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I've be using a combination of "painting" apps on my iPad to create digital "paintings" out of my photos. I'd like to know what the digital specifications of both the initial photo AND the painting should be in order to print them on relatively large canvases (perhaps something around 24 x 36" or larger.) I was told that the apps on the iPad cause a loss of resolution in the final product but I would like to sell my images to catalogs and want them to be done properly. I now shoot with a 24 MP DSLR but a lot of my photos were shot on a 10 MP Nikon D80, I think at the finest resolution possible. Would need to double check that.