the 301 redirects does not affect SEO. It can be slower than accessing the file system directly but it allows to check the permissions and workflow step by Kentico and manage cache of this image by Kentico. However, if you want to use the direct file paths, you can link an image directly (without using CMS) or use media files (Media library settings
) and set up:
Use permanent URLs: unchecked
Then it will use the physical paths of media files. Please be aware that these links do not check the permissions and if you move the file, the link will be invalid. The permanent URLs work even if you move the file.