CAPTCHA by Anchal: Generate and validate CAPTCHA images

This class can be used to generate and validate CAPTCHA validation images.

It can generate an image with a text string with a variable length of a set of allowed characters.

The class generates an image with the generated text obfuscated by noise text or grid lines.

The generated image is stored in a JPEG format file created in a temporary server directory.

The class can also validated whether the text entered by the user corresponds to the text displayed in the image.