Accepting a postdoc position (in a different field) after industry
As far as I know, there no specific field for postdoctoral researchers. A project may require experts in different fields, where machine learning, image processing are highly needed in interdisciplinary fields (e.g., medical image processing). 

In my opinion, you should respond to these questions before accepting the offer: 


Are you an expert in the domain of the position (regardless of the boss's field) and do you fulfil its requirements?
It is important to note that as a postdoc, you will be responsible for your work and you won't be supervised in terms of your knowledge. 
Does this intersect with your PhD in terms of research domain? 
Usually, researchers do not know their exact subdomain based on their PhDs (which is more likely to be in several subdomains). For example, working in Imaging and Robotics can be considered as "Image processing", "Machine learning", "Artificial intelligence", "Pattern recognition", etc. I would say, any position in one of these fields will be accepted for postdoc and thus will define more the research path in the next years. 


If you take a look at the research interests of any senior researcher over time, you will find slight changes. 

I am also doing my postdoc in your field, but it is totally different from what I have done during my PhD. However, I could find a common subdomain between the two experiences and I decided to continue in this direction for the next years.