Only in modules/captcha/image_captcha/fonts: tiza.ttf
diff -ur --exclude '*~' --exclude '*#' orig-modules/captcha/image_captcha/image_captcha.admin.inc modules/captcha/image_captcha/image_captcha.admin.inc
--- orig-modules/captcha/image_captcha/image_captcha.admin.inc	2008-06-09 11:06:50.000000000 +0000
+++ modules/captcha/image_captcha/image_captcha.admin.inc	2009-04-10 19:54:01.000000000 +0000
@@ -51,6 +51,14 @@
     '#description' => t('The code length influences the size of the image. Note that larger values make the image generation more CPU intensive.'),
   );
 
+  // remove case sensitivity from test to make it easier to pass captcha
+  $form['image_captcha_code_settings']['captcha_ignore_case_sensitivity'] = array(
+    '#type' => 'checkbox',
+    '#title' => t('Ignore case sensitivity'),
+    '#description' => t('Ignore the user\'s case sensitivity in their answer. This will make it easier for users to pass CAPTCHA.'),
+    '#default_value' => variable_get('captcha_ignore_case_sensitivity', FALSE),
+  );
+  
   // font related stuff
   $form['image_captcha_font_settings'] = array(
     '#type' => 'fieldset',
Only in modules/captcha/image_captcha: image_captcha.admin.inc.orig
diff -ur --exclude '*~' --exclude '*#' orig-modules/captcha/image_captcha/image_captcha.module modules/captcha/image_captcha/image_captcha.module
--- orig-modules/captcha/image_captcha/image_captcha.module	2008-07-14 22:28:06.000000000 +0000
+++ modules/captcha/image_captcha/image_captcha.module	2009-04-10 19:54:01.000000000 +0000
@@ -149,7 +149,7 @@
 /**
  * Implementation of hook_captcha
  */
-function image_captcha_captcha($op, $captcha_type='') {
+function image_captcha_captcha($op, $captcha_type='', $response='') {
   switch ($op) {
     case 'list':
       // only offer image CAPTCHA if possible to generate an image CAPTCHA
@@ -176,6 +176,22 @@
         for ($i = 0; $i < $code_length; $i++) {
           $code .= $allowed_chars[array_rand($allowed_chars)];
         }
+		
+	// check for case sensitivity
+	if (variable_get('captcha_ignore_case_sensitivity', FALSE)) {
+          // the operator has requested the test be insensitive
+          // set the test to all lower case characters
+          $code = strtolower($code);
+	  // set a hook for the preprocessor so that the response
+	  // from the user will also be set to lower case
+          $captcha['preprocess'] = TRUE;
+	}
+	else {
+	  // reset preprocessor to FALSE 
+	  // just in case things change at runtime
+	  $captcha['preprocess'] = FALSE;
+	}
+		  
         // store the answer in $_SESSION for the image generator function (which happens in another http request)
         $seed = mt_rand();
         $_SESSION['image_captcha'][$seed] = $code;
@@ -201,6 +217,13 @@
         );
         return $result;
       }
+    case 'preprocess':
+      // this hook should only be enabled if the operator
+      // has selected case insensitivity. 
+      // it is enabled in the generate process above	  
+      if ($captcha_type == 'Image') {
+        return strtolower($response);
+      }	
     break;
   }
 }
Only in modules/captcha/image_captcha: image_captcha.module.orig