   Imaging correction
  Hi,I have a web cam, and I would like to know if I can perform a correction of the images from the web cam, that means a lens distortion correction, in GLSL.I would like to write vertex and fragment shader so the GPU will perform this correction, but is it possible?   
  Yes this is possible.  You don't really even need GLSL to do it if you don't want.  One good approach for removing distortion is to do a two pass system.  First render your scene normally (the planar view).  Now create a screen-sized quad that is heavily tesselated, and texture map this image onto the quad.  Now all you have to do is move the vertices to correct for the distortion, and the scene will look correct.  You can either do this statically, or each time through the vertex shader.;  Thanks for the reply!1) I do not understand why I should do 2 passes???Indeed, once I have my image, I can apply it on a quad on which I have move the vertices correctly to correct the distortion.So dispaly a first time my image is only usefull to see the kind of distortion and so apply the right move???2) How could I modify the vertices coord? Should I do it in my vertex shader, or on the CPU when I pass then to the GPU??   