Can I create Instagram-esque filters with javascript?
The images can be processed client-side or server-side(node.js)
I could overlay some pngs and box-shado
You could do it with canvas. See :
Making Image Filters with Canvas
Pixastic Image Processing Library
I ended up finding this, http://vintagejs.com/
Alex Michael has a fantastic open source javascript library for instagram filters: http://alexmic.github.com/filtrr/
I think all filters are public libs wrote in C/C++ that u can import in node =) Give a try