I've installed captcha_ttf v2.9 on a fairly basic zen-cart 1.3.8a installation and it almost works, except the image is always blank.

I've read through this thread (49 pages!) and I see lots of other people with the same problem, but none of the solutions work for me.

I've tried removing all backup files, disabling .htaccess temporarily (I'm not using SEO or any other mods), disabling SSL temporarily, checking for extra lines and spaces, checking that the fonts file is found and so on. There are no errors in the log. I'm on PHP v5.2.6 (Zend 2.2.0) in "apache" mode.

There's one interesting thing I don't understand - if I run captcha_test.php then right-click on the blank image and view it using IrfanView (for example) I can see the image. But that only works in jpeg mode - in png or gif mode I get "invalid header". The image never displays in firefox or IE (latest versions).

My captcha_test with the above symptoms can be seen at http://skeptic.org.uk/inquirer/captcha_test.php if that helps. (The captcha in the main store is disabled for obvious reasons.)
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Phil McKerracher
www.mckerracher.net