DDS to ARW Converter

Encoding: the DDS uses block compression (BC1 to BC7, also called DXT) or uncompressed RGBA; ARW uses Sony's lossy compressed raw, uncompressed (since the A7R II) or lossless compressed (since the A1), and the download is a Linear DNG: demosaiced 8-bit RGB with the colour matrices raw editors need.

Bit depth: 8 bits per channel for common texture formats in the DDS; ARW allows 12 or 14 bits per channel, and the DNG written here has 8 bits per channel, linearised.

Colour: RGB(A); normal maps and packed masks store data rather than colour in the DDS; ARW supports camera RGB from a Bayer mosaic, written here as 8-bit sRGB.

Transparency: the DDS stores it as alpha inside the compressed blocks (BC2, BC3, BC7) or a 1-bit cut-out (BC1); the DNG has none, so transparent areas are filled with the colour you choose.

Other images: the DDS can hold mipmaps, cubemap faces or texture arrays; only the main image is converted.

Metadata: the DDS can carry a 128-byte header (plus a DX10 header) describing the pixel format, nothing about the picture; ARW can carry EXIF, Sony maker notes, a thumbnail and a full-size JPEG, but nothing is copied across.

DDS is a GPU texture format used by DirectX games. It stores block-compressed textures (DXT/BC) and mipmaps that graphics cards decode directly.

A DDS file starts with 'DDS ' and a 124-byte header giving the size, mipmap count and pixel format: a FourCC such as DXT1 or DXT5, or 'DX10' followed by an extra header naming a DXGI format. The largest mipmap comes first.

DDS files usually come from DirectX games, game mods and texture tools such as NVIDIA Texture Tools and Intel's texture plugin.

ARW is the raw format of Sony Alpha, RX and Cyber-shot cameras. It stores the sensor data (compressed, uncompressed or lossless compressed, depending on the model) with a full-size JPEG preview.

ARW is TIFF-based: the first directory carries EXIF and Sony's JPEG preview and the sensor data sits in a sub-directory. In Sony's classic compressed raw each block of 16 same-colour pixels keeps an 11-bit maximum and minimum plus 7-bit steps for the rest, which can leave artefacts beside high-contrast edges.

ARW files come from Sony Alpha mirrorless and SLT cameras, RX compacts and some Cyber-shot models.

Forms and workflows that ask for ARW usually feed a raw editor, and each of those opens DNG as well, so the DNG can take the ARW's place. Keep the DDS if you only need to view or share the picture.

What ARW offers when it comes straight from the camera: A full-size JPEG preview from the camera; Lossless compressed raw on recent bodies; Wide support across Sony's long Alpha line. Its drawbacks: Sony's classic compressed mode is lossy; Uncompressed files of 60 MB and more on high-resolution bodies; Creative Looks are ignored by most third-party raw editors.