# fields, Tools for spatial data
# Copyright 2004-2007, Institute for Mathematics Applied Geosciences
# University Corporation for Atmospheric Research
# Licensed under the GPL -- www.gpl.org/licenses/gpl.html
"setup.image.smooth" <- function(nrow = 64, ncol = 64, 
    dx = 1, dy = 1, kernel.function = double.exp, theta = 1, 
    xwidth = nrow * dx, ywidth = ncol * dx, ...) {
    M2 <- round((nrow + xwidth/dx)/2)
    N2 <- round((ncol + ywidth/dy)/2)
    M <- 2 * M2
    N <- 2 * N2
    xi <- (0:(M2 - 1)) * dx
    xi <- xi/theta
    yi <- (0:(N2 - 1)) * dy
    yi <- yi/theta
    out <- kernel.function((matrix(xi, M2, N2)^2 + matrix(yi, 
        M2, N2, byrow = TRUE)^2), ...)/theta
    out <- cbind(out, out[, N2:1])
    out <- rbind(out, out[M2:1, ])
    list(W = fft(out)/(M * N), dx = dx, dy = dy, xwidth = xwidth, 
        ywidth = ywidth)
}