Digimizer is described as 'Easy-to-use, flexible image analysis software package that allows precise measurements, and automatic object detection' and is an app. There are 2 alternatives to Digimizer for Mac, Windows and Linux. The best Digimizer alternative is ImageJ, which is both free and Open Source.
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.
Fiji is an image processing package—a "batteries-included" distribution of ImageJ, bundling a lot of plugins which facilitate scientific image analysis.
