Visual tasks often require a hierarchical representation of shapes and images in scales ranging from coarse to ne. A variety of linear and nonlinear smoothing techniques, such as Gaussian smoothing, anisotropic di usion, regularization, etc. , have been proposed, leading to scalespace representations. We propose a geometric smoothing method based on local curvature in shapes and images. This de...

A non-oscillatory numerical scheme based on a general solution of unsteady advection–di usion equations is presented. A general solution for initial value problems of linear two-dimensional unsteady advection–di usion equations is obtained using the spectral method. The resulting numerical scheme is explicit with respect to time, and ful lls the Patankar’s positive coe cients condition for any ...

Error di usion halftoning is a popular method of producing frequency modulated (FM) halftones. In FM halftoning the dot size and shape is xed (equal to one pixel) and the dot frequency is varied in accordance to the graylevel values of the underlying grayscale image. We generalize error di usion to produce FM halftones with user controlled dot size and shape using block quantization and a block...

We investigate the relative importance of di®usion and jumps in a new jump di®usion model for asset returns. In contrast to the standard modelling of jumps for asset returns, the jump component of our process can display ̄nite or in ̄nite activity, and ̄nite or in ̄nite variation. Empirical investigations of time series indicate that index dynamics are essentially devoid of a di®usion component, ...

A simple and robust approach is proposed for the parametric estimation of scalar homogeneous stochastic di¤erential equations. We specify a parametric class of di¤usions and estimate the parameters of interest by minimizing criteria based on the integrated squared di¤erence between kernel estimates of the drift and di¤usion functions and their parametric counterparts. The procedure does not req...

Image halftoning converts a high-resolution image to a low-resolution image, e.g. an 8-bit grayscale image to a binary image, for printing and display. Conventional error di usion halftoning produces worms and other objectionable artifacts. Tone Dependent error di usion (Li and Allebach) helps reduce these artifacts by controlling di usion of quantization errors based on the input graylevel val...

|The error di usion algorithm for digital halftoning is equivalent in form to a noise-shaping feedback coder, a class of delta-sigma modulator. The white noise assumption of the quantizer error is known to be false; in fact, the quantizer error is seen to be highly correlated with the input image. To account for this correlation, we use a gain model for the quantizer. This model accurately pred...

An alternative speci¢cation for the trend component of crop yield growth is developed and applied to maize yield data for Zimbabwe's large-scale farming sector. This accounts for permanent regime shifts as new technologies are discovered but allows gradual absorption as adoption follows a di¡usion path. Econometric methods are used to estimate the timing and importance of innovations, as well a...

Error di usion ordered dither and patterning are well known digital halftoning tech niques each with its advantages and disadvantages Error di usion is known for correlated artifacts looking like zebra stripes Images produced by ordered dither and patterning su er from arti cial contours in slowly varying regions of pictures Use of ordered matrices by both ordered dither and patterning results ...

We derive hydrodynamic equations for systems not in local thermodynamic equilibrium, that is, where the local stationary measures are \non-Gibbsian" and do not satisfy detailed balance with respect to the microscopic dynamics. As a main example we consider the driven di usive systems(DDS), such as electrical conductors in an applied eld with di usion of charge carriers. In such systems, the hyd...