Abstract: A process for enhancing a still video image can correct digital fluoroscopy images which are under- or overexposed and have their image brightness values concentrated to one end of the gray scale. A pixel histogram is formed, but is clipped at a low value. Then, a cumulative histogram is formed from the clipped histogram. The cumulative histogram, which has a generally linear slope, is normalized and is used for mapping the brightness of luminance values of the original image. The new values form an optimal video image with the gray scale values spread over the entire range. The image shows details not only in the middle gray areas, but in the light and dark areas as well.

Abstract: Method and apparatus for determining the refractive index of an optical film over a wide spectral range is described that involves measuring the changing radiant reflectance (or transmittance) of the film at various wavelengths as it is being deposited upon a substrate, as for example by vacuum deposition process. By determining the values of the extreme limits, an envelope of the peak reflectance can be developed from which the film's index of refraction is obtained over the entire spectral range that is situated between the two extreme wavelength channels.