File: captcha-image.php

Page Details:

Uses the value of $_SESSION['captcha'] for the image's text. That value is set in generate_captcha() in include/pear-format-html.php.

If $_SESSION['captcha'] is not set, the request is bogus, so exit without any output in order to save resources.

Rules:

• Use fonts that are fuzzy.
• Use a random font for each character.
• Have each character be a random size, start at a random vertical location and appear at random angles.
• Allow characters to sometimes overlap a little and flow a bit off the canvas.
• Use two random colors for the foreground (text and arcs).
• The foreground color must contrast with the background color.
• The foreground arc colors must be the same as the text in order to make them harder to remove.
• Some arcs will also be the background color, causing them to cut up the foreground items.
• Encourage arcs not to touch the image's edges.
• Have the arcs run from left to right as to not look like 1 or l.
• Make sure each arc crosses through most of the text.

• http://www.viebrock.ca/code/10/turing-protection
• http://lists.nyphp.org/pipermail/talk/2004-June/010218.html
• http://lists.nyphp.org/pipermail/talk/2004-July/010996.html