It is hard to reconcile this requirement with the manifestly indirect indoor illumination in the Arnolfini portrait and in many early Renaissance paintings adduced as evidence by Hockney.

• 这就与霍克尼引证的阿诺菲尼肖像及诸多文艺复兴早期绘画不一致了，他们的照明显然是室内的间接光线。