The present invention provides a method and apparatus for high precision image metrology. A feature dimension from the image is determined by measuring corresponding features in the Fourier power spectrum of the image with substantially improved precision due to immunity from noise and system response. Operationally, a digital image of the sample is acquired at sufficient resolution to capture the feature of interest. A sample widow is chosen which substantially isolates the feature of interest. The feature window is then piecewise extended to a predetermined window size for effective Fourier Transform interpolation. A Fourier Power Spectrum of the sample widow is generated at high sample density such that the loci of extremal points indicative of a feature dimension is identified with high precision. The relative spacing of the extremal points is measured and related to the desired feature dimension. Utilizing the power spectrum of the image feature in the manner herein disclosed advantageously provides a way to measure feature dimensions with high precision. The method of the present invention is substantially independent of variations in image system performance, typical system noise and sample optical properties.