HRZ to CGM Converter

Convert radio-transmitted HRZ images to CGM format online

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Universal Access

Convert niche HRZ data into standard CGM that opens on any device. Bridge the gap between specialized and mainstream formats effortlessly.

Any Device Works

Run the HRZ to CGM converter from any device — desktop, laptop, tablet, or phone. All you need is a web browser to get started.

Secure Processing

Your HRZ uploads are deleted right after conversion, and the resulting CGM output is removed from servers within 24 hours for full privacy.

How to convert HRZ to CGM

1

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

2

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

3

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

About formats

HRZ is a simple raster image format associated with slow-scan television (SSTV), a method of transmitting still images over radio frequencies used by amateur radio operators since the late 1950s when Copthorne Macdonald pioneered the technology. HRZ files store images at a fixed resolution of 256x240 pixels in raw RGB format, with each pixel represented as three bytes (red, green, blue) at 8 bits per channel, producing uncompressed files of exactly 184,320 bytes. The format has no header, no metadata, and no compression — the file is simply a sequential dump of raw pixel data in row-major order. This extreme simplicity reflects the format's origins in the amateur radio community, where SSTV images are transmitted as audio tones encoding luminance and chrominance values over narrow-bandwidth HF (shortwave) radio channels. The fixed 256x240 resolution corresponds to common SSTV transmission modes, and HRZ files serve as the digital capture or storage medium for received SSTV transmissions. One advantage is the format's zero-overhead structure: with no parsing, decompression, or metadata processing required, HRZ files can be read by any program capable of reading raw pixel data with known dimensions — a single function call in virtually any programming language. The format's connection to amateur radio SSTV culture is another notable aspect: HRZ files document a unique form of image communication where operators transmit photographs over thousands of miles using nothing but radio waves and audio encoding, a practice that continues today alongside digital modes. HRZ files can be opened by ImageMagick, GIMP, and specialized SSTV software.
Developer: SSTV Community
Initial release: 1985
CGM (Computer Graphics Metafile) is a vector graphics standard defined by ISO 8632, first published in 1987 and developed through the ISO/IEC JTC 1/SC 24 committee. The standard defines a device-independent format for storing and transferring two-dimensional vector graphics, raster images, and text. CGM supports three encoding methods: character encoding (compact text representation), binary encoding (efficient machine-readable form), and clear-text encoding (human-readable for debugging). The format describes graphical primitives including polylines, polygons, ellipses, circular arcs, splines, and text with associated attributes for color, line style, fill patterns, and clipping boundaries. CGM found its strongest adoption in technical documentation, particularly in aerospace, defense, and industrial sectors where long-term archival and precise technical illustration are critical. One advantage is formal standardization — as an ISO standard, CGM provides vendor-neutral, specification-driven interoperability guaranteed across compliant implementations. The format's adoption in specialized industries is another practical strength: WebCGM, a W3C profile of CGM, became the mandated illustration format for interactive electronic technical manuals in the aerospace industry (ATA iSpec 2200), ensuring CGM's continued relevance in aviation maintenance documentation. While general-purpose vector work has moved to SVG and PDF, CGM persists in regulated industries where certified, standards-based graphics interchange is mandatory.
Initial release: 1987

Frequently Asked Questions

Why convert HRZ to CGM?

HRZ requires niche software to open. Converting to CGM lets you share and view your SSTV images on virtually any platform.

What programs open CGM?

Adobe Illustrator, Inkscape, and CorelDRAW are the main editors for CGM. Preview and other viewers can display it too.

Can I convert on a phone or tablet?

Absolutely — the online converter works in mobile browsers just as well as on desktop. No app installation is required at all.

Will my image lose quality?

Quality depends on the target format. CGM vector output preserves data within its format constraints — no unnecessary degradation occurs.

How long does the conversion take?

Most HRZ to CGM conversions finish within seconds. Larger or more complex images may take slightly longer depending on the data size.

Can I batch convert HRZ to CGM?

Yes — Convertio supports batch uploads. Add multiple HRZ images and convert them all to CGM at once to speed up your workflow.