Gaze-contingent interfaces must provide adequate peripheral information to the viewer to preserve perceptual fidelity. specifically, it has been shown that preattentive (or preview) benefit must be preserved so that scene perception is not disrupted. In this paper we review recent attempts at peripheral degradation of digital imagery. We suggest that to be successful such degradation must preserve potential future visual attractors and, furthermore, not introduce artificial ones. We present a simple multiresolution image processing approach that can be utilized for this purpose. The feasibility of gaze-contingent processing has recently been questioned. In their paper, Stelmach and Tam processed images by low-pass filtering, effectively smoothing extrafoveal regions. The authors then quantized DCT coefficients in the periphery, introducing blocking artifacts. In our paper, we simulate these results and claim that neither of these methods is suitable for GC interfaces. Alternatively, we implement a simple multiple region of interest (ROI) multiresolution scheme in an attempt to degrade the periphery while preserving attentional cues. We evaluate three variants of this approach: a linear degradation function, a nonlinear function, and a function matching human visual system (HVS) acuity. The HVS-matching multiple-ROI algorithm gives good compression and alleviates the degradation of potential visual attractors. Furthermore, MIP mapping offers efficient implementation of the algorithm, making it a good candidate for gaze-contingent applications.
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