> Could you tell my what is the simplest way to display captured image on the > screen with position marked (I detect the pupil in the eye image, so I detect > pupil area using rectangle and want to draw rectangle on the image before I > draw image on the screen). Are there any libries to do this? Most applications use mitshm extension, so you capture into a shared memory block and then use that to pass it rapidly to the Xserver. Since its a pixmap you pass over you can then draw it and draw on it (ask X to draw a rectangle) I'm suprised Qt isnt doing that anyway (or maybe it has flags for it). Take a look at xawtv, its a scary program in places but it shows you how to use XShm extensions, how to use Xv (overlay) and also how to do it the hard slow way
