PNG to G4 Converter

Convert PNG to Group 4 fax compression free

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Superior Compression

G4 achieves better compression than G3 for monochrome documents — store more scanned pages in less space.

Document Standard

Group 4 is the enterprise standard for document imaging — your PNG scans meet archival and compliance requirements.

Private Processing

All uploaded PNG files are removed after conversion. G4 outputs are automatically deleted within 24 hours.

How to convert PNG 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

PNG (Portable Network Graphics) is a lossless raster image format developed by the PNG Development Group and published as a W3C Recommendation on October 1, 1996, created as a patent-free replacement for GIF after the Unisys LZW patent controversy. PNG uses a two-stage compression pipeline: a prediction filter selects the optimal per-row preprocessing (none, sub, up, average, or Paeth), then DEFLATE compression encodes the filtered data. The format supports rich color modes — 1/2/4/8/16-bit grayscale, 8/16-bit per channel true color, and indexed color with palettes up to 256 entries — all with optional alpha transparency ranging from a single transparent color to a full per-pixel alpha channel with 256 or 65536 levels. PNG also stores gamma correction, ICC color profiles, text metadata, and suggested background color. One advantage is lossless compression with transparency — PNG preserves every pixel exactly while supporting smooth semi-transparent edges, making it the standard format for web graphics, UI elements, logos, screenshots, and any image where artifacts or color shifts are unacceptable. Universal support is another core strength: every web browser, operating system, image editor, and programming library handles PNG natively. The format has proven remarkably durable — after nearly three decades, PNG remains the default lossless web image format. While newer formats like WebP and AVIF offer better compression, PNG's combination of lossless quality, full transparency, and absolute ubiquity keeps it indispensable.
Initial release: October 1, 1996
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 PNG to G4?

G4 offers superior compression for monochrome documents compared to G3. It is the standard for archival document imaging and TIFF-F format.

What uses G4 compression?

Document management systems, TIFF-F archives, high-speed fax, and enterprise scanning solutions use Group 4 compression extensively.

Is G4 better than G3?

Yes — G4 achieves smaller files than G3 for the same content. It uses two-dimensional encoding for more efficient monochrome compression.

Is PNG to G4 free?

Basic conversions are free on Convertio. Premium plans support batch conversion for large document scanning workflows.

Is G4 monochrome only?

Yes — Group 4 compression handles monochrome (bi-level) images. Your PNG is converted to black and white during processing.

Is G4 lossless?

Yes — G4 is a lossless compression algorithm. Every pixel of the monochrome image is preserved exactly in the output.

PNG to G4 Quality Rating

4.4 (28 votes)
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