Python vs Matlab? Which one better for image processing?
[EDIT-20200516: see at the bottom fro comparison with...cars] For learning from scratch, I would not suggest a programming language alone, but instead the couple "teaching materials" (book, lecture notes) + "exercices with a specific  programming language". So if you find a book that you like on "Python for computer vision with exercices" or "Image processing theory and practice with Matlab, that could be interesting starting points.
Also, your programming tastes and skills may evolve, and learning a first programming language helps you learning a second one in general. But laziness sometimes drives you to sticking to your first language, reusing old  librairies.
Last, the purpose is important. In my case, I mostly engineer algorithms as prototypes and proofs of concepts, that can stay as them, or are turned into "solid programs" by people that are better at, and like better, programming with the rules-of-art in lower levels languages, depending on the target.

To that respect, Matlab is great at designing and fine tuning algorithms, possesses a lot of documentation and help that you can follow step-by-step, and enjoys a long list of contributed toolboxes, esp. at MatlabCentral FileExchange.  When the workflow is set, if you care of speed, efficiency, etc., it is time to pass the algorithmic prototyping over to real programmers (C++, or lower level, which I can't do).

Python now has a large community, and has developed toolsets like Scikit-Image, and there is a tutorial for instance at Scikit-image: image processing. 
It is also interfaced with OpenCV.

Globally, as long as you grow solid image processing skills, I would think what mostly differ between Matlab and Python are the cost and the trendiness.  On my side, I would switch to Python for machine learning and data science, but I will stick to Matlab for most of my signal processing and image analysis works for a while. 

You can also use (free) open source software, with contributed toolboxes and plugins, that often benefit from external publications. I would suggest:


ImageJ: Image Processing and Analysis in Java
Icy: Open Source Image Processing Software
OpenCV: Open Source Computer Vision Library 
SciLab: Image Processing &amp; Computer Vision
Julia: Image Processing


For comparisons:


From MathWorks (biased): MATLAB vs. Python: Top Reasons to Choose MATLAB
For RealPython (biased): MATLAB vs Python: Why and How to Make the Switch
Toby Driscoll (more balanced): Matlab vs. Julia vs. Python (compared to BMW sedan, Ford pickup and Testa)



  MATLAB [...] It’s probably still the easiest to learn for basic
  numerical tasks. Meticulous documentation and decades of contributed
  learning tools definitely matter.
  
  MATLAB is the BMW sedan of the scientific computing world. It’s
  expensive [...]  rock-solid [...] attracts a disproportionate amount
  of hate.
  
  Python is a Ford pickup. It’s ubiquitous and beloved by many (in the
  USA). It can do everything you want, and it’s built to do some things
  that other vehicles can’t. Chances are you’re going to want to borrow
  one now and then. But it doesn’t offer a great pure driving
  experience.
  
  Julia is a Tesla. It’s built with an audacious goal of changing the
  future, and it might. It may also become just a footnote. But in the
  meantime you’ll get where you are going in style, and with power to
  spare.