DDS to ORF Converter

Encoding: the DDS uses block compression (BC1 to BC7, also called DXT) or uncompressed RGBA; ORF uses losslessly compressed sensor data, with a preview and thumbnail, 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; ORF allows 12 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; ORF 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; ORF can carry EXIF and Olympus maker notes, which also contain the preview, 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.

ORF is the raw format of Olympus and OM System cameras, built around Four Thirds and Micro Four Thirds sensors. It stores 12-bit sensor data with a JPEG preview kept inside Olympus's maker notes.

ORF looks like TIFF but replaces the version number 42 with the letters 'RO', so a little-endian file starts 'IIRO' and generic TIFF readers reject it. Its JPEG preview is not in the main image directory but inside the camera-settings block of Olympus's maker notes.

ORF files come from Olympus E-series DSLRs, OM-D and PEN mirrorless cameras and OM System bodies.

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

What ORF offers when it comes straight from the camera: Compact files from a smaller Four Thirds sensor; High Res Shot results stored as a single file; Supported across two decades of Olympus and OM System bodies. Its drawbacks: An 'IIRO' header that generic TIFF readers reject; 12-bit depth, less than most full-frame raw files; A preview hidden inside the maker notes.