This page will eventually describe some software I've written to automate some of the work of making seamless textures. Meanwhile, here are a few examples. These all started as my own photographs. They have some pre-processing in Photoshop for distortion, perspective correction, and removal of blemishes, and post-processing for contrast and lighting level, but the work of erasing the seams was automatic, requiring only the manual choice of a few parameters for the process.
There is a lot more to de-seaming than merely making a smooth blend of opposite edges. Blending tends to reduce contrast, and a suitable transformation must be applied to cancel the effect. Even with a perfect blend, there is often a slight gradient of colour or contrast across the whole picture, which may be imperceptible in the original picture but immediately obvious when it is tiled. This is especially true for a photograph of an iridescent or glossy material, such as brickwork. The process for automatic de-seaming first performs colour and contrast equalisation across the whole picture, then blends opposite edges, and corrects for the loss of contrast due to blending. Finally, there is an option to remove “rivers”: vertical or horizontal stripes of lighter or darker parts of the picture.