What is a RAW or DNG photo? Unprocessed sensor data

How does RAW capture work on a phone?

Android added RAW capture to its Camera2 interface in Android 5.0, and phones that support it can write DNG files. Samsung's Pro mode and Expert RAW app, and Pixel's camera settings, offer RAW, usually saving a JPEG and a DNG side by side for each shot. That pairing is the key storage fact: every RAW photo is really two files.

DNG stores sensor values plus metadata describing the lens and colour, so editors such as Lightroom or Snapseed can process it later.

Some phones go further with computational RAW. Samsung's Expert RAW and Google's RAW output merge several frames before writing the DNG, so the file is cleaner than a single sensor read but still unprocessed for colour and tone. These files can be larger than standard DNGs.

RAW, JPEG and HEIC compared

Phone JPEGs benefit from multi-frame processing that a single RAW frame may not include, so the JPEG often looks better straight out of the camera. Formats are compared in more depth on the JPEG and HEIC pages.

DNG is lossless or lightly compressed, so the file keeps every value the sensor recorded. That is what allows a two-stop exposure fix that would band or posterise in a JPEG.

Should you keep RAW files?

• Delete the DNG once you have edited and exported a shot, or decided not to edit it.
• Keep the DNG for photos you may print large or re-edit later, ideally on a computer or cloud folder.
• Turn RAW off for daily use. It is easy to forget it is enabled and fill storage in weeks.

For a wider plan, see phone storage full: what to do.

A quick audit: in a file manager, search the camera folder for .dng and sort by size. If you find hundreds of files you never edited, moving them to a computer or deleting them often frees more space than any other single step.

Backing up DNG files to a computer before deleting them is cheap insurance, because no app can rebuild the RAW data from the JPEG twin later.