Objective color calibration for manufacturing facial prostheses

SIGNIFICANCE

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.

AIM

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.

APPROACH

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.

RESULTS

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.

CONCLUSIONS

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.

Forensic sexual assault examination and genital injury: is skin color a source of health disparity?

PURPOSE

The study objectives were to (1) estimate the frequency, prevalence, type, and location of anogenital injury in black and white women after consensual sex and (2) investigate the role of skin color in the detection of injury during the forensic sexual assault examination.

METHODS

A cross-sectional descriptive design was used with 120 healthy volunteers who underwent a well-controlled forensic examination after consensual sexual intercourse.

RESULTS

Fifty-five percent of the sample had at least 1 anogenital injury after consensual intercourse; percentages significantly differed between white (68%) and black (43%) participants (P = .02). Race/ethnicity was a significant predictor of injury prevalence and frequency in the external genitalia but not in the internal genitalia or anus. However, skin color variables--lightness/darkness-, redness/greenness-, and yellowness/blueness-confounded the original relationship between race/ethnicity and injury occurrence and frequency in the external genitalia, and 1 skin color variable--redness/greenness--was significantly associated with injury occurrence and frequency in the internal genitalia.

CONCLUSIONS

Although differences exist in anogenital injury frequency and prevalence between black and white women, such differences can be more fully explained by variations in skin color rather than race/ethnicity. Clinical recommendations and criminal justice implications are discussed.