remove a cpatcha code case sensitivity

for working a captcha case sensitive you will have to do following changes in following file

file

/catalog/contact_us.php

line number 81

 if ( isset($_POST['visual_verify_code']) && tep_not_null($_POST['visual_verify_code']) && 
         isset($code_array['code']) &&  tep_not_null($code_array['code']) && 
         strcmp($_POST['visual_verify_code'], $code_array['code']) == 0)

replace this code by following code

 if ( isset($_POST['visual_verify_code']) && tep_not_null($_POST['visual_verify_code']) && 
         isset($code_array['code']) &&  tep_not_null($code_array['code']) && 
         strcmp(mb_strtolower($_POST['visual_verify_code']), mb_strtolower($code_array['code'])) == 0)