The number of resels in the image will be lower or equal to the number of pixel/voxels in the image. In an actual image the resels can vary across the image and indeed the local resolution can be expressed as "resels per pixel" (or "resels per voxel").
In functional neuroimaging analysis, an estimate of the number of resels together with random field theory is used in statistical inference. Keith Worsley has proposed an estimate for the number of resels/roughness.
- Keith J. Worsley, An unbiased estimator for the roughness of a multivariate Gaussian random field, Technical report, 2000 July.
- Keith J. Worsley, Alan C. Evans, S. Marrett, P. Neelin (1992). "A Three-Dimensional Statistical Analysis for CBF Activation Studies in Human Brain". Journal of Cerebral Blood Flow and Metabolism 12 (6): 900–918. doi:10.1038/jcbfm.1992.127.
- Waldo R. Tobler, S. Kennedy (July 1985). "Smooth multidimensional interpolation". Geographical Analysis 17 (3): 251–251. doi:10.1111/j.1538-4632.1985.tb00846.x.