private void openFile() {
		JFileChooser chooser = new JFileChooser();
		int choice = chooser.showOpenDialog(null);
		if (choice == JFileChooser.APPROVE_OPTION) {
			try {
				currentFile = chooser.getSelectedFile();
				newFile();
				MainImagePanel mip = MainImagePanel.getInstance();
				currentFile = chooser.getSelectedFile();	//store info about the file opened
				mip.setLayer(ImageIO.read(currentFile));
				mip.updateCombinedImage();
			} catch (IOException e) {
				System.out.println("Error opening file.");
			}
		}
	}