-blur_xy

This command is a specialization of the -blur command which convolves only in the X-Y plane; it will not blur in the depth direction. Standard variation may be independently set along the x and y axis, giving rise to horizontally or vertically oriented effects. The -display of a 100,100,100,1 volumetric star field, depicted on the left, illustrates the effect. Stars are blurred in the X-Y plane, but the Y-Z and X-Z elevations do not show any smearing in the depth direction.

The format of the command is:

-blur_xy: amplitude_x[%],amplitude_y[%],_boundary={ 0=dirichlet | 1=neumann }


• amplitude_x, aplitude_y: sets the spread of the Gaussian distribution kernel, informally the amount of blurring, along the x, and y axes. One must supply a value for each parameter; there are no defaults. If you intend to set one or another amplitude to zero, consider using -blur_x or blur_y, as appropriate.
• _boundary: chooses how to handle image edges; see "Pictures have Edges. Now What?" A zero flag (0, Dirichlet) assumes that off-image pixels are black. A unit flag (1, Neumann) assumes that off-image pixels have the exact same value as the nearest edge pixel. Neumann does not exhibit a black vignette, but sometimes edge values become uncommonly bright. This value may be omitted and when it is, the command uses the Neumann policy as a default.

Garry Osgood