Today, we do the same thing but we do it digitally. Using photo programs such as Apple´s iPhoto, Windows Live Photo Gallery, and Picasa, we are able to label and rate photos, enter captions, and add key words about a photo. This makes it very easy to organize and retrieve images.
While humans can enter descriptive data about the photos, there is other information, let´s call it structural or sometimes administrative metadata, which the camera that captured the photo knows about the image. For example, the moment you snap a picture, the camera embeds information into the image such as the file type (e.g. JPEG, TIFF), image resolution (3264 x 2448), date and time the image was taken, perhaps even the name of the camera and size of the file (Figure 17.2). This metadata can also be used as search criteria alongside the descriptive information you manually entered yourself.
Figure 17.2
iPhoto Metadata for Image Imported from an iPhone
Like the DVD movie example sited previously, metadata is particularly useful in video because its contents aren´t directly decipherable by computers. And since video has become a primary form of communication and expression in the 21st Century, the need to organize it and access it quickly and easily is very important. One of the first forms of metadata used in video was timecode. Timecode is a labelling system that provides a way to search and edit individual frames of video. (Timecode is discussed in more detail later in this chapter.)
As video has become digital, metadata has become an essential part of the video data stream. Metadata in the serial digital video stream contains the information about what video standard is being used, the frame rate, line count, the number and type of audio channels, and the compression and encoding system used.