WOFF to HRZ Converter

Render web font glyphs into HRZ slow-scan TV image format

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Radio-Ready Images

Render WOFF font glyphs into HRZ format — create callsign graphics and text overlays for slow-scan television transmission.

No SSTV Software Needed

Convertio handles font rendering to HRZ in your browser. Install SSTV tools only when you need to transmit the resulting image.

Simple Output

HRZ is a fixed-resolution, straightforward format — conversion produces lightweight files ready for amateur radio workflows.

How to convert WOFF to HRZ

1

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

2

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

3

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

About formats

WOFF (Web Open Font Format) is a web font container format developed by Jonathan Kew, Tal Leming, and Erik van Blokland, and standardized by the W3C as a Recommendation in December 2012. The format wraps existing TrueType or OpenType font data in a compressed container with additional metadata, specifically designed for efficient delivery over HTTP as part of web pages using the CSS @font-face rule. WOFF applies table-level zlib compression to the font data, typically achieving 40-50% size reduction compared to raw TTF or OTF files, while preserving every table and glyph exactly. An extended metadata