Method of and apparatus for processing radiation image

A radiation image processing apparatus comprising

• a subtraction processing means which detects a plurality of original image signals which represent a plurality of radiation images obtained by exposing recording media to radiations with different energy levels which have passed through an object constituted of a plurality of tissues exhibiting different levels of radiation absorptivity with respect to radiations with different energy levels, and obtains an extracted image signal representing an extracted image of a predetermined tissue in the object on the basis of said plurality of original image signals, and
• a frequency response processing means which obtains a processed image signal representing a processed image by calculating a processed image signal component S' corresponding to a predetermined picture element in the extracted image according to formula
• S'=Sorg+.beta..multidot.(S-Sus)
• wherein Sus represents an unsharp mask signal obtained by averaging the extracted image signal components corresponding to a number of picture elements which surrounds a predetermined picture element within a predetermined region, Sorg represents the original image signal component corresponding to said predetermined picture element, S represents the extracted image signal corresponding to said predetermined picture element, and .beta. represents a coefficient, and by repeating the calculation according to said formula with all the picture elements in the extracted image being sequentially taken as said predetermined picture element, thereby obtaining processed image signal components for all the picture elements in the processed image.