The room-temperature modulated structure of ${\mathrm{NbTe}}_{4}$ was studied by means of scanning tunneling microscopy. In addition to a relatively weak image of the average structure and stronger contrast from the incommensurate modulation, contributions from domains of nanometer sizes were detected, which appeared with variable amplitudes. The existence of secondary modulation displacements associated with precursor effects of modulation phase transitions was suggested earlier on the basis of electron-diffraction results and their computer simulation. The current results are direct evidence of these fine-scale modulation phenomena.