Description of Sony RAW file formats (SRF, SR2, ARW and ARQ)

Version 0.53 (21nov2024)

(this is work in progress)

Introduction

This document describes RAW file formats used by Sony cameras, with extensions SRF, SR2, ARW and ARQ, from 2004 to today.

All formats are based on TIFF format, with Intel (little) endianess ('II' marker). SRF appeared in January 2004 (DSC-F828), SR2 in December 2005 (DSC-R1) and ARW in July 2006 with Alpha DSLR-A100.

ARQ, pixel shifting, appeared in November 2017 (A7R III).

Evolution of Sony RAW formats

SRF likely stands for Sony Raw File, SR2 is version 2 of SRF, and ARW means Alpha RAW.

RAW versions and formats had additional features over time:

SRF, SR2 and ARW 1.0 : 12 bits uncompressed
ARW 2.1 : 12 bits cRAW (11 bits + 7 bits). Lossy. 2008
ARW 2.3 : 14 bits. (2012)
ARW 4.0 : lossless compression (2021). A1 also introduces YUV420 burst format, which is lossy.

Here is a more detailed view of evolution, and links to implementations:

Model	Release date	RAW format	dcraw / libraw support
DSC-F828	jan2004	SRF. First CyberShot with RAW	parseSonySRF()
DSC-V3	dec2004	SRF	sony_load_raw()
DSC-R1	dec2005	SRF2	1.283, 7sep2005 parseSonySR2()
A100	jul2006	ARW 1.0, 12bits	1.331, 21jun2006 sony_arw_load_raw()
A700	dec2007	ARW 2.0	1.393, 8.78, 30oct2007, arw2 sony_arw2_load_raw()
A900	oct2008	RAW, cRAW. ARW 2.1	1.405, 8.88, 15sep2008
NEX-3/NEX-5	jun2010	ARW 2.2	1.434, 9.01, 30may2010
RX100	jun2012	ARW 2.3, 12 bits	1.451, 9.16, 5jul2012
SLT-A99	dec2012	ARW 2.3, 14 bits first 14bits sensor	1.453, 9.17, 23dec2012
RX1	feb2013	ARW 2.3, 14 bits	1.453, 9.17, 23dec2012
a7	jan2014	ARW 2.3, 12 bits only?
a7R	fev2014	ARW 2.3.1
a7R II	jun2015	ARW 2.3.1, 14 bits uncompressed 14bits	uncompressed: unpacked_load_raw()
RX10 III	jul2016	ARW 2.3.2
a9	apr2017	ARW 2.3.3
a7R III	nov2017	ARW 2.3.3 can create ARQ	sony_arq_load_raw
a7 III	fev2018	ARW 2.3.3
a9 II	aug2020	ARW 2.3.5
a1	apr2021	ARW 4.0. First ILC with Lossless RAW	30fps RAW seems YUV420 : https://github.com/dnglab/dnglab/pull/269/commits (jan2023)
a7 IV	fev2022	ARW 4.0
a7R V	jan2023	ARW 4.0
a6700	jul2023	ARW 4.0.1
a9 III	nov2023	ARW 5.0
a1 II	nov2024	ARW 5.0.1	exiftool RAW File Type is Lossless Compressed RAW

You can extract format information with Exiftool with -FileFormat :

> exiftool -FileFormat -SonyModelID -RAWFileType RAW_SONY_A100.ARW
File Format : ARW 1.0
Sony Model ID : DSLR-A100

> exiftool -FileFormat -SonyModelID -RAWFileType A1_DSC02244.ARW
File Format : ARW 4.0
Sony Model ID : ILCE-1
RAW File Type : Uncompressed RAW

> exiftool -FileFormat -SonyModelID -RAWFileType DSC00987_a1_ii.ARW
File Format                     : ARW 5.0.1
Sony Model ID                   : Unknown (400)
RAW File Type                   : Lossless Compressed RAW

Compression

Based on dcraw and dnglab code source, there are 4 different kind of compression:

SRF : 16bits aligned, 12 bits data, big endian. Some data must be decrypted first. See sony_load_raw() in libraw
ARW1 : 12 bits (starting with A100). See sony_arw_load_raw()
ARW2 (first with A700, A850 and A900)
- either uncompressed 12bits. Uncompressed 14 bits since A7R II
- or cRAW for "compressed Raw". This is lossy : "11 bit 'base' values, 7-bit 'deltas', 11 to 14 bit tone curve" say Rawdigger
LossLess Jpeg92 (starting with Alpha 1), in 2021

"Compressed" is used by Sony, where this is "lossy".

