Applications of adaptive feedback line enhancer in signal and image enhancement

In this paper, two new approaches are proposed for the design of adaptive feedback line enhancer to be used in signal and image enhancement. In the first approach, the performance of an adaptive cross-coupled line enhancer is improved by maximizing the cross correlation functions between the outputs of the cross-coupled line enhancer, over a specified lag length. Next the performance of the line enhancer has been improved and made free from any stability constraint that normally arises in the cross coupled case, by realizing one of the cross-coupled structures, as a lattice filter with feedback. The lattice parameters are recursively updated as new data comes in using the simple LMS algorithm. Illustrative examples are given to show the effectiveness of the proposed approaches, even in case of colored noise with high eigenvalue spread. In case of image enhancement, the proposed cross-coupled structure is implemented in a 2D form. Stability of the resulting 2D feedback structure is easily checked and maintained. The simplicity of the proposed algorithms, allows the inclusion of any edge preserving routines if desired. Simulation results have again demonstrated the effectiveness of the proposed approaches, in both mage enhancement as well as edge preserving.