Magento 2 allow you to add custom field form as type image , for example when you click in edit link inisde grid you have edit page you can add from fiedl :

 
$fieldset->addField(
'image',
'image',
[
'title' => __('Image'),
'label' => __('Image'),
'name' => 'image',
'note' => 'Allow image type: jpg, jpeg, gif, png',
]
);
 

So now you have your field , you can use your controller to save the image inside media , now inject (\Magento\Framework\Image\AdapterFactory $adapterFactory,\Magento\MediaStorage\Model\File\UploaderFactory $uploader):

 
/**
* @var \Magento\Framework\Image\AdapterFactory
*/
protected $adapterFactory;
/**
* @var \Magento\MediaStorage\Model\File\UploaderFactory
*/
protected $uploader;
/**
* @var \Magento\Framework\Filesystem
*/
protected $filesystem;
/**
* @var \Magento\Framework\Stdlib\DateTime\TimezoneInterface
*/
protected $timezoneInterface;
public function __construct(Action\Context $context,\Magento\Framework\Image\AdapterFactory $adapterFactory,\Magento\MediaStorage\Model\File\UploaderFactory $uploader,\Magento\Framework\Filesystem $filesystem)
{
$this->adapterFactory = $adapterFactory;
$this->uploader = $uploader;
$this->filesystem = $filesystem;
parent::__construct($context);
}
 

 
/**
* Save action
*
* @return \Magento\Framework\Controller\ResultInterface
*/
public function execute()
{
…............
//start block upload image
if (isset($_FILES['image']) && isset($_FILES['image']['name']) && strlen($_FILES['image']['name'])) {
/*
* Save image upload
*/
try {
$base_media_path = 'ibnab/owlsliders/images';
$uploader = $this->uploader->create(
['fileId' => 'image']
);
$uploader->setAllowedExtensions(['jpg', 'jpeg', 'gif', 'png']);
$imageAdapter = $this->adapterFactory->create();
$uploader->addValidateCallback('image', $imageAdapter, 'validateUploadFile');
$uploader->setAllowRenameFiles(true);
$uploader->setFilesDispersion(true);
$mediaDirectory = $this->filesystem->getDirectoryRead(\Magento\Framework\App\Filesystem\DirectoryList::MEDIA);
$result = $uploader->save(
$mediaDirectory->getAbsolutePath(base_media_path)
);
$data['image'] = base_media_path.$result['file'];
} catch (\Exception $e) {
if ($e->getCode() == 0) {
$this->messageManager->addError($e->getMessage());
}
}
} else {
if (isset($data['image']) && isset($data['image']['value'])) {
if (isset($data['image']['delete'])) {
$data['image'] = null;
$data['delete_image'] = true;
} elseif (isset($data['image']['value'])) {
$data['image'] = $data['image']['value'];
} else {
$data['image'] = null;
}
}
}
//end block upload image
…................
}
 

with simple code you upload the image and you try if delete is checked (if true it will be deleted)