Poisson image editing: an insert without a seam
In July 2003 at SIGGRAPH Patrick Pérez, Michel Gangnet and Andrew Blake of Microsoft Research in Cambridge showed how to paste part of one image into another with no visible seam: solve a Poisson equation that takes brightness changes from the source and values from the boundary.
Why it matters
Collage stopped being cutting and gluing: the insert takes on the lighting and colour of its surroundings, and the same solver changes texture, lighting or colour inside a chosen region. Poisson blending became the standard final step; the scene completions of 2007, among others, were stitched with it.
ACM Transactions on Graphics 22(3), pages 313-318. The equation with Dirichlet conditions on the boundary is solved for each colour channel separately; its solution is the function whose gradient is closest in L2 to a guidance field. The paper’s tools are seamless cloning, insertion of transparent objects, changes of texture, lighting and colour, and seamless tiling. The paper itself notes that Photoshop 7’s Healing Brush (2002) already achieved seamless cloning with an unpublished technique, and that the authors do not know whether it solves the same equation. The record therefore claims the first published formulation, not the first implementation.