| 摘要 |
PROBLEM TO BE SOLVED: To precisely separate a specific image part from radiation noise and emphasize it even for a source image having much radiation noise by correcting a conversion table between an edge signal and an emphasis coefficient and/or a conversion table between a specific image signal and the emphasis coefficient according to the dosage of irradiating radiation. SOLUTION: In a conversion table 16, the emphasis coefficient βcorresponds to 0 within a range wherein the edge signal is from 0 to a threshold value A. In a range wherein the signal is from the threshold value A to a threshold value B, the edge signal and emphasis coefficient β increase linearly and monotonously and in a range above the threshold value B, the emphasis coefficient βis fixed to 1. The threshold values A and B are both determined as to a reference image having optimum dosage of irradiating radiation. The threshold value A is an optimum value for emphasizing the edge part of the image and the threshold value B, on the other hand, is set as an optimum value for suppressing overemphasis since a high frequency component is also large within a range wherein the edge signal is large to some extent. |
