for this problem with the goal of simultaneously searching for multiple candidate paths.

This paper proposes a novel CT image coding concept named LOI which stands for level of interest and coding methods based on that concept. The well-known ROI (region of interest) coding gives priority to pixels in particular regions of an image when encoding or decoding the image. Similarly, LOI coding gives priority to the pixels having a particular pixel level. LOI is ideal for coding of CT images and offers remarkably high coding efficiency. This paper proposes two types of LOI coding methods. One type is the floating point method and the other is the integer method. This paper verifies that the both types improve coding efficiency of pixels in the LOI window. This paper also shows that adequate image quality is obtained even if the viewing window is different from the LOI window.

The residual correlation of the Hadamard transforms of stationary Markov-1 signals is investigated. It is shown that the decorrelation in the Hadamard domain is not substantially improved by increasing the block size or the number of data points. This is in sharp contrast with the DFT and other sinusoidal transforms known for their asymptotic equivalence to the KLT. The computational simplicity of the Hadamard transform is counterbalanced by its poor decorrelating capability. Comparison of the Hadamard and Fourier transforms in their decorrelating performance is included.

A few important properties of the fast Karhunen-Loeve transform (FKLT) proposed by Jain [3] are discussed. The purpose here is to emphasize the role of the boundary conditions upon which the entire theory is based. The effects of the zero boundary conditions are also discussed. It is argued that the transform is not as efficient as it might appear when used in bit rate reduction.