Contrast adjustment of radiological images using liquid crystal devices

When trying to view a radiological image (x-ray) with a full range of optical densities, it can be impossible to see detail in very dark parts of the image if there are also very bright parts. A technique which uses a liquid crystal device to improve the visibility of such images by selective reduction of the optical density range in parts of the image is described. A nematic liquid crystal device (such as that typically used in an overhead projector display) is employed within an apparatus that incorporates feedback to selectively mask bright parts of a radiological image. Obvious visual improvements were obtained using the technique, presenting the potential of a device system for improved analysis of certain radiological images.