Made a negative to positive inversion app

Hi guys, I’m a software engineer with a passion for film photography. I made a simple inversion app (with some basic color correction features). You can find it at negatron.yaf.et I simply hated the tools that are available (they’re either expensive or not straightforward to use) so I made this. I need your feedback, it’s still work in progress but why not share now and incorporate the fixes people need. Thank you