  We analyse observations of the X9.3 solar flare (SOL2017-09-06T11:53)
observed by SDO/HMI and Hinode/SOT. Our aim is to learn about the nature of the
HMI pseudocontinuum Ic used as a proxy for the white-light continuum. From
model atmospheres retrieved by an inversion code applied to the Stokes profiles
observed by the Hinode satellite we synthesise profiles of the FeI 617.3 nm
line and compare them to HMI observations. Based on a pixel-by-pixel comparison
we show that the value of Ic represents the continuum level well in quiet-Sun
regions only. In magnetised regions it suffers from a simplistic algorithm that
is applied to a complex line shape. During this flare both instruments also
registered emission profiles in the flare ribbons. Such emission profiles are
poorly represented by the six spectral points of HMI, the used algorithm does
not account for emission profiles in general, and thus the derived
pseudocontinuum intensity does not approximate the continuum value properly.
