Video files, raster and vector images, raw camera images and documents can contain meta information labeled as Thumbnail Image. In some instances, the metadata can also be found in files of another type as long as they contain image data that can be represented as a thumbnail.
In the case of images, the thumbnail image contains a miniature version of the actual image. For videos, a still image from the video stream is usually used. When it comes to documents, however, the first page is typically represented in an image format to be used as a thumbnail.
The values given for the Thumbnail Image are structured in a specific way. The first part denotes the kind of data that makes up the Thumbnail Image. Usually, it’s binary data. The second part indicates the actual size of the thumbnail in bytes.