Biologists and microscope experts acquire image data. Computational scientists design and implement image processing and analysis algorithms Bioimage analysis is a way of integrating these two resources and to come up with numerical interpretations of biological systems. As this is a still rapidly developing field, standardized procedure is poorly established and we have much more room to develop. Even then, we do have some general approaches that we should take. In this introduction, I will clarify some of the key aspects about investigating biological systems numerically via image data.