picture black(white)

In facsimile, that value of the chosen characteristic of the signal (e.g., its frequency or amplitude) which represents the darkest (or brightest) areas of the document being transmitted.; 在傳真通信中所選擇的信號特性值,表示所要傳送文卷的 最暗［最亮］部分的頻率或電平范圍。