RESUMEN
An inexpensive image processing system, assembled from commercially available components and driven by "in-house" software, was tested as a means of processing radiographs obtained in a radiology department. In this preliminary study, the main interest was to investigate, through subjective appraisal, the ability of the system to recover the image quality of poorly exposed radiographs. Subsidiary objectives were to obtain some information regarding the specification limits of the system and its components, as well as some quantitative estimate of its advantages for clinical diagnosis. The system was used to process a set of film radiographs of an anthropomorphic chest phantom, produced under conditions that were designed to provide a wide range of image qualities. Following this, four sets of randomly ordered processed and unprocessed images were formally assessed by a group of experienced observers. Consensus opinion from the group indicated that significant improvement could be obtained through simple image processing. Some radiographs regarded as unacceptable became, after processing, acceptable to viewers.
Asunto(s)
Interpretación de Imagen Asistida por Computador , Microcomputadores , Interpretación de Imagen Radiográfica Asistida por Computador , Humanos , Intensificación de Imagen RadiográficaRESUMEN
The physical quality of a digitised image is affected by non-digital processes in the imaging instrumentation and by digital processes in the computer. The spatial unsharpness depends on instrumental resolution and on the pixel size of the digital array. The image contrast depends on the properties of the imaging system and on the number of grey scales used in the digital sampling process. The possibility is examined of constructing formulae for spatial unsharpness, and for the analogous parameter in the intensity dimension, defined as threshold contrast, in terms of instrumental and digital components. Formulae are developed from simple principles and tested against the observed properties of computer simulated images. The conclusion is that the concepts and the formulae provide a basis for predicting the effects of digital processing on the total unsharpness and contrast of digitised images.