GIF to ORF Converter

Encoding: the GIF uses lossless LZW over a palette of at most 256 colours; 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 pixel, as indexes into a palette in the GIF; ORF allows 12 bits per channel, and the DNG written here has 8 bits per channel, linearised.

Colour: an indexed palette of up to 256 colours per frame in the GIF; ORF supports camera RGB from a Bayer mosaic, written here as 8-bit sRGB.

Transparency: the GIF stores it as one palette entry marked transparent, so each pixel is either fully shown or fully hidden; the DNG has none, so transparent areas are filled with the colour you choose.

Animation: image blocks with their own delay and disposal method, looped by the NETSCAPE2.0 extension; the DNG holds one image, so only the first frame is converted.

Metadata: the GIF can carry comment and application extension blocks, but no EXIF; ORF can carry EXIF and Olympus maker notes, which also contain the preview, but nothing is copied across.

GIF is the classic animated image format. It is limited to 256 colours per frame and 1-bit transparency, so photos look grainy and files are large, but it plays everywhere.

A GIF starts with 'GIF89a' (or the older 87a), a logical screen descriptor and an optional global colour table, then image blocks, each preceded by a graphic control extension that sets its delay and transparent colour.

GIF files usually come from reaction clips, memes, old websites and screen recordings.

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 GIF 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.