Mesh warping lets you distort specific areas of your image without affecting other areas. It can be used for dramatic warping effects or for more subtle focused retouching of facial features.
Mesh Warp provides a flexible mesh grid which can warp your image by repositioning the grid's lines, nodes, and patches; underlying pixels are transformed under the line, node or patch. The extent of warping you want to carry out is governed by the complexity of the grid.
You'll initially start with a mesh grid without lines, but adding your own lines and nodes lets you warp with ease. Position lines adjacent to areas in your image that you want to apply warping to.