App for converting image to Lego mosaic including instructions

I am looking for a developer to create an app that will convert images into Lego mosaics. I require the mosaic to be up to 48x48 in size and compatible with both iOS and Android platforms. In addition, I would like the app to have in-app purchases for Lego bricks and the ability to save mosaics as PDFs. The ideal candidate for this project should have experience in developing cross-platform apps, as well as expertise in in-app purchases and social sharing options.