A new feature has been rolled to all Twitter users recently: You can now upload image directly to Twitter, instead of using third party services.
All the images are stored along with the tweet. Once the tweet is deleted, the images uploaded with those tweets will also be deleted.
Twitter is also going to roll out Galleries like feature soon. Know more about Image Upload
1. You can upload image which is less than or equal to 3MB in size.
2. Images are hosted at Photobucket, a well-known Twitter partner.
3. If you have protected account, then your images will not be shown in the search results. Same rule applies to the images as that of tweets from protected accounts.