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ARW
What is an ARW file?
Sony raw capture from Alpha bodies.
What ARW is
ARW is a container: a wrapper that holds streams encoded by something else. It stores a grid of pixels, so enlarging it past its own resolution softens it. It is used for photography and editing.
The extension is .arw, and the full name is Sony Alpha Raw. Both matter less than what the file can hold, which is what the rest of this page is about.
Where ARW came from
Sony published it in 2005. It comes out of Sony Alpha bodies bodies.
Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.
The specification belongs to its vendor
Reading it outside the vendor’s own software depends on work done by other people, usually by inspection rather than by documentation. That mostly works and occasionally does not, which is the reason to convert anything you intend to keep.
Nothing is thrown away
ARW stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.
It cannot be transparent
ARW has nowhere to record transparency. Anything transparent in the source is filled with a solid colour on the way in — white, unless something chooses otherwise.
Colour it can describe
Up to 14 bits per channel. It can work in RGB.
More than eight bits per channel is what stops a gradient from stepping when it is edited, which is why it matters in a working file and rarely in a finished one.
What opens ARW
Adobe Lightroom, Capture One and darktable read it, and so do most programs of the same kind.
If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.
Opening it in a browser
No browser reads it.
That is the single most common reason to convert it: not that the format is bad, but that the place you want to show the file cannot read it.
What it can carry besides the content
ARW can hold EXIF, XMP and GPS coordinates.
The GPS coordinates are the field worth thinking about before sending a file anywhere: they say where the photograph was taken, and almost nothing warns you that they are still in there.
It is a working format
ARW is meant to be opened and changed. Keep the file in this format for as long as the work is going on, and export from it whenever a finished copy is needed.
What goes wrong with it
The recurring complaints: programs often show an embedded preview rather than the real data and support outside its home ground is uneven.
None of these is a reason to avoid the format. They are the things worth knowing before you are surprised by one, which is a different claim and a more useful one.
The facts, in one place
| Extension | .arw |
|---|---|
| Media type | image/x-sony-arw |
| Published by | Sony |
| First published | 2005 |