Moku Hanga handles high-resolution files with ease. I can even feed it Photoshop PSD and Canon RAW files with no problem. The app is supplied with presets for instant gratification, but is totally user-customizable. A set of paper backgrounds and edges fill out the app.
In the spirit of Japanese woodblock subject matter, I used a photo of a pagoda I shot in Sydney, Australia (of all places!). I did do a bit of prep work in Photoshop, using the Adaptive Wide Angle filter to eliminate camera lens distortion (see the original image below).
The best feature of Moku Hanga is the price: $7.99 (the iPhone and iPad versions are $2.99). JixiPix has several very nice image-filtering apps with highly reasonable pricing.
I have a feeling I'll be getting some more of these!