Fingerspelling recognition in the wild with iterative visual attention
Table 5: Impact of size noise on letter accuracy for face ROI and face scale setups. IoU is measured between the perturbed and original bounding boxes.
['[ITALIC] σs', 'IoU', 'Face ROI', 'Face Scale']
A face detector is used in two experimental setups: face ROI and face scale. To see how robust the model is to face detection errors, we add noise to the bounding box output by the face detector. Specifically, two types of noise were separately added: size noise and position noise. For size noise, we perturb the actual face detection boxes by multiplying the width and height of the box by factors each drawn from N(1,σ2s). For position noise, we add values drawn from N(0,σ2p) to the center coordinates of the face detection boxes. Note that position noise only affects the face ROI experiments. Overall we find that position noise has a smaller impact on accuracy compared to size noise. The face scale setup, where no cropping is done in pre-processing, is more robust to size noise than the face ROI setup is. Adding size noise brings a small improvement in this setting, which provides evidence that the face detector we use is not perfect.