Clonación de perspectiva [Gimp]

Hace un par de años descubrí la herramienta de clonado en perspectiva para el programa de retoque digital fotográfico Gimp. Pedro Alonso, su creador, lo explicaba en su web (www.pedroalonso.net):


Google Summer of Code 2006 Participant, Google Inc. Developing the Perspective Clone tool, available by default in the kernel of GIMP 2.4. One of 630 student participants selected out of over 3000 applicants to the program.


Worked with mentor from project GIMP to develop a tool that allows cloning surfaces taking into account the perspective of the image, which is previously specified by the user. This project has been developed using C with GObject framework to use OOP. GTK+ library has been used for the graphical interface.
http://code.google.com/soc/2006/gimp/about.html
http://code.google.com/soc/2006/gimp/appinfo.html?csaid=ED4B073684AEAF2A

Para los que hacemos retoque fotográfico, esta herramienta es realmente útil. Las dimensiones de un objeto clonado en una imagen en perspectiva siempre van a ser diferentes de como debieran, con esta herramienta y estableciendo el plano contenedor se puede clonar el objeto correctamente redimensionado.
The steps to implement that tool would be:
1. Obtain the transform matrix that is defined by the user in a similar way that they do via perspective tool.
2. Use the matrix to perform the distortion step when the user paints in the image, so the perspective is preserved.

Aunque viendo el vídeo explicativo se entiende mucho mejor: