Upload Script

display.js

// see if we have a banner
<?php if (isset($this->item->banner) && [[[Component]]]Helper::checkString($this->item->banner)) : ?>
jQuery('<img src="<?php echo $this->item->banner; ?>" class="your-class-banner" alt="banner">').insertAfter(jQuery('#jform_banner').closest('.control-group'));
<?php endif; ?>

model_methods.php

	/**
	 * Works out an installation package from a HTTP upload.
	 *
	 * @return package definition or false on failure.
	 */
	protected function myUploadFunction($input)
	{
		// get the array of values
		$userfile = $input->files->get('jform', null, 'array');
		
		if (is_array($userfile))
		{
			$userfile = array_values($userfile)[0]; 
		}

		// Make sure that file uploads are enabled in php.
		if (!(bool) ini_get('file_uploads'))
		{
			JError::raiseWarning('', JText::_('Uploads are not enabled in php.'));

			return false;
		}

		// If there is no uploaded file
		if (!is_array($userfile))
		{
			return false;
		}

		// Is the PHP tmp directory missing?
		if ($userfile['error'] && ($userfile['error'] == UPLOAD_ERR_NO_TMP_DIR))
		{
			JError::raiseWarning(
				'',
				JText::_('Error')
			);

			return false;
		}

		// Is the max upload size too small in php.ini?
		if ($userfile['error'] && ($userfile['error'] == UPLOAD_ERR_INI_SIZE))
		{
			JError::raiseWarning(
				'',
				JText::_('File to large')
			);

			return false;
		}

		// Check if there was a different problem uploading the file.
		if ($userfile['error'] || $userfile['size'] < 1)
		{
			return false;
		}

		// Get classes
		jimport('joomla.filesystem.file');
		jimport('joomla.filesystem.folder');

		// Clean the name
		$userfile['name'] = JPath::clean($userfile['name']);
		
		// Build the appropriate paths.
		$config   = JFactory::getConfig();
		$tmp_dest = $config->get('tmp_path') . '/' . $userfile['name'];
		$tmp_src  = $userfile['tmp_name'];

		// Move uploaded file.
		$p_file = JFile::upload($tmp_src, $tmp_dest, false, true);

		// Was the package uploaded?
		if (!$p_file)
		{
			JError::raiseWarning('', JText::_('Upload failed!'));

			return false;
		}

		// check that this is a valid file
		$package = $this->checkUpload($userfile, $tmp_dest);

		return $package;
	}
	
	/**
	 * Check a file and verifies it as a allowed file format file
	 *
	 * @param   string  $archivename  The uploaded package filename or import directory
	 *
	 * @return  array  of elements
	 *
	 */
	protected function checkUpload($archive, $tmp_dest)
	{
		// get file format
		$fileFormat = strtolower(pathinfo($archive['name'], PATHINFO_EXTENSION));
		// get fileFormat key
		$allowedFormats = array('jpg','jpeg','png','gif');
		// check the extension
		if (!in_array($fileFormat, $allowedFormats))
		{
			// Cleanup the import files
			$this->removeFile($tmp_dest);
			$this->errorMessage = JText::_('Invalid file format.');
			return false;
		}
		
		// set directory
		$archive['full_path'] = $tmp_dest;
		
		// set format
		$archive['format'] = $fileFormat;
		
		return $archive;
	}
	
	/**
	 * Clean up temporary uploaded file
	 *
	 * @param   string  $package    Name of the uploaded file
	 *
	 * @return  boolean  True on success
	 *
	 */
	protected function removeFile($package)
	{
		// Is the package file a valid file?
		if (is_file($package))
		{
			JFile::delete($package);
		}
		elseif (is_file(JPath::clean($package)))
		{
			// It might also be just a base filename
			JFile::delete(JPath::clean($package));
		}
	}

save_method.php

		// upload the image
		if ($imageArray = $this->myUploadFunction($input))
		{
			// store the banner path to the database
			$data['banner'] = '/images/'. $imageArray['name'];

			// move the file into place
			$final_dest = JPATH_ROOT . $data['banner'];
			JFile::move($imageArray['full_path'], $final_dest);
		}