(a) C/N plane at HN=6.28 ppm from the HNCO spectrum of ubiquitin recorded on a 500 MHz spectrometer, as calculated from radial spokes at 4.5°, 45° and 85.5° by a hypercomplex Fourier transform. Note that the hypercomplex transform supplied with data for the +tx +ty quadrant automatically produces the symmetric ridges one would expect using a complex transform with data for both the +tx +ty and +tx −ty quadrants. (b) C/N plane at HN=8.54 ppm from the HNCO spectrum of ubiquitin recorded at 600 MHz, calculated in subpanel (1) from 18 radial spokes with artificially added noise, in (2) from 18 radial spokes with the natural experimental noise, and in (3) from a subset of 6 out of the 18 radial spokes, in all cases by a hypercomplex transform. Panel (a) is reprinted from [14]. Panel (b) is reprinted, with permission, from [75] (© 2006 Springer).