imwr.imwd             package:wavethresh             R Documentation

_I_n_v_e_r_s_e _t_w_o-_d_i_m_e_n_s_i_o_n_a_l _d_i_s_c_r_e_t_e _w_a_v_e_l_e_t _t_r_a_n_s_f_o_r_m.

_D_e_s_c_r_i_p_t_i_o_n:

     This functions performs the reconstruction stage of Mallat's
     pyramid algorithm (i.e. the inverse discrete wavelet transform)
     for images.

_U_s_a_g_e:

     imwr.imwd(imwd, bc=imwd$bc, verbose=FALSE, ...) 

_A_r_g_u_m_e_n_t_s:

    imwd: An object of class `'imwd''. This type of object is returned
          by `'imwd''.

      bc: This argument specifies the boundary handling, it is best
          left to be the boundary handling specified by that in the
          supplied imwd (as is the default).

 verbose: If this argument is true then informative messages are
          printed detailing the computations to be performed

     ...: any other arguments

_D_e_t_a_i_l_s:

     Details of the algorithm are to be found in Mallat (1989).
     Similarly to the decomposition function, 'imwd' the inverse
     algorithm works by applying many 1D reconstruction algorithms to
     the coefficients. The filters in these 1D reconstructions are
     incorporated in the supplied 'imwd.object' and originally created
     by the 'filter.select' function in WaveThresh3.

     This function is a method for the generic function 'imwr' for
     class 'imwd.object'. It can be invoked by calling 'imwr' for an
     object of the appropriate class, or directly by calling imwr.imwd
     regardless of the class of the object.

_V_a_l_u_e:

     A matrix, of dimension determined by the original data set
     supplied to the initial decomposition (more precisely, determined
     by the 'nlevels' component of the 'imwd.object'). This matrix is
     the highest resolution level of the reconstruction. If a 'imwd'
     two-dimensional wavelet transform is followed immediately by a
     'imwr' inverse two-dimensional wavelet transform then the returned
     matrix will be exactly the same as the original image.

_R_E_L_E_A_S_E:

     Version 3.5.3 Copyright Guy Nason 1994

_S_e_e _A_l_s_o:

     'imwd', 'imwd.object', 'imwr'.

_E_x_a_m_p_l_e_s:

     #
     # Do a decomposition, then exact reconstruction
     # Look at the error
     #
     # Test image is just some sort of  square matrix whose side length
     # is a power of two.
     #
     #max( abs(imwr(imwd(test.image)) - test.image))
     # [1] 1.014611e-11

