Hockney and falco explain this shift as follows : van eyck traced part of the image projected in an epidiascope , then accidentally bumped the silverpoint , the oil or the mirror , and finally traced the remaining , now shifted , image 霍克尼与法柯对此位移的解释如下：范艾克用幻灯机描了部份的影像后，不小心碰到银尖笔、油画、或者镜子，然后继续描完剩下已经位移的影像。
