Hello sir , I am computer engineer student currently in final year and have developed a website for online purchases of printed T-shirts. The name of website is www.memarkida.com.
You can also see my progress by visiting the website mentioned above. I have gone through your requirement and I can assure you that I can build a collage maker system with photo upload, templates, collage making tools, background change options and photo removal features. Moreover, the system should have high-res download options in JPEG/PNG format including templates.
I am familiar with most of the libraries that you mentioned in your project description. Additionally I can provide full sourcecode so that you can install/integrate it on your own. I also guarantee regular work updates as well as timely responses to any queries regarding the project.
I believe that my skills and experience make me the best fit for this project - please feel free to contact me if you have any questions or would like more information about me or my work.