Pure Contourlet Transform Toolkit with Subband Coefficient Visualization

This text describes a modified "pure contourlet transform" toolkit that has been enhanced to display subband coefficients during both decomposition and reconstruction phases. The pure contourlet transform represents a directional multiresolution analysis technique widely applied in image processing and computer vision. The implementation typically involves a double filter bank structure: a Laplacian pyramid for multiscale decomposition followed by directional filter banks for capturing directional details. Key algorithmic improvements include coefficient visualization modules that track transform coefficients across decomposition levels, enabling real-time monitoring of subband energy distribution. This enhanced visualization capability allows researchers to better understand and analyze image details and features, particularly effective in capturing smooth contours and directional textures. The modified toolkit provides MATLAB functions like purecontourletdec() for decomposition and purecontourletrec() for reconstruction, with added plotting routines that graphically represent coefficient magnitudes at each directional subband. Through this technical enhancement, users can more effectively apply contourlet transforms for feature extraction, image compression, and texture analysis applications.