Captured Screenshots as Textures (Pseudocode needed!)

Hey folks!

So, in my game, the player must paint a series of objects (I'm doing this by recording the position of paintsplats rendered on the GUI), and at the end of the level the game is supposed to present the player with pictures of all their paintings, which I captured as .pngs or .jpgs when the player finished painting them. I'm comfortable with capturing screenshots and saving them with appropriate file names. But I don't know how to use www. or some other means to load that texture back into the program so that it can be used later as a texture. How might one do this without www.texture? And, for +30 super extra special bonus points, is there a way of capturing ONLY the gui and not everything else on the screen at the moment I'm capturing the screenshot? I would imagine that I could just render one frame with white in front of the camera, and then use a shader to re-render the white in the image as alpha so as to capture only the gui textures (which are black). But this would result in a flash of white for one frame, right? Yucky.

Save me from my ignorance! (Thanks).