Convert ARW to JPG

A raw developer has to demosaic: reconstruct three colour channels from a grid where each photosite recorded one, then apply white balance, a tone curve and a colour profile. On a 61-megapixel file that is real computation, and it is why a folder of ARW files takes minutes to render thumbnails and longer to export.

This does none of it. Sony embeds a complete JPEG in the ARW at the moment of capture, and the conversion scans for it, validates it and hands it over. For a JPG target with no maximum width set, the bytes are copied out rather than decoded and encoded again — no quality spent, whatever the metadata option is set to. That is why the whole card goes through in the time a developer needs to build previews.

Sony shipped compressed raw as the only option on the early Alpha bodies, and photographers found its limits: a delta-compression scheme that could produce visible posterisation and haloing at extreme contrast boundaries — a branch against a bright sky, a specular highlight on chrome. The complaints were real enough that Sony added uncompressed raw by firmware on the A7R II, and lossless compressed later on the A1 and A7 IV generation.

It is worth knowing which mode your body is in, and it has no bearing on this conversion. The compression scheme governs how the sensor readings are packed; the embedded preview is a separate JPEG written by the camera’s processor. A compressed ARW and an uncompressed one from the same body yield the same extracted picture.

The rendering is the camera’s: the Creative Style or picture profile you had loaded, the white balance it chose, its noise reduction and sharpening. If you shot with a flat profile intending to grade later, the extracted JPEG will look flat, because that is what the camera produced.

On modern Alpha bodies the preview is the full pixel dimensions of the sensor, so a 24-megapixel A7 III gives a 6,000-pixel-wide JPEG and a 61-megapixel A7R IV gives 9,504. It is a full-size picture, not a proxy.

A desk or an agency generally wants the capture data as part of the delivery: lens, focal length, aperture, shutter speed, ISO and the exact capture time. Because the preview is passed through without a re-encode, all of it can be kept exactly as the camera wrote it — but it is not kept unless you say so. "Remove metadata" is on by default, so the JPG arrives clean.

That is the right default for the other half of the same card. Filed frames go to a desk; the rest go somewhere public, and a body paired to a phone tags location more often than people expect. So turn the option off when you are filing to somebody who needs the data, and leave it alone for everything else. Setting a maximum width was the blunt way to strip it and is now the wrong advice, since it removes the metadata only by re-encoding the picture. The ICC profile is kept in both cases, so a wide-gamut frame does not come back washed out.

The pattern this fits is triage. Extract everything, look through it, send the six frames that are wanted, and keep the ARW files for whichever of those gets used at size or needs work. Nothing is consumed by converting — the raw file is untouched and still holds the sensor data.

What the JPG cannot do is rescue an exposure. A highlight the camera clipped in its rendering is often still present in the ARW and is not present in the preview. If a frame is important and difficult, it needs a raw developer; if it is important and correctly exposed, the extracted JPEG is the same picture the developer would give you.

Nothing about ARW is readable by a browser or by most operating systems out of the box. Windows needs a codec, macOS support trails new Sony bodies, and a locked-down work laptop will not be getting Imaging Edge installed today.

This runs as JavaScript in the tab, which is precisely why it works in that situation. Plug in a card reader, drop the files, take the JPGs. It also works on a tablet, and it works with the wifi disconnected, because there is nothing for the network to do.

The extractor keeps the largest embedded JPEG above 640 by 480 and rejects anything smaller, so a file whose only preview is a thumbnail fails with a message rather than producing something useless.

In practice that happens to ARW files that did not come straight off a camera: recovered by an undelete tool, truncated by a card pulled mid-write, or written out by third-party software that did not bother with a preview. If the original card copy still exists, use it. If it does not, the file needs a decoder that reads the sensor data.

The free tier accepts input files up to 100 MB. Almost nothing in this bundle comes close — but an uncompressed 61-megapixel A7R IV or A7R V frame runs around 120 MB and does. The same frame shot in lossless compressed mode is roughly half that and converts without trouble.

That is a good argument for lossless compressed as a default on those bodies anyway: the same information, in far less space, with none of the artefacts that made the original compressed mode controversial.

The conversion is local. The ARW files are read from your disk, scanned in memory and written back as JPGs, and nothing is transmitted at any point. For an embargoed event, an unpublished commercial job, or a court or hospital assignment, uploading the card to a website is not an option and does not need to be one.

You can verify it rather than trust it: open the developer tools, watch the network tab through a conversion, or turn the connection off and convert anyway.