TIFF is a container format (a “file system in a file”) for images with tagged data. For example, it can contain different channels of data, or high and low resolution versions, or multiple pages of a fax document. Often the data will be JPEG-encoded. JPEG is an image codec and will often occur within some other container format but can also occur on its own as a JPG image file. EXIF metadata is stored using a TIFF-like structure, either within a TIFF file or within a block inside a JPEG image. Most camera RAW files (such as NEF, CR2, DNG etc.) are actually just a TIFF file with a different extension, with regular EXIF data, the actual raw sensor data, plus a JPEG version of the same image.

CatDV has a TIFF/EXIF parser and can therefore import RAW files, extract the JPEG version and display this using its existing QuickTime media library.