Kaleidoscopr
The web kaleidoscopr allows you to browse through pictures from flickr.com, flip them horizontally and vertically and make combinations of these pics. Earlier it accepted any images on the web, but for security reasons it’s now limited to pictures on flickr.
To find an interesting picture you can browse through flickr’s pictures of a given day (just type in sth. like 2006-08-16), the images of some user (e.g. ctrlw), or search them by tags or description (e.g. winter). You can also select the license of pictures you search for. All searches are limited to pictures under a creative commons license, that at least allows others to modify the original image.
When you find a nice picture, just click on its thumb and then you can play around rearranging the 4 mirrored images with the links on the left. Finally, you can produce a single image using the links containing single image. Depending on the original image there may be different sizes available. The information shown below these links is taken directly from flickr, showing picture title (with a link to the original) and description, the user name and the exact license for the picture.
I found that especially nature photos give good results, since using organic structures comes close to real kaleidoscope pictures. It’s also nice to use more or less abstract photos or photos taken against the sky. The results often seem somehow spacey. On the other hand, images which already show some sort of horizontal or vertical symmetry are less useful. In normal pictures kaleidoscopr increases symmetry, but repeating symmetric pictures makes them look a bit boring.
The resulting images are put under the same license as the original. So if the original license was Attribution - ShareAlike, then you may use and distribute the kaleidoscoped image with a reference to the original author, adhering to the same or similar terms and requiring others to do the same. Have a look at the Creative Commons site to get the details.
The page is made with php, using Dan Coulter’s great phpFlickr class to browse through flickr’s pics. Selected images are cached on the server, and for the flipping php’s gd library comes in handy.