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The accuracy of maximum entropy reconstruction of Z-contrast STEM images has been evaluated with the effects of experimental variables and noise taken into account by the means of image simulation. As the specimen contains atom species of greatly different atomic numbers, special attention is given to the reliability of the position and composition of lighter atoms that are determined from Z-contrast images in the presence of heavier atoms. When the noise is moderate (SNR > 2.5), the position of atom columns can be measured within an accuracy of 0.03 nm. With a higher signal-to-noise ratio (SNR > 5) the composition of lighter atoms can be resolved reliably from the Z-contrast images. However, when image noise increases, the relative intensity of lighter atoms may deviate from the actual value in the specimen object function. (c) 2008 Elsevier Ltd. All rights reserved.