I suggest WSxM, a powerful free software that can directly open a wide range of files format from different microscopy equipments. I has many filters and options to enhance your images. You can get it here:
You can try Gwyddion free software it is a modular program for SPM (scanning probe microscopy) data visualization and analysis. Primarily it is intended for the analysis of height fields obtained by scanning probe microscopy techniques (AFM, MFM, STM, SNOM/NSOM) and it supports a lot of SPM data formats; more details and downloading information in the following link;