| 摘要 |
A method for converting a digital image to an analog-simulative film-like digital image is described wherein input pixel values (designated X) from the original digital image are converted to film-like output values (designated Y) wherein Y=AXp+B. The input values X, which range from Xmin to Xmax, are divided into consecutive intervals wherein different values of A, p, and B are applied for each interval. Most preferably, three intervals are defined so as to correspond to low, medium, and high light/radiation response intervals on film. In a low light/radiation region wherein X<X1, A is generally chosen to be less than 1 to provide range compression at the low end of the input dynamic range, and p is generally chosen to be greater than 1 to provide increasing light response. In a high light/radiation region wherein X>X2, p is generally chosen to be less than 1 to provide range compression. In the intermediate medium light/radiation region, p is preferably chosen to be approximately 1 to provide a response which is linear with respect to the input, but A is preferably chosen to be greater than 1 to provide range expansion. An image formed in accordance with the resulting output values Y provides an exceedingly good representation of a filmed radiographic image, and may be printed on translucent film for use and analysis in the same manner as a filmed radiographic image produced by analog methods. Additionally, the output values Y can be made to even more accurately mimic the response of film if the aforementioned conversion is expanded in accordance withwherein M is an integer value greater than 1.
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