Convert physical coordinates to pixel coordinates
c_ijkpos(xyz, origin, voxdims, dims, clamp = FALSE)Nx3 integer matrix of pixel coordinates
Nx3 matrix of physical coordinates
Numeric: 3d coordinates of the origin
Numeric: 3 numbers describing the voxel dimensions
Integer dimensions of the 3d image array
Logical: whether or not to clamp values within the pixel boundaries of the image.