SPIP™ is described as 'is the preferred software package for nano- and microscale image processing at high-tech companies and leading research institutes in more than 61 countries'. There are three alternatives to SPIP™ for Windows, Linux and Mac. The best alternative is ImageJ, which is both free and Open Source. Other great apps like SPIP™ are OLYMPUS Stream (Paid) and MountainsMap (Paid).
ImageJ is a public domain, Java-based image processing program developed at the National Institutes of Health. ImageJ was designed with an open architecture that provides extensibility via Java plugins and recordable macros.