filter2               package:EBImage               R Documentation

_2_D _C_o_n_v_o_l_u_t_i_o_n _F_i_l_t_e_r

_D_e_s_c_r_i_p_t_i_o_n:

     2D convolution-based linear filter for images and matrix data.

_U_s_a_g_e:

       ## S4 method for signature 'Image, matrix':
       filter2(x, filter, ...)

       mkball(n, shape="step")
       mkbox(n)

_A_r_g_u_m_e_n_t_s:

       x: An object of 'Image' in Grayscale mode, a numeric  'array' or
          a 'matrix'. 

  filter: A square 'matrix' with odd dimensions.

       n: A positive integer of length 1, specifying the size (number
          of rows and columns) of the returned square matrix.

   shape: A character vector of length 1, with one of two values:
          'step' for a step function, 'ball' for a semisphere.

     ...: Further arguments.

_D_e_t_a_i_l_s:

     The convolution filter is based on 'fft' transforms. If 'x' is an
     'array', the filter is applied per frame (as to images).

_V_a_l_u_e:

     'filter2' returns a transformed object of the same class as  'x'.

     'mkball' and 'mkbox' return a square matrix that can be used for
     the 'filter' argument of 'filter2'. Its dimensions (number of rows
     and columns) are given by 'n'. For 'shape="step"', the entries of
     the matrix are the integers 0 and 1, and the 1s correspond to the
     interior of a circle of radius  'n/2' around the center element of
     the matrix. For 'shape="ball"', the non-zero elements of the
     matrix are 'z = sqrt(radius^2 - x^2 - y^2)', a parameterization of
     a semisphere.

_A_u_t_h_o_r(_s):

     Gregoire Pau, gpau@ebi.ac.uk

_S_e_e _A_l_s_o:

     ' Image, fft '

