PIVMat Function Reference << Prev | Next >>
filterf
Apply a spatial filter to a vector/scalar field.

Description ```FF = filterf(F,FSIZE) applies a spatial filtering of the vector/scalar field(s) F by computing its 2D convolution with a Gaussian kernel of width FSIZE (expressed in mesh units). If not specified, FSIZE=1 is taken by default. This operation filters out structures of size typically smaller than FSIZE (low-pass filter). The Gaussian kernel is defined as: G(X,Y) = exp ( -(X^2+Y^2)/(2*FSIZE^2) ) The kernel is defined in a square domain of size 1+2*CEIL(3.5*FSIZE) (i.e., for FSIZE=1, it is defined over a 9x9 matrix). The convolution is performed using Matlab's CONV2 function. FF = filterf(F,FSIZE,KERNEL) specifies the kernel G(X,Y): 'gauss': gaussian kernel (by default) 'flat': flat (or top-hat) kernel, G = ONES(FSIZE,FSIZE) (FSIZE must be an even integer) 'igauss': derivative of the integrated gaussian (minimized discretisation effects for small FSIZE). The size of the filtered field is smaller than the original field, to avoid boundary effects (the convolution is done by CONV2 with the option 'valid'). If you prefer to keep the whole field, use filterf(F,FSIZE,KERNEL,'same') Note : If there are missing data in the field, it is better to first interpolate the data. See interpf. If FSIZE is an array, applies each element of FSIZE over each element of F (one must have LENGTH(FSIZE)=LENGTH(F)). If no output argument, the result is displayed by showf. Examples v = loadvec('*.vc7'); showf(filterf(v)); showf(filterf(v,2,'flat')); showf(filterf(vec2scal(v,'rot'),2)); See Also showf, medianf, bwfilterf, addnoisef, interpf, GAUSSMAT, CONV2, tempfilterf. Published output in the Help browser showdemo filterf ```
 Previous: extractf Next: flipf

2005-2017 PIVMat Toolbox 4.10