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A motion sequence may be represented as a single pattern in x-y-t space; a velocity of motion corresponds to a three-dimensional orientation in this space. Motion sinformation can be extracted by a system that responds to the oriented spatiotemporal energy. We discuss a class of models for human motion mechanisms in which the first stage consists of linear(More)
When a moving grating is viewed through an aperture , only motion orthogonal to its bars i s visible, as motion parallel to the bars causes n o change in the stimulus. Because there is a f a m i l y of physical motions of various directions and speeds that appear identical, the motion of t h e grating is ambiguous. In contrast, when t w o crossed moving(More)
Oriented lters are useful in many early vision and image processing tasks. One often needs to apply the same lter, rotated to diierent angles under adaptive control, or wishes to calculate the lter response at various orientations. We present an eecient architecture to synthesize lters of arbitrary orientations from linear combinations of basis lters,(More)
In the preceding two companion articles we studied the conditions under which transparent motion perception occurs through psychophysical experiments, and investigated the underlining neural mechanisms through physiological recordings. The main finding of our perceptual experiments was that whenever a display has finely balanced motion signals in all local(More)
The pattern of local image velocities on the retina encodes important environmental information. Although humans are generally able to extract this information, they can easily be deceived into seeing incorrect velocities. We show that these 'illusions' arise naturally in a system that attempts to estimate local image velocity. We formulated a model of(More)
The intrinsic image decomposition aims to retrieve “intrinsic” properties of an image, such as shading and reflectance. To make it possible to quantitatively compare different approaches to this problem in realistic settings, we present a ground-truth dataset of intrinsic image decompositions for a variety of real-world objects. For each(More)
Orthogonal wavelet transforms have recently become a popular representation for multi-scale signal and image analysis. One of the major drawbacks of these representations is their lack of translation invariance: the content of wavelet subbands is unstable under translations of the input signal. Wavelet transforms are also unstable with respect to dilations(More)
We describe a system for representing moving images with sets of overlapping layers. Each layer contains an intensity map that defines the additive values of each pixel, along with an alpha map that serves as a mask indicating the transparency. The layers are ordered in depth and they occlude each other in accord with the rules of compositing. Velocity maps(More)