University of São Paulo, School of Engineering, Biomedical Engineering Laboratory, São Paulo, Brazil.
University of São Paulo, School of Dentistry, Department of Surgery, Maxillofacial Prosthesis, and T, Brazil.
J Biomed Opt. 2021 Feb;26(2). doi: 10.1117/1.JBO.26.2.025002.
Rehabilitation through facial prostheses' main goal is to aid individual's social reintegration as well as improving their quality of life. However, this treatment is not yet widely available in Brazil due to the lack of specialized clinics and the cost associated with the high number of necessary medical appointments until the final result. One of the steps in the process consists of measuring skin color, which is observer-dependent and may suffer from the effect of metamerism.
The methodology of our work aims to obtain a standard between different devices and greater fidelity to the color seen in person in order to reduce face-to-face iterations, reduce costs, and ensure better final results.
A physical device and a computer program were improved from previous projects. The changes included implementing the Thin-Plate Spline 3D algorithm for color calibration, in addition to an optional non-uniform illumination correction in the process. We also aim to improve the project's accessibility using a colorimeter. The methodology and the algorithms were both compared to readings from direct skin measurements as well as color references.
After processing, the ΔEab* metric between images from the same segments is taken with different cameras and conditions of illumination decreased from 18.81 ± 4.85 to 4.85 ± 1.72. In addition, when the images were compared to colorimetric readings of the skin, the difference went from 14.93 ± 4.11 to 5.85 ± 1.61. It was also observed that using a less expensive device did not impact the readings. The project is open source and available at Github.
The results demonstrate the possibility of applying the methodology to assist in the manufacturing of facial prostheses to decrease the total number of consultations, in addition to providing greater reliability of the final result.
通过面部假体进行康复的主要目标是帮助个人重新融入社会并提高他们的生活质量。然而，由于缺乏专门的诊所以及与完成最终结果所需的大量医疗预约相关的成本，这种治疗在巴西尚未广泛普及。该过程中的一个步骤包括测量肤色，而肤色是依赖观察者的，并且可能会受到同色异谱的影响。
我们工作的方法旨在获得不同设备之间的标准，并更忠实地反映人眼所见的颜色，以减少面对面的迭代次数、降低成本并确保更好的最终结果。
改进了之前项目中的物理设备和计算机程序。更改包括实施用于颜色校准的薄板样条 3D 算法，以及在该过程中可选的非均匀照明校正。我们还旨在通过比色计提高项目的可访问性。该方法和算法都与直接皮肤测量读数以及颜色参考进行了比较。
处理后，相同片段的不同相机和照明条件下的图像之间的ΔEab*度量值从 18.81 ± 4.85 减少到 4.85 ± 1.72。此外，当将图像与皮肤的比色读数进行比较时，差异从 14.93 ± 4.11 减少到 5.85 ± 1.61。还观察到使用较便宜的设备不会影响读数。该项目是开源的，并可在 Github 上获得。
结果表明，可以应用该方法来辅助面部假体的制造，以减少总咨询次数，并提高最终结果的可靠性。
