JBG to PGX Converter

Transform JBG files into PGX — instant and free

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Image Liberation

Free your document images from the JBG format — PGX is supported by standard viewers and browsers.

Any Device Works

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

Data Protection

Your JBG files are removed immediately after processing. Converted PGX output is purged within 24 hours.

How to convert JBG to PGX

1

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

2

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

3

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

About formats

JBG is a file extension for images compressed using the JBIG (Joint Bi-level Image experts Group) standard, formally ITU-T Recommendation T.82, completed in 1993 as a successor to the Group 3 and Group 4 fax compression standards. JBIG compression is designed for bi-level (black and white) images but can also handle grayscale and limited-color images by encoding each bit plane separately. The algorithm uses a form of arithmetic coding guided by an adaptive context model: for each pixel, the encoder examines a template of surrounding already-coded pixels to build a probability estimate, then feeds this estimate to a QM-coder (a variant of the Q-coder arithmetic coder) that produces a highly efficient binary output. JBIG achieves 20-40% better compression than Group 4 on typical document images, with the improvement being even larger on halftoned photographs and images with gradual density transitions where Group 4's simple run-length approach is less effective. The standard supports progressive encoding, where a low-resolution version of the image is transmitted first and progressively refined — useful for fax-like applications where the receiver can begin displaying the image before the full-resolution data arrives. One advantage is superior compression of documents containing halftone images: newspapers, magazines, and marketing materials that mix text with photographic halftones compress dramatically better with JBIG than with Group 3/4. The standard's ITU-T backing ensures it is implemented in document imaging hardware and software worldwide. JBG files are supported by ImageMagick and various document imaging tools.
Initial release: 1993
PGX is a simple single-component raster image format defined as part of the JPEG 2000 standard (ISO/IEC 15444) for use in conformance testing and verification of JPEG 2000 codec implementations. Introduced around 2000 alongside the JPEG 2000 specification itself, PGX files store a single image component (one color channel or grayscale plane) with a text header followed by raw pixel data, providing an unambiguous reference representation against which encoder and decoder outputs can be compared sample by sample. The header is a single ASCII line specifying endianness (ML for big-endian, LM for little-endian), signedness (+ for unsigned, - for signed), bit depth (1 to 32 bits), width, and height. The pixel data follows as raw binary values, each occupying the minimum number of bytes needed for the specified bit depth, with one value per pixel. For multi-component images (like RGB), each component is stored in a separate PGX file. The format's deliberate simplicity — no compression, no metadata, no multi-channel support — ensures there are no ambiguities in interpretation that could mask codec bugs. One advantage is verification precision: PGX's uncompressed, exactly-specified representation allows bit-exact comparison of decoded JPEG 2000 output against reference images, essential for certifying that a codec implementation conforms to the standard. The format's role in the JPEG 2000 conformance testing framework means it is implemented by every serious JPEG 2000 codec (OpenJPEG, Kakadu, etc.) and used in the official ISO conformance test suite. PGX files can also be processed by ImageMagick and various JPEG 2000 development tools.
Initial release: 2000

Frequently Asked Questions

Why convert JBG to PGX?

Digitizing JBG archives to PGX enables easy viewing, sharing, and embedding — no special imaging tools needed.

What can open PGX format?

View PGX files with OpenJPEG tools, ImageMagick, or JPEG 2000 reference software — all handle this format natively.

Does converting JBG degrade quality?

The PGX output faithfully reproduces all content from the JBG 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 JBG conversion supported?

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

Can I use this converter on a Mac?

Yes — the converter runs in any browser on macOS, Windows, Linux, Android, and iOS. Fully cross-platform.