A digital photo frame (also called a digital media frame) is a picture frame that displays digital photos without the need of a computer or printer. The introduction of digital photo frames predates tablet computers, which can serve the same purpose in some situations; however, digital photo frames are generally designed specifically for the stationary, aesthetic display of photographs and therefore usually provide a nicer-looking frame and a power system designed for continuous use. Digital photo frames come in a variety of different shapes and sizes with a range of features. Some may even play videos as well as display photographs. Owners can choose a digital photo frame that utilizes a WiFi connection or not, comes with cloud storage, and/or USB and SD card hub. Features Digital photo frames range in size from tiny keychain-sized units to large wall-mounted frames spanning several feet. The most common sizes range from to . Some digital photo frames can only display JPEG pictures. Most digital photo frames display the photos as a slideshow and usually with an adjustable time interval. They may also be able to send photos to a printer, or have hybrid features. Examples are the Sony S-Frame F800, that has an integrated printer on its back, or the Epson PictureMate Show. Digital photo frames typically allow the display of pictures directly from a camera's memory card, and may provide internal memory storage. Some allow users to upload pictures to the frame's memory via a USB connection, or wirelessly via Bluetooth technology. Others include support for wireless (802.11) connections or use cellular technology to transfer and share files. Some frames allow photos to be shared from a frame to another. Certain frames provide specific application support such as loading images over the Internet from RSS feeds, photo sharing sites such as Flickr, Picasa and from e-mail. Built-in speakers are common for playing video content with sound, and many frames also feature remote controls. Battery-operated units are also available for portable use. A new generation of frame companies, such as Meural, is emerging that combines larger formats, built-in access to artistic content, and innovative control mechanisms. Aspect ratio The aspect ratio of the frames can vary. Common aspect ratios include: 4:3, 3:2 and 16:9. (Sometimes 16:9 frames are actually 15:9) Depending on the model and features, images which do not exactly fit the aspect ratio of the frame may be cropped, stretched,