"Uncompressed" is used when it is "lossless".

But there is lossless compression ! They waited 2021 to adopt lossless jpeg when Canon use it since 2004 !

TIFF Structure

Below are examples of TIFF structure for SRF, SR2 and some ARW versions.

SRF (jan 2004)

IFD0 (18 entries)
- ImageWidth = 3360
- ImageHeight = 2460
- EXIF Subdir (20 entries)
- SRF MakerNote Subdir
  - SRF0 (1 entry)
  - SRF1 (encrypted, 2 entries)
  - SRF2 (encrypted, 130 entries)
  - SRF3 (130 entries)
  - SRF4 (130 entries)
  - SRF5 (130 entries)
  - SRF6 (9 entries)
IFD1 (6 entries)

from http://rawsamples.ch/raws/sony/RAW_SONY_DSC-F828.SRF (Exiftool output: RAW_SONY_DSC-F828.SRF.txt)

SR2 (dec 2005)

IFD0 (15 entries)
- SubfileType = 1
- SubIFD (19 entries)
  - SubfileType = 0
  - ImageWidth = 3984
  - ImageHeight = 2608
  - BitsPerSample = 14
- EXIF Subdir (30 entries)
  - MakerNote Subdir
- SR2Private Subdir ( 6 entries)
  - SR2SubIFD (encrypted, 101 entries)
    - SR2SubIFD (132 entries)
    - SR2DataIFD1 (132 entries)
    - SR2DataIFD2 (132 entries)
IFD1 (11 entries)

See http://www.rawsamples.ch/raws/sony/r1/RAW_SONY_R1.SR2 (Exiftool : RAW_SONY_R1.txt)

ARW

version 1.0

IFD0 (19 entries)
- EXIFIFD (36 entries)
  - MakerNoteSony (28 entries)
    - MakerNoteMinolta
- SR2Private
  - MRW PRD segment
  - MRW WBG segment
  - MRW RIF segment
IFD1 (11 entries)

See http://www.rawsamples.ch/raws/sony/a100/RAW_SONY_A100.ARW (Exiftool: RAW_SONY_A100.txt)

version 4.0

Dated July 2021

IFD0 (18 entries)
- SubfileType = 1
- SubIFD (35 entries)
  - SubfileType = 0
  - ImageWidth = 6048
  - ImageHeight = 4024
  - BitsPerSample = 14
- XMP directory
- ExifIFD directory (41 entries)
  - MakerNoteSony5 (99 entries)
    - Deciphered Tag9400c directory
    - Deciphered Tag9401 directory
- PrintIM (SubDirectory)
- SR2Private (9 entries)
  - SR2SubIFD (209 entries)
    - SR2DataIFD SubDirectory (124 entries)
    - SR2DataIFD1 directory with 124 entries
    - SR2DataIFD2 directory with 124 entries
    - SR2DataIFD3 directory with 124 entries
    - SR2DataIFD4 directory with 124 entries
    - SR2DataIFD5 directory with 124 entries
    - SR2DataIFD6 directory with 124 entries
    - SR2DataIFD7 directory with 124 entries
    - SR2DataIFD8 directory with 124 entries
    - SR2DataIFD9 directory with 124 entries
    - SR2DataIFD10 directory with 124 entries
    - SR2DataIFD11 directory with 124 entries
    - SR2DataIFD12 directory with 124 entries
IFD1 directory with 14 entries
- SubfileType = 1

Exiftool : SONY_A9_DSC04458.txt

ARQ

ARQ likely means Alpha Raw Quad shots, which uses pixel shifting to capture high resolution pictures by combining 4 ARW pictures. This features is available with A7R III and requires Sony software Image Edge. See also Pixel Shift Multi Shooting | SONY.

Supported by RawDigger 1.2.24 and Lightroom Classic CC 7.3.

>exiftool -FileFormat -RAWFileType -BitsPerSample -PixelShiftInfo "Sony-ILCE-7RM3.tif"
File Format                     : ARW 2.3.5
RAW File Type                   : Uncompressed RAW
Bits Per Sample                 : 14
Pixel Shift Info                : Group 12094102, Composed 4-shot (0x3c3)