HEIC to G4 Converter

Convert HEIC to G4 free — high-efficiency fax format

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Superior Fax Compression

G4 achieves better compression than G3, producing smaller monochrome files — optimal for digital fax archives and document storage.

Cloud-Powered

No fax encoding software needed — Convertio converts your HEIC to G4 entirely on remote servers through your browser.

Secure Handling

Uploaded HEIC photos are deleted after processing. G4 output files are purged automatically within 24 hours.

How to convert HEIC to G4

1

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

2

Choose g4 or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your g4 file right afterwards

About formats

HEIC (High Efficiency Image Container) is Apple's branded implementation of the HEIF (High Efficiency Image File Format) standard that uses HEVC (H.265) as its image compression codec. Apple adopted HEIC as the default photo format on iPhones and iPads starting with iOS 11 in September 2017, replacing JPEG for newly captured images. HEIC files store photographs compressed with the intra-frame coding mode of the HEVC video codec, which applies sophisticated prediction, transform, and entropy coding techniques that achieve roughly 50% better compression than JPEG at equivalent visual quality. The ISOBMFF (ISO Base Media File Format) container supports multiple images in a single file, enabling Live Photos (a still plus a short video clip), burst sequences, depth maps from dual-camera systems, and HDR gain maps that allow compatible displays to render extended dynamic range. HEIC also stores alpha channels, auxiliary images for computational photography features (portrait mode depth data, semantic segmentation masks), and comprehensive EXIF/XMP metadata. One advantage is storage efficiency: iPhones shooting HEIC use roughly half the storage of equivalent JPEG captures with no visible quality loss, a significant benefit on devices where storage is finite and photos accumulate rapidly. The format's integration with Apple's ecosystem is another key strength — HEIC files are natively supported across macOS, iOS, iPadOS, and iCloud Photos, and automatic JPEG transcoding during file sharing ensures compatibility when sending photos to non-Apple devices. HEIC can also be opened by Windows 10/11 (with codec), GIMP, ImageMagick, and Adobe Lightroom.
Developer: MPEG / Apple
Initial release: 2015
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

Frequently Asked Questions

Why convert HEIC to G4?

G4 provides better compression than G3 fax — ideal when you need compact monochrome images for document imaging and digital fax archives.

What software reads G4?

Document imaging systems, fax servers, TIFF viewers with G4 support, and ImageMagick all handle Group 4 encoded images.

How is G4 different from G3?

G4 uses two-dimensional encoding for higher compression ratios. It produces smaller files than G3 while maintaining the same image quality.

Will the output be color?

G4 is a monochrome format — your HEIC color photo is converted to black and white with high-contrast rendering.

Is HEIC to G4 conversion free?

Yes, basic conversions are free on Convertio. Premium plans offer batch processing and faster conversion speeds.

HEIC to G4 Quality Rating

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