Which is the most suitable programming language for image processing in scientific researches?
Your question as is has a very simple answer: "the best language is the one I use". Pros and Cons (P&amp;C) would give some more value to it, as commented by Peter and Marcus. So, back to the topic, but concerning with P&amp;C, here is my $\epsilon$... 

Your application does not seem to be restrict only to simulation, but also to web interface; moreover, you want a roadmap to it, probably in a asynchronous way dealing with branches, and therefore with some version control.

Matlab can be a choice if your audience has all toolboxes you have for this work (web + image + signal + ... ). Does it? 

Forget control versioning if you intend to use Simulink.

I would make thumbs up for Python as well. You have support of a huge community. The scientific packages are numerous. It is a complete language, from web applications to visual to scripting to ... And it is free!