code: public function executeResize()
  	{
  		$image = $this->prepareImage();
  		$resizeConfig = $this->prepareResizeConfig();
  
  		if (!System::getContainer()->getParameter('contao.image.bypass_cache')
  			&& $this->getTargetPath()
  			&& !$this->getForceOverride()
  			&& file_exists($this->strRootDir . '/' . $this->getTargetPath())
  			&& $this->fileObj->mtime <= filemtime($this->strRootDir . '/' . $this->getTargetPath())
  		) {
  			// HOOK: add custom logic
  			if (isset($GLOBALS['TL_HOOKS']['executeResize']) && \is_array($GLOBALS['TL_HOOKS']['executeResize']))
  			{
  				foreach ($GLOBALS['TL_HOOKS']['executeResize'] as $callback)
  				{
  					$return = System::importStatic($callback[0])->{$callback[1]}($this);
  
  					if (\is_string($return))
  					{
  						$this->resizedPath = System::urlEncode($return);
  
  						return $this;
  					}
  				}
  			}
  
  			$this->resizedPath = System::urlEncode($this->getTargetPath());
  
  			return $this;
  		}
  
  		$image = System::getContainer()
  			->get('contao.image.resizer')
  			->resize(
  				$image,
  				$resizeConfig,
  				(new ResizeOptions())
  					->setImagineOptions(System::getContainer()->getParameter('contao.image.imagine_options'))
  					->setTargetPath($this->targetPath ? $this->strRootDir . '/' . $this->targetPath : null)
  					->setBypassCache(System::getContainer()->getParameter('contao.image.bypass_cache'))
  			)
  		;
  
  		$this->resizedPath = $image->getUrl($this->strRootDir);
  
  		return $this;
  	}
docs: Resize the image
  
  @return $this The image object