Reflectance Transformation Imaging (RTI) (Malzbender et al., 2001) is a photometric stereo technique that enables the interactive relighting of the object of interest from novel lighting directions, and an estimation of surface topography through the calculation of surface normal vectors. We propose a novel, fully automated technique for correcting common lighting errors in RTI and markedly improve the accuracy of surface normal estimation, as well as increasing the legibility of low relief surface variations. This moves RTI from the qualitative domain (e.g. enabling the reading of weathered inscriptions) into the quantitative domain of computer vision. RTI assumes only light direction, and not received intensity, changes as the object is imaged. Like other authors we show that this assumption is false and propose a novel method to correct for it. However, we estimate the lighting directions automatically, unlike other proposed correction techniques. Our method also requires no calibration equipment, meaning it can be easily retrofitted to any existing stack of RTI photographs. We increase the simplicity of the standard highlight RTI method by automatically detecting lighting directions and maintain its appeal to non-imaging professionals.

反射率转换成像（RTI）（Malzbender等人，2001）是一种光度立体技术，能够从新颖的照明方向对感兴趣的对象进行交互式重新照明，并通过计算表面法向矢量来估计表面形貌。我们提出了一种新颖的全自动技术，用于纠正RTI中常见的照明错误，并显着提高表面法线估计的准确性，并增加低起伏表面变化的可读性。这将RTI从定性领域（例如，能够读取风化的铭文）转移到计算机视觉的定量领域。RTI假定仅光线方向发生变化，而没有接收到强度随对象成像而变化。像其他作者一样，我们证明了这一假设是错误的，并提出了一种新颖的方法对其进行纠正。但是，与其他建议的校正技术不同，我们会自动估算照明方向。我们的方法也不需要校准设备，这意味着可以轻松地将其改装为任何现有的RTI照片堆栈。我们通过自动检测照明方向来增加标准高光RTI方法的简便性，并保持其对非成像专业人员的吸引力。