We would like to tell you that it is possible to retain the dimensions of the source image upon upload into the extension. 

You could following this: delete line 108 

Bss\ProductLabel\Controller\Adminhtml\Label\Save.php

$this->canResizeImage($files, $beforeImageData, $beforeImage, $labelImg, $data, $image_data);

When you have done that, please upload the image again and save it.