G3 to SUN Converter

Transform fax documents to SUN format online free

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Document Recovery

Extract visual content from G3 files and save as SUN — ideal for archiving important fax correspondence.

Any Device Works

Access the G3 to SUN converter from desktops, laptops, tablets, and phones — fully browser-based.

Data Protection

Your G3 files are removed immediately after processing. Converted SUN output is purged within 24 hours.

How to convert G3 to SUN

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose sun or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your sun file right afterwards

About formats

G3 is a monochrome image format based on the ITU-T Group 3 facsimile coding standard (Recommendation T.4), ratified by the CCITT in 1980 as the universal compression method for fax transmission over telephone networks. G3 files contain 1-bit (black and white) image data encoded using Modified Huffman (MH) one-dimensional coding, where each scanline is independently compressed by replacing runs of consecutive white or black pixels with variable-length codewords from a predefined Huffman table optimized for typical document content. The standard also defines an optional two-dimensional coding mode (Modified READ) that encodes each line as differences from the previous line, achieving better compression for pages with vertical redundancy. Standard G3 resolution is 204 pixels per inch horizontally and either 98 (standard) or 196 (fine) pixels per inch vertically, producing the characteristic slightly-stretched appearance of received fax documents. The encoding was carefully optimized for the real-time transmission constraints of 1980s modems operating at 2400 to 14400 bps, where encoding and decoding speed had to match the communication channel rate. One advantage is universal telecommunications compatibility: Group 3 encoding remains the mandatory baseline codec for every fax machine manufactured, ensuring that G3 image data can be transmitted to or received from any fax device worldwide. The format's efficiency for document content is another strength — the Huffman tables were statistically tuned to the run-length distributions found in business documents, and typical pages compress to under 30 KB. G3 files are supported by LibreOffice, ImageMagick, and fax server software.
Developer: ITU-T (CCITT)
Initial release: 1980
SUN is a raster image format associated with Sun Microsystems workstations, encompassing both the Sun Raster format (.ras) and the Sun Icon format used for window system icons and cursors on SunOS and Solaris systems. Sun Raster files, identifiable by their 0x59a66a95 magic number, store bitmap images in 1-bit monochrome, 8-bit indexed color, 24-bit BGR, or 32-bit XBGR modes, with optional run-length encoding compression and a 32-byte header. The Sun Icon subset is a simpler text-based format used for small monochrome bitmaps — window icons, cursor images, and toolbar graphics — stored as C-language data arrays that could be directly compiled into X Window and SunView applications. These icon files begin with a comment block specifying width, height, and optionally hot spot coordinates (for cursor images), followed by hexadecimal pixel values in a format readable by both the C compiler and the iconedit tool. Sun workstations running SunOS and later Solaris were foundational platforms for Unix computing, networking, and the early internet, and the SUN image formats were integral to their graphical environments. One advantage is the format's dual text/binary nature: Sun Icons are valid C source code that can be #included directly into applications, a practical approach to resource embedding that predates modern asset management systems. The Sun Raster variant's simplicity provides another strength — the 32-byte header and straightforward encoding make it one of the easiest binary image formats to parse. SUN format files are supported by ImageMagick, GIMP, XnView, and Unix image viewing tools.
Developer: Sun Microsystems
Initial release: 1982

Frequently Asked Questions

Why convert G3 to SUN?

Digitizing fax files to SUN format enables easy viewing, sharing, and embedding across modern platforms.

What can open SUN format?

View SUN files with IrfanView, XnView, or Sun/Solaris image tools — all handle this format natively.

Does converting G3 degrade quality?

The SUN output faithfully reproduces all content from the G3 source — quality is not compromised.

Can I use this converter at no cost?

Free for regular use. Premium plans unlock faster conversion speeds and larger batch processing limits.

Is multi-file G3 conversion supported?

Yes, batch processing works. Upload as many G3 files as needed and each becomes a separate SUN output.

Do I need to create an account?

No registration is needed for standard conversions. Upload your G3 file, convert, and download the SUN result.