Visual Attention

1. Visual Attention • More information in visual field than we can process at a given moment • Solutions • Shifts of Visual Attention related to eye movements • Some targets “pop-out”

2. Visual Search • Feature Integration Theory (Ann Treisman) • Parallel pre-attentive stage • Parallel feature detection modules (e.g. intensity, color, orientation) • Feature maps for each module • Feature maps combinations  Salience Map

3. Attention Control • Two Mechanisms • Bottom-up • Biases the observer towards selecting stimuli based on their saliency • Importance of unexpected • Feature maps calculated based on differences to neighbors (human eye) • Top-down • directs the “spotlight of attention” under cognitive, volitional control • Importance of desired • Use of prior information (knowledge)

4. Integration of Motion • Motion is of fundamental importance in biological vision systems • Contributes to visual attention as confirmed by Watanabe et al. • Weighted summation of the feature maps • Attending only the moving objects.

5. Integration of Prior Knowledge (top-down) • Draw attention to regions with specific characteristics(e.g. human faces) • Generate a feature map based on skin activation • Link it with the rest of the maps

6. Computational Model (Itti & Koch)

7. Demonstrative Results Skin Map Intensity Map • Possible Regions of Interest: • Hands • Head • Shoulders Color Map Orientation Map Motion Map

8. Itti & Koch map Equally Weighted maps Motion Map Motion & Skin biased May attend only the moving objects!