INPUT GREY VALUES COMPARED WITH CONTRAST PROFILES - A CONTRIBUTION TOTHE DISCUSSION ON OPTIMIZATION OF EVALUATION PARAMETERS IN STORAGE PHOSPHORUS RADIOGRAPHY

On comparing the individual imaging stages in conventional and digital image radiography it becomes evident that a significant advantage of the digital method is the possibility to adapt the image character and exposure dose individually to various problems requiring an answer. T o take advantage of this it is imperative to optimise image processing with care, especially contrast processing. No systematic procedure ba sed on objective criteria had existed to date. This paper describes a method of taking into account both the diagnostic significance of the structures to be imaged and their distribution within the relevant den sity range, in order to arrive at the best possible contrast conversio n. A prerequisite is to know for every kind of imaging which distribut ion of grey values pertaining to the relevant structures can be expect ed before digital image processing (initial grey values). This distrib ution determines the most favourable contrast conversion. The processi ng parameters for several types of imaging were optimised by this meth od. The method is demonstrated via thoracic images of newborn and chil dren.