= Solution
The repeated, similarly oriented rounded triangular outlines in panel (a) are characteristic of <AFM tip convolution>: a narrow raised object can image the shape of a blunt or contaminated <AFM probe>, rather than reveal its own lateral shape. A finite tip radius broadens lateral dimensions. Replace or clean the <AFM probe>, check it on an independently characterized sharp-feature standard, and repeat at low load; agreement after a tip change is stronger evidence than a visually pleasing image. Image processing cannot uniquely recover unmeasured sidewalls or prove that every particle with a similar outline is an artefact.
Panel (b) contains horizontal streaks associated with steep features. The natural instrumental diagnosis is <AFM feedback artefact>: the height controller does not track a rapid change faithfully, or rings after it. Reduce the scan speed and adjust proportional/integral gains below the oscillation threshold. Compare trace and retrace and rotate the fast-scan direction: a streak following the scan rather than the specimen is instrumental. Loose contamination can also produce scan-line streaks, so clean or change the <AFM probe> if tuning does not remove them. \b[Tip-shape broadening in (a), and scan-direction tracking/streaking in (b), are the principal diagnoses; the images alone do not uniquely establish every underlying cause.]
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