Identification of the spatial location of images in 1-D, 2-D, or even 3-D situations is often a requirement from sampled and digitized images which refer to regular independent linearly distributed pixels. The high-precision evaluation of the position requires interpolation calculations between the spatial samples to obtain a precision better than the geometrical pitch of the elementary pixels. Two calculation methods are discussed to attain such a subpixel accuracy: The first one proceeds from the well-known method of calculating the "centroid" of the samples in the direct space; the second one relies on the retrieval of the Fourier phase frequency dependence in the frequency domain. Both specifications are evaluated and the specific case of a 3-D signal is discussed. Both methods are independent of the analytical model for the function.