Raster Image Formats

Raster image formats include JPEG, PNG, GIF, TIFF and RAW. Each format balances file size, quality and features, so the right choice depends on how the image will be used.

Format	Compression	Key feature
JPEG	Lossy	Small files; no transparency
PNG	Lossless	Supports transparency
TIFF	Uncompressed	Keeps all image data for high-quality printing
RAW	Uncompressed	Large files from professional cameras, good for editing
GIF	Heavily compressed	Holds multiple frames for simple animation

JPEG uses lossy compression and gives small files, which is useful for a sports-day photo you attach to an email. It does not support transparency. PNG uses lossless compression and supports transparency, so a cut-out photo of a badminton shuttlecock can sit over a poster for the school club without a pale rectangle behind it.

TIFF is uncompressed and keeps all the image data, making it suitable for high-quality printing, such as a scanned pressed-leaf collection where the faint veins must be kept before it is printed for a nature display. RAW is also uncompressed and is used by professional cameras; files are large, but they are good for editing, letting a photographer brighten a dark photo of an owl. GIF is heavily compressed and can hold multiple frames for simple animation, like a looping arrow on a classroom slide. It is now largely obsolete except for those simple animations.

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