Ultrasonic B-mode image enhancement based on level-dependent spread functions

The concept of level-dependent spatial summation is applied to the 2-dimensional amplitude distribution comprising an ultrasonic brightness image. The distribution is convolved with a level-dependent kernel. The size (i.e., extent) of the kernel is inversely proportional to the local signal level. The result is a 2-dimensional distribution of Mach bands, accentuating edges and providing useful information for the reduction of speckle. In addition, a small but powerful extension of the processing scheme is presented that supports global edge enhancement and contrast enhancement. The level of improvement has been quantified in terms of an increase in the lesion signal-to-noise ratio on the order of 60 percent. Only two system-dependent parameters have to be supplied for adjustment. The algorithm is rather insensitive to the exact choice of the parameters, making it quite robust. Since only a limited number of simple operations is required for the processing of a frame, the algorithm is expected to be suitable for real time application.