When uploading directly to the site, it costs 2 TBT per image. Something that can quickly drain you of hundreds of TBT depending on how often you post images. What you should instead do is upload it to an external site (I use Imgur myself) and link the photos from URL. Make sure to uncheck the box for "Retrieve remote file and reference locally" because for some reason checking it makes the file not work 90% of the time.