{"id":"image-g3fax","mimeType":"image/g3fax","name":"Group 3 Fax Image","shortName":"G3-Fax","category":"Legacy \u0026 Document","extensions":[".g3"],"description":"The Group 3 Fax format (ITU-T T.4), often represented by the MIME type image/g3fax, is a legacy 1-bit monochrome raster image format designed for telefacsimile transmission over analog telephone lines. It utilizes Modified Huffman run-length encoding to compress black-and-white documents efficiently.","seo":{"title":"image/g3fax MIME Type | Complete Developer Reference \u0026 Magic Bytes","description":"Complete reference for the image/g3fax MIME type: magic bytes, software support, HTTP headers, developer snippets, and technical specifications for Group 3 Fax images.","faqs":[{"question":"What is the image/g3fax MIME type?","answer":"Defined in RFC 1494, image/g3fax is the standard MIME type for transmitting CCITT Group 3 fax images over the internet or email, representing raw bitstream data of 1-bit monochrome document scans."},{"question":"What is the magic byte for image/g3fax?","answer":"Raw G3 fax files lack a standard file header or magic bytes. The bitstream typically begins with a unique End of Line (EOL) synchronization code consisting of eleven zeros followed by a one (000000000001)."},{"question":"How can I view an image/g3fax file?","answer":"Web browsers do not natively support image/g3fax. To view these files, they must be converted to modern formats like PNG or wrapped in a TIFF container (TIFF-FX), or opened using specialized image software like ImageMagick or Ghostscript."}]},"index":{"compression":["Lossless (CCITT Group 3)"],"browserSupport":{"score":1,"label":"None"},"commonUses":["Telefacsimile (Fax) Transmission","Internet Fax (T.37)","Document Archiving","Telephony Systems"]},"technical":{"magicBytes":{"hex":"None (Raw Bitstream)","ascii":""},"container":"Raw Bitstream","compressionAlgorithm":["CCITT Group 3 (Modified Huffman / READ)"],"colorDepth":["1-bit (Monochrome)"],"transparency":false,"animation":false,"metadata":{"exif":false,"xmp":false,"iccProfile":false},"alphaChannel":false,"progressiveLoading":false,"hdrSupport":false},"history":{"developer":"CCITT (now ITU-T) / IETF","released":"1980","specification":"RFC 1494 / ITU-T Recommendation T.4"},"browserSupport":{"chrome":false,"chromeVersion":"None","firefox":false,"firefoxVersion":"None","safari":false,"safariVersion":"None","edge":false,"edgeVersion":"None","internetExplorer":false},"softwareSupport":[{"name":"ImageMagick","logo":"image-magic.webp"},{"name":"IrfanView","logo":""},{"name":"XnView","logo":""},{"name":"GIMP","logo":"gimp.svg"},{"name":"Ghostscript","logo":""}],"conversion":{"convertTo":["tiff","png","jpeg"],"convertFrom":["tiff","png","pbm"]},"developer":{"httpHeaders":[{"header":"Content-Type","value":"image/g3fax"}],"htmlAccept":"image/g3fax, .g3","fileDetection":["Extremely difficult to detect via magic bytes due to the lack of a standardized header.","Check file extension (.g3) and attempt to decode the CCITT bitstream looking for valid EOL markers."]},"prosCons":{"pros":["Extremely efficient compression for 1-bit black-and-white text and line art","Standardized via RFC 1494 for email and internet fax transmission","Low bandwidth requirements"],"cons":["Raw format lacks metadata (such as image width and resolution), requiring out-of-band information to decode accurately","Strictly limited to 1-bit monochrome imagery","Zero native web browser support"]},"specifications":{"url":"https://datatracker.ietf.org/doc/html/rfc1494","rfc":"RFC 1494","mimeAliases":["image/fax-g3"]},"developerSnippets":{"python":"import magic\nprint(magic.from_file('document.g3', mime=True)) # Will likely return 'application/octet-stream' due to lack of header","nodejs":"const FileType = require('file-type');\nconst type = await FileType.fromFile('document.g3');\nconsole.log(type?.mime); // Standard parsers will fail to identify raw G3","go":"// Standard HTTP content type detection will fall back to application/octet-stream","php":"$mime = mime_content_type('document.g3');\necho $mime; // application/octet-stream"},"relatedFormats":["tiff","pbm"]}