public void pressedDecrypt() {
		String imgPath = txtImage.getText();

		if (imgPath.isEmpty()) {
			displayError("Error", "Choose an image!");
			return;
		}

		String imageSuffix = imgPath.substring(imgPath.lastIndexOf('.'), imgPath.length());
		if (!(imageSuffix.equalsIgnoreCase(".png"))) {
			displayError("Error", "Only .png is supported!");
			return;
		}

		// where to save recovered file
		File f = askForTargetFile();
		if (f == null) {
			displayError("Error", "Could not save file");
		}
		try {
			Steganography.decrypt(new File(imgPath), f);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}