Update

Since I had some time and wanted to try some ideas, I've updated the Picturevert app with some new features - so now it's capable of:

• Selecting any image from the photo gallery.
• Taking an instant photo and applying effects sto it immediately.
• Inverting image colors with a variable degree of color shift.
• Making a multi-direction color trail from any point of picture with varied jitter and thickness.
• Mirroring halves of the picture in 4 directions.
• Exporting the result by using standard sharing mechanism.

Most fun was to implement color "smudge", since I wanted to make lines of variable width but with averaged color, and also with some jitter of starting point. Given that image comes as a list of values for pixels, but each pixel is actually 3 elements in array (RGB), that required some thinking.

Mirroring was fun too, because it wasn't just reversing half of the list - had to be done for each line and in iterations of 3 (because RGB).

Results

• App page with store links
• Code on GitHub