  Using Subsurface Charge Accumulation scanning microscopy we image strips of
low compressibility corresponding to several integer Quantum Hall filling
factors. We study in detail the strips at Landau level filling factors $\nu =$
2 and 4. The observed strips appear significantly wider than predicted by
theory. We present a model accounting for the discrepancy by considering a
disorder-induced nonzero density of states in the cyclotron gap.
