src/File/IsImage.php
public function isValid($value, $file = null)
    {
        if ($this->allowEmpty && $this->isFileEmpty($value, $file)) {
            return true;
        }

        return parent::isValid($value, $file);
    }
public function isValid($value, $file = null)
    {
        if ($this->allowEmpty && $this->isFileEmpty($value, $file)) {
            return true;
        }

        return parent::isValid($value, $file);
    }
public function isValid ( $ value , $ file = null ) { if ( $ this -> allowEmpty && $ this -> isFileEmpty ( $ value , $ file ) ) { return true ; } return parent :: isValid ( $ value , $ file ) ; }
Returns true if and only if the file input is an image.

@param string|array $value Real file to check.
@param array        $file  File data from {@link \Zend\File\Transfer\Transfer} (optional).

@return bool
Returns true if and only if the file input is an image .