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Image E generated from the CTF fit to micrograph #1 of set #7 of the CTF challenge. At every pixel (corresponding to a spatial frequency vector g), this image records n, the number of preceding CTF extrema (Equation 11). Here this value is color-coded, so that pixels at spatial frequencies before the first extremum of the CTF, which have value 0, are displayed in dark blue. Pixels that have 35 or more preceding CTF extrema are shown in dark red.
