Image Enhancement of X-ray Bone Images Using Modified Local Histogram Equalization

Nowadays X-ray imaging is a commonly used procedure in medical diagnosis. For doctors it is very important to be able to find as much details as possible from the image. Until images were acquired in a digital form it was impossible to alter their appearance. Recently more and more X-ray systems output digital images which can be enhanced using various image processing techniques. One of them is histogram equalization which is known for quite some time. In certain cases its derivation, the so called local histogram equalization, can result in an even better performance. In this paper a research of local histogram equalization is presented for the case of an X-ray image of a bone fracture with a fixture. This image is characterized with wide histogram with very small local variations. Common local histogram equalization technique was further modified in order to enable to see the bone structure even in the areas obscured by the fixture and screws.