A novel contrast equalization method for chest radiograph

This paper proposed a novel contrast equalization algorithm for display or print ready processing of x-ray chest radiograph based on a multi-scale decomposition and reconstruction architecture. Firstly, using this architecture, the original image is decomposed into multi-scale components. At this stage, three methods are used. The first two methods are based on Gauss convolution filters and the third is based on mean curvature motion equation, which is one of nonlinear partial differential equation (PDE) models. Secondly the components at different scale are weighted using a set of controlled equalization coefficients and then integrated into the display or print ready image to ensure the improvement of the visibility of weakly contrasting details and the contrast between tissues in different area. Preliminary experiments on clinical images in deed testify the superiority of our algorithm. This algorithm can effectively improve contrast of low-contrast-region, increase the detail visibility of the rendered image to CRT or film as the image latitude has adequate broad.