複数の空間周波数を含む画像に対する焦点調節特性と焦点調節手がかり

摘要

This report discusses what cues drive the accommodation mechanism in human vision. The stimuli used in the experiments were still square and sine waves and compound waves composed of the drifting square wave with the spatial frequency of 3 cpd and one of square, sine, and missing fundamental (MF) waves with different spatial frequencies. The accommodative responses were measured using an infrared optometer during paying attention to each image. The following results were obtained: (1) although the accommodation errors for still square waves were the same as those for sine waves in decreasing with an increase in the spatial frequency, they were different in changing with the viewing point; (2) although those for drifting square waves were the same as those for drifting sine waves in decreasing with an increase in the spatial frequency, they were different in decreasing with the drifting speed. These results suggest that spatial features (edges or regions between edges) as well as spatial frequency can be accommodative cues to drive the accommodation mechanism in human vision.%従来，単一空間周波数の静止正弦波や複合ドリフト正弦波に対する焦点調節特性が実測されてきた．本報告では，複数の空間周波数を含む静止画像や複合ドリフト画像に対する焦点調節応答を赤外線オプトメータを用いて実測し，従来結果との共通点，相違点を明らかにすることにより，焦点調節機構の駆動情報（手掛かり）にっいて検討する．その結果，（1）静止方形波画像では，空間周波数に依存した焦点調節応答値の変化は正弦波と同様であるが，視点位置に依っても焦点調節応答値が変化すること，（2）方形波と方形波又は基本波無し方形波の複合ドリフト画像に対する焦点調節応答値は正弦波を用いた場合と同様であるが，ドリフト速度の低下に伴い位相（エッジやエッジ間中心）の影響による焦点調節応答値の増加傾向が示された．上記結果は，空間周波数以外にも空間的特徴（エッジや基本周期構造）が調節の手掛りになり得ることを示唆する．