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File Format Guide
What is an ARW file?
ARW is Sony's RAW format, inherited from Minolta when Sony acquired its camera division and used across the Alpha line ever since. Its one notable quirk is a compression setting that was, for years, not optional.
ARW at a glance
What are ARW and SR2 files?
Proprietary RAW image formats used by Sony Alpha and Cyber-shot cameras. SR2 is an older format, while ARW is the current standard.
How to open them?
Adobe Lightroom, Photoshop, Apple Photos, or Sony's Imaging Edge software.
Typical use:
Professional photography using Sony camera systems.
Origin:
Developed by Sony.
Modern alternatives:
Archiving as DNG.
ARW specifications
Full name
Sony Alpha RAW
File extensions
.arw; .sr2 and .srf on older Sony and Minolta bodies
Container
TIFF/EP-based
Compression
Compressed (lossy), lossless compressed, or uncompressed, depending on model
Colour depth
12 or 14 bits per channel
Embedded previews
Full-size JPEG plus thumbnails
Cameras
Sony Alpha DSLR, SLT and E-mount mirrorless
Introduced
2006, with the Alpha line
Browser support
None
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The compressed RAW question
For much of the Alpha line's history, Sony's compressed ARW was the only option, and it is lossy: it applies a tone curve to the sensor data and delta-encodes pixels in groups of sixteen. The result is roughly half the size of uncompressed, and in almost all real shooting it is indistinguishable.
The exception is high-contrast edges — a bright light source against a dark background, sun through branches — where the group encoding can produce faint posterised artefacts. Astrophotographers and landscape photographers doing heavy recovery noticed, and after sustained complaint Sony added uncompressed RAW to the A7R II and later lossless compressed to newer bodies, which is now the sensible default where offered.
SR2, SRF, and the Minolta inheritance
Sony's camera division came from its acquisition of Konica Minolta, and the earliest Sony RAW files reflect that: SRF on the DSC-R1, SR2 on the early Alpha DSLRs, then ARW from around 2006 onward. All three are TIFF/EP-based and structurally related.
Modern software generally handles all of them, but the older two are the ones most likely to be missing from a given program's support list, simply because so few files exist.
Frequent format revisions
Sony iterates camera models quickly and adjusts the ARW structure as it goes — new metadata, new compression variants, changes to how sensor data is packed. The extension stays the same while the contents shift underneath it.
The practical consequence is that a brand-new Sony body often cannot be read by editors until they ship an update, even though the files are nominally the same format you have been using for years. Checking your software's supported-camera list before a shoot with a new body is worth the minute it takes.
Convert ARW files in your browser
Zolvo's image converter runs entirely on your own machine — your files are never uploaded to a
server. Drop a ARW file in and pick an output format, or jump straight to a common one:
Yes. The standard compressed ARW applies a tone curve and encodes pixels in groups of sixteen, discarding some data. It is invisible in normal use but can produce faint artefacts at extreme high-contrast edges. Newer bodies offer lossless compressed or uncompressed alternatives.
Why won't my editor open ARW files from my new camera?
Sony revises the ARW structure with new models, so editors must add support model by model. A firmware or catalogue update usually resolves it; converting to DNG is the standard workaround in the meantime.
What is the difference between ARW, SR2 and SRF?
They are successive generations of Sony's RAW format. SRF and SR2 come from the earliest Sony and Minolta-derived cameras; ARW has been standard since around 2006. All are TIFF/EP-based, but the older two are less widely supported.
Which ARW compression should I choose?
Lossless compressed if your camera offers it — full quality at a substantially smaller size. Uncompressed only if lossless compressed is unavailable and you are doing work that pushes the file hard.
