Fluctuating asymmetry of dynamic smiles in normal individuals.

The aim of this study was to quantify the fluctuating dynamic facial asymmetry during smiling in a group of 'normal' adults, using three-dimensional (3D) motion facial capture technology. Fifty-four male and 54 female volunteers were recruited. Each subject was imaged using a passive markerless 3D motion capture system (DI4D). Eighteen landmarks were tracked through the 3D capture sequence. A facial asymmetry score was calculated based on either a clinically derived midline or Procrustes alignment; scores were based on the Euclidean distance between landmark pairs. Facial asymmetry scores were determined at three time points: rest, median, and maximum frame. Based on the clinically derived midline and on Procrustes alignment, the differences between male and female volunteers, as well as those at the three different time points, were not clinically significant. However, throughout a smile, facial and lip asymmetry scores increased over the duration of the smile. Fluctuating facial asymmetry exists within individuals, as well as between individuals. Procrustes superimposition and the clinically derived midline produced similar asymmetry scores and both are valid for symmetrical faces. However, with facial asymmetry, Procrustes superimposition may not be a valid measure, and the use of the clinically derived midline may be more appropriate, although this requires further investigation.

Quantitative dynamic analysis of the nasolabial complex using 3D motion capture: A normative data set.

INTRODUCTION: Smile reanimation should be considered from a dynamic perspective. Any intervention should restore normality. To date no such normative dynamic data has been published. AIM: To quantitatively analyse maximal smiles between a healthy group of Caucasian male and female adults using 3D motion capture (4D stereophotogrammetry). METHOD: Using a 3D facial motion capture system 54 males and 54 female volunteers were imaged whilst performing a maximal smile. Eight nasolabial landmarks were digitised and tracked. Differences in displacement and speed of bilateral landmarks between males and females were analysed in each direction (x, y, z and Euclidian), from rest (T0), to median smile (T1) and maximal smile (T2), using paired t-tests and Wilcoxon-Signed Rank tests. RESULTS: In males and females the displacement and speed of the left and right alar base landmarks were similar in the x and y directions but less in the z direction. For the philtrum, the displacement and speed of the bilateral landmarks were similar in the y and z directions, but less in the x direction. The left alar base and left philtrum moved significantly more in males. Left and right cheilion moved a similar amount in the x and y directions but more in the z direction. Labiale superius moved significantly more in the z direction, and labiale inferius moved significantly more in the y direction in males. In conclusion, this study has presented a novel normative data set of dynamic nasolabial complex movement for males and females during maximum smile. The data, as well as providing magnitudes of displacements of the nasolabial complex, also provides the speeds of movement.

The difference between registered natural head position and estimated natural head position in three dimensions.

This study determined the intra-rater and inter-rater reliability of re-orientating three-dimensional (3D) facial images into the estimated natural head position. Three-dimensional facial images of 15 pre-surgical class III orthognathic patients were obtained and automatically re-orientated into natural head position (RNHP) using a 3D stereophotogrammetry system and in-house software. Six clinicians were asked to estimate the NHP of these patients (ENHP); they re-estimated five randomly selected 3D images after a 2-week interval. The differences in yaw, roll, pitch, and chin position between RNHP and ENHP were measured. For intra-rater reliability, the intra-class correlation coefficient (ICC) values ranged from 0.55 to 0.77, representing moderate reliability for roll, yaw, pitch, and chin position, while for inter-rater reliability, the ICC values ranged from 0.38 to 0.58, indicating poor to moderate reliability. The median difference between ENHP and RNHP was small for roll and yaw, but larger for pitch. There was a tendency for the clinicians to estimate NHP with the chin tipped more posteriorly (6.3±5.2mm) compared to RNHP, reducing the severity of the skeletal deformity in the anterior-posterior direction.

A deblocking technique for block-transform compressed image using wavelet transform modulus maxima.

In this work, we introduce a deblocking algorithm for Joint Photographic Experts Group (JPEG) decoded images using the wavelet transform modulus maxima (WTMM) representation. Under the WTMM representation, we can characterize the blocking effect of a JPEG decoded image as: 1) small modulus maxima at block boundaries oversmooth regions; 2) noise or irregular structures near strong edges; and 3) corrupted edges across block boundaries. The WTMM representation not only provides characterization of the blocking effect, but also enables simple and local operations to reduce the adverse effect due to this problem. The proposed algorithm first performs a segmentation on a JPEG decoded image to identify the texture regions by noting that their WTMM have small variation in regularity. We do not process the modulus maxima of these regions, to avoid the image texture being "oversmoothed"by the algorithm. Then, the singularities in the remaining regions of the blocky image and the small modulus maxima at block boundaries are removed. We link up the corrupted edges, and regularize the phase of modulus maxima as well as the magnitude of strong edges. Finally,the image is reconstructed using the projection onto convex set (POCS)technique on the processed WTMM of that JPEG decoded image.This simple algorithm improves the quality of a JPEG decoded image inthe senses of signal-to-noise ratio (SNR) as well as visual quality. We also compare the performance of our algorithm to the previous approaches,such as CLS and POCS methods. The most remarkable advantage of the WTMM deblocking algorithm is that we can directly process the edges and texture of an image using its WTMM representation.