Process And Study On Restoration Of Ultrasonic Image

In recent years, with the arrival of information age, especially digital era, the application of ultrasonic imaging technology becomes more and more extensive. It plays a most important role in medical diagnosis and non-destructive testing in modern industry etc., with its advantage of safety, convenience, non-destruction, cheapness and so on.In the process of imaging, the lateral resolution of ultrasonic imaging system is lowered and the image is out of focus, because of beam spreading. What's more, another problem is that the spread of beam isn't consistent in whole field, which at the focal surface is better; otherwise which is farther from the focal surface, the beam spreads more seriously. As a result the development and application of ultrasonic imaging technology is limited largely. In order to observe/measure/diagnose effectively and advance the sensitivity and veracity of ultrasonic imaging, improving lateral resolution turns to be an imperative and practical task nowadays.Currently, we can only use physical way to solve the problem of low lateral resolution, for example multi-transducer instrument or dynamical focusing. Nevertheless the above ways all have certain limitation, such as circuital complications, costliness. Especially, the system with multi-transducers must augment the transducer, so it can't be applied in many cases, for instance, Ophthalmology examination.For solving above problem, this article adopts digital image post processing to process the ultrasonic image. The spread of beam is various, so different length of PSF is applied in different location of the whole image. Then image is processed respectively by iterative wiener filter to improve its lateral resolution and recover it wholly. In addition to evaluate the image intuitively by the medical knowledge, we put forward a criterion function of sum of squared difference with threshold; we also prove the availability of the criterion function by experiment. Finally we evaluate the image by the function to prove the availability of the restoration. Besides, it also proves the effectivity of improving the lateral resolution by digital image processing. Therefore we have found a new way to enhancing the quality of image.