All, If your an old git like me you could well have a number of negatives from pre-phone photography. I am working on a project to try to capture and convert these to regular photos - will post when complete but don’t hold your breath.
I have captured a number of negative images by illuminating them from behind and using my phone to capture them. The processing comes after that - but, if you’d like to see a positive image, not the best quality, you can take the captured image and invert it as follows.
Firstly you need to set up you iPad to invert the image by going into the Settings > Accessabilty menu and near the bottom of the list click on accessibility shortcut.
Load up your image then tap the start button three times in quick succession - et Voila your picture is inverted.
Note: you need to repeat the triple press to return to your standard image.
If you found that intriguing, and you have patience, I will post a Codea app to do this. Probably about the time Codea 5.0 is published !!!