Printy is a cute little app that will turn anything you take a photo of into a coloring page that can be printed on real paper and colored with real crayons. It's is incredibly easy to use and does an equally incredible job at producing colorable PDFs.
There's literally only four screens included with Printy. The first one let's you choose between taking a photo or choosing one from your Camera Roll. In the next screen, you move and scale your photo to fit in the square. Yes, you must crop your photo to square.
Once you accept your crop, you'll be shown the first draft of your coloring page. There are two sliders you can adjust to make it look better. The first slider controls the thickness of the black lines and the second slider controls the darkness of the image.
Once it looks best, tap the checkmark to generate the final high resolution image. You should notice that the lines smooth out and look better than in the previous screen. You can then choose to print the image to an AirPrint compatible printer or email it has a high resolution PDF. Here's an example of a PDF created by Printy.
My only real complaint is that once you print or email the image, you can't save it anywhere. At the very least, you should be able to save it to our Camera Roll, but even better would be if you could export to a folder in Dropbox dedicated to Printy PDF files.
I am very impressed with how well Printy works. Now, if you try to take photos of things that aren't flat or that have have too much detail, the results will not be as great. But keeping in mind that the purpose of Printy is to create coloring pages, probably for a child, you wouldn't be taking photos of these types of things anyway. I anticipate that my daughter will want me to take photos of characters in her books when she gets to the coloring age as well as use screenshots from her favorite apps and books on the iPad.