G4 to RGBO Converter

Free G4 to RGBO conversion — browser-based tool

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Private & Secure

Uploaded G4 files are erased right after conversion. RGBO results are automatically deleted within 24 hours.

Fax to Digital

Bridge the gap between legacy G4 encoding and RGBO — preserve and modernize your fax document archive.

Nothing to Install

The G4 to RGBO conversion happens in your browser — no software to download or configure on your device.

How to convert G4 to RGBO

1

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

2

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

3

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

About formats

G4 is a monochrome image format based on the ITU-T Group 4 facsimile coding standard (Recommendation T.6), ratified by the CCITT in 1984 as an improvement over Group 3 for use on error-free digital networks like ISDN rather than analog telephone lines. G4 files contain 1-bit image data compressed using exclusively two-dimensional Modified Modified READ (MMR) coding, where each scanline is encoded as a set of differences (changing elements) relative to the line above it. By eliminating the one-dimensional coding fallback and the end-of-line synchronization markers required by Group 3, G4 achieves 20-50% better compression ratios on typical document pages while producing a simpler, more regular bitstream. The format is most commonly encountered as a compression method within TIFF files (TIFF compression tag 4), where it became the standard archival format for scanned documents in enterprise document management, government records, and legal imaging systems. G4 compression is specified at 200, 300, or 400 dpi depending on the scanning application, with 300 dpi being the most common for archival-quality document imaging. One advantage is exceptional compression efficiency for document content: G4's two-dimensional prediction exploits the strong vertical correlation in text and line art pages, typically compressing a 300 dpi letter-size page to 30-50 KB — roughly half the size of equivalent Group 3 encoding. The format's entrenchment in document management infrastructure is another strength — G4 TIFF is the mandated format for many government digital records systems, court filing systems, and corporate archives, supported by every enterprise imaging platform.
Developer: ITU-T (CCITT)
Initial release: 1984
RGBO is a raw pixel data format designation used by ImageMagick, the open-source image processing suite first released in 1990, representing images as a flat sequence of Red, Green, Blue, and Opacity (inverted alpha) sample values with no header, container, or compression. The RGBO channel ordering specifies that the fourth channel is opacity rather than alpha — where alpha represents transparency (0 = transparent, max = opaque), opacity represents the inverse (0 = opaque, max = transparent). This distinction matters in compositing pipelines where the mathematical convention for the fourth channel varies between systems: some compositing models work with alpha (transparency), while older conventions including portions of ImageMagick's internal processing historically used opacity. RGBO files contain raw sample data at a user-specified bit depth (8-bit, 16-bit, or floating-point per channel), with pixels stored in scanline order. Because there is no header, the image dimensions, bit depth, and endianness must be specified externally when reading the file — typically via ImageMagick command-line arguments. One advantage is direct compatibility with processing pipelines that use the opacity convention: RGBO eliminates the need for channel inversion when interfacing with systems that expect opacity rather than alpha, preventing subtle compositing errors that occur when transparency conventions are mixed. The format's raw-data nature provides another practical benefit — with no encoding overhead, RGBO data can be memory-mapped, processed with SIMD instructions, or piped between processes with minimal latency. RGBO is primarily used within ImageMagick processing chains and can be converted to any other format using ImageMagick's extensive format support.
Initial release: 1990

Frequently Asked Questions

Why convert G4 to RGBO?

G4 files require specialized fax viewers. Converting to RGBO lets anyone open the content easily.

How do I view a RGBO file?

Use ImageMagick or SGI-compatible tools to view RGBO files.

Will my G4 content stay sharp in RGBO?

Full resolution is preserved during G4 to RGBO conversion. Text and graphics remain sharp and clear.

Is there a charge for G4 to RGBO?

Basic conversions are free. Premium subscriptions provide priority processing and expanded daily capacity.

Can I process many G4 files in one go?

Absolutely — add several G4 files at once. Each gets its own RGBO conversion and individual download link.

How fast is G4 to RGBO conversion?

Most G4 files convert to RGBO in seconds. Processing runs on cloud servers so your device stays unaffected.