Using the default font, which is very small and pixelated, the captcha image shows all the characters. But if I use a custom font, the captcha code doesn't always show all the characters, although it seems to have enough space. The first character is sometimes shown close to the horizontal middle of the image, and because of that not all the characters are shown. Is there another way, other than that of increasing the image's width?
Not really much of an answer, but I ran across this a long time ago: codeigniter/captcha helper/image sometimes pads too much on left