In this wiki I will show how could use a Captcha in yii CForm. The easy way to show captcha image is create a form using CHtml method & CActiveForm, but CForm also should be able to show a captcha.

In your components -

Create a widget MyCaptcha.php

class MyCaptcha extends CCaptcha
{
   public $model;
   public $attribute;
                
   public function run(){
	   
       parent::run();
       echo CHtml::activeTextField($this->model, $this->attribute);
    }
}

Add this into your contoller, to show the captcha image.

public function actions()
 {
   return array(
	  'captcha'=>array(
	  'class'=>'CCaptchaAction',
	  'backColor'=>0xFFFFFF,
	 ),
   );
}

in view, your CForm like -

return array(
    'title'=>'Please provide your login credential',
 
    'elements'=>array(
        'username'=>array(
            'type'=>'text',
            'maxlength'=>32,
        ),
        'password'=>array(
            'type'=>'password',
            'maxlength'=>32,
        ),
        'verifyCode'=>array(
	          'type'=>'MyCaptcha',   //render the captcha image & text field.
              'showRefreshButton'=>false,
	          'clickableImage'=>true,
	 ),
    ),
 
    'buttons'=>array(
        'login'=>array(
            'type'=>'submit',
            'label'=>'Login',
        ),
    ),
);

Try this way it's working fine :)..