Image Verification: Generate and verify CAPTCHA validation images

This class can be use to generate CAPTCHA validation images and verify the text written on them.

The class can generate an image with a random text. The text is rendered using a random font, a random inclination angle and has several lines over the text to make it fuzzy. The image is generated in the JPEG format.

The verification text is stored in a session variable so the class can verify whether the validation text the user entered matches the text displayed in the image.