For watermarking image using Qimage component in cakephp first we have to  download Qimage plugin  after downloading Qimage plugin we have to put it into  App/Controller/Component .

Then we have to do all this in our controller.

    class UploadsController extends AppController {    
        public function add(){
             if ($this->request->is('post')) {
                $this->Upload->create();
             
          if ($this->request->data['Upload']['photo']!='' && is_array($this->request->data['Upload']['photo'])) {
                $imgData = array();
                $imgData['file'] = $this->request->data['Upload']['photo'];
                $imgData['name']=$this->data['Upload']['photo']['name'];
                $imgData['path'] = WWW_ROOT . '' . '/images/'; // path where the image will we copied
                
                $user_image = $this->Qimage->copy($imgData); //Qimage copy function
                
                  // Qimage watermark function,
               $this->Qimage->watermark(
	array(
		'file' => $imgData['path'].$user_image,
                'output' => WWW_ROOT. '/images/thumbnail/' 
                       // path where the image will we uploaded after getting watermark
          )
        );
            }
          else{
                $user_image = "";
          }
             
            
        }

In above code firstly we are copying our image with the help of $this->Qimage->copy(); function  in our webroot/images folder after copying we are watermarking image with the help of $this->Qimage->watermark(); function and then storing it in webroot/images/thumbnail folder.