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Abstract

Much research has gone into developing methods for enhancing the contrast of
displayed 3D scenes. In the
current study, we investigated the perceptual impact of an algorithm recently
proposed by Ritschel et al.1 that
provides a general technique for enhancing the perceived contrast in
synthesized scenes. Their algorithm extends
traditional image-based Unsharp Masking to a 3D scene, achieving a
scene-coherent enhancement. We conducted
a standardized perceptual experiment to test the proposition that a 3D unsharp
enhanced scene was superior to
the original scene in terms of perceived contrast and preference. Furthermore,
the impact of different settings
of the algorithm’s main parameters enhancement-strength (¸) and gradient size
(¾) were studied in order to
provide an estimate of a reasonable parameter space for the method. All
participants preferred a clearly visible
enhancement over the original, non-enhanced scenes and the setting for
objectionable enhancement was far
above the preferred settings. The effect of the gradient size ¾ was negligible.
The general pattern found for
the parameters provides a useful guideline for designers when making use of 3D
Unsharp Masking: as a rule of
thumb they can easily determine the strength for which they start to perceive
an enhancement and use twice
this value for a good effect. Since the value for objectionable results was
twice as large again, artifacts should
not impose restrictions on the applicability of this rule.