I’m happy to find you in the distant year 2025 with the same problem, I’m currently working on a real-time rendered animation of hand-drawn sequence frames, and likewise I’m in need of a very large specification for png import and extraction, and was wondering if you’ve solved this problem in the intervening years? Looking forward to hearing from you, if the problem has been solved with you I would even be willing to invite to join my project team and pay accordingly!