PROBLEM TO BE SOLVED: To achieve shielding processing suitable for an ultrasonic image.SOLUTION: An evaluation region 52 is a rectangular region (a cube) around coordinates P corresponding to the depth of a pixel of attention. A shielding ratio calculation part calculates a shielding ratio of the pixel of attention based on a plurality of differential values acquired from a plurality of visual lines 34 passing through the inside of the evaluation region 52 by acquiring a differential value between a depth to a shield portion and a depth to a border of the evaluation region 52 for each visual line 34 passing through the inside of the evaluation region 52. The shielding ratio calculation part calculates the differential value between the depth to the shield portion and the depth to the border of the evaluation region 52 for each visual line 34 passing through the inside of the evaluation region 52 using depth data stored in a depth data storage part.SELECTED DRAWING: Figure 3COPYRIGHT: (C)2019,JPO&INPIT【課題】超音波画像に好適な遮蔽処理を実現する。【解決手段】評価領域52は、注目画素の深さに対応した座標Pを中心とする矩形領域(立方体)である。遮蔽率算出部は、評価領域52内を通る各視線34ごとに遮蔽部位までの深さと評価領域52の境界までの深さの差分値を得ることにより、評価領域52内を通る複数の視線34から得られる複数の差分値に基づいて注目画素の遮蔽率を算出する。遮蔽率算出部は、深度データ記憶部に記憶された深度データを利用して評価領域52内を通る各視線34ごとに遮蔽部位までの深さと評価領域52の境界までの深さの差分値を算出する。【選択図】図3
