Captcha Images Plugin ~ readme / help file

This plugin creates images with scrambled letters that your visitors have to solve before they can leave a comment, or optionally get the trackback URL. It will randomly pick a random number of random letters or numbers or characters from randomly selected fonts, then make them appear randomly different, then put them on a randomly generated background.

It ships with some fonts, and you can add your own (if you want) to the qp_plugins/captcha_img_plugin/fonts/ folder.

Settings, Settings, & Settings

Use For:
  • Blog Members: If a registered user is a member of the blog they want to leave a comment on and their level is below this setting then they will have to solve your captcha. The default is 0, which means no blog member will have to solve the captcha.
  • Registered Users: If a registered user is not a member of the blog they want to leave a comment on and their level is below this setting then they will have to solve your captcha. The default is 2, which means newly registered users will have to solve your captcha. (The default level for new registered users is 1.)
Randomizer settings:
  • Timeout for keys: This is how long the captcha image lasts, in minutes. The default is 120, so someone who has to solve a captcha has 120 minutes after it was generated or it doesn't count.
  • Websafe colors: Check this box if you want to limit your captcha image to 216 "web safe" colors. You might do this to make it a little easier for visitors to solve.
  • Noise: The default for this setting is "checked". If you uncheck this your captcha images will have a grid behind them instead of 'noise'. Noise helps defeat spam-bots but also makes it harder for humans.
  • Noise factor: This is a multipler that makes it harder and harder to solve the captcha by making the background noiser and noiser. Too high and the background 'noise' will just blend into a blah, so use moderately!
  • Min chars: The minimum number of characters to use, which is kinda obvious eh? Between this and Max chars it figures out a random number of characters to ask visitors to solve.
  • Max chars: The maximum number of characters to use, which is kinda obvious eh? Between this and Min chars it figures out a random number of characters to ask visitors to solve.
  • Min font size: Another fairly obvious setting: the smallest character size your visitors will be expected to solve.
  • Max font size: Okay this is getting ridiculous! This is the largest character size your visitors will be expected to solve.
  • Max rotation: This says how "off normal" a character might be, in degrees. 180 would be completely upside-down.
  • JPEG quality: This is how nice the image appears. The lower the number the harder it is to read the exact same captcha, so be nice :)
Advanced settings:
  • Valid characters: These are all the characters that might be used in your captcha image. There is really no need to change them but isn't it nice to have more settings?
  • Case sensitive: Not really "advanced" is it? The thing is it kinda goes with "valid characters" and the plugin readme writer runs out of room for settings at 10 ;)
  • Fonts folder: Here you can define a different path, relative to the plugin folder, for where the plugin should look for your font files.
  • Post-process: You can define a process that should be run to post-process the generated image. A good example would be to use ImageMagick to further "disturb" the image. The given command must accept the image data on STDIN and output it to STDOUT. This is normally done by giving "-" (without quotes) as filename for input and output. See the example below.
    If something is received on STDERR, the post-processing is skipped, leaving the original generated image unchanged.

    The following replacements get done before executing the command:
    • %rand(X,Y)% gets replaced by a random number between X and Y.
    • %arand(list|of|strings|which are|seperated|by|pipe)% gets replaced by a random item from the list.
    • %rgb(bg)% returns the RGB value of the background (bg) color, e.g. "212,213,214" (without quotes).
    For example:
    /usr/bin/convert -swirl %rand(10,30)% -blur %rand(0,50)% -rotate %rand(0,10)% -wave %rand(1,5)%x%rand(40,120)% -background rgb(%rgb(bg)%) - -
User Settings:
  • This plugin has no user settings.
Blog Settings:
  • Comments: Like it says: do you want to use captcha images on comments left this blog? (Plugin Settings for who might be exempt takes precedence.)
  • Trackbacks: Like it says: do you want to use captcha images before someone can get a trackback URL for a post on this blog? (Plugin Settings for who might be exempt takes precedence.)
  • Contact forms: Like it says: do you want to use captcha images before someone can send a message through this blog? (Plugin Settings for who might be exempt takes precedence.)
Widget Settings:
  • This plugin has no widget settings.

More Info, Credits, & Links

More Info:
Credits:
  • Thanks to Daniel HAHLER (http://daniel.hahler.de/) for initial creation of this plugin for the b2evolution project.
  • Thanks to Bushleague Critic (http://www.bushleaguecritic.com/) for porting this to the Quam Plures project ... and making it totally awesome in the process.
  • Thanks to fedora Hosted (https://fedorahosted.org/liberation-fonts/) for the Liberation Fonts
Links:

Release History:

1.0
initial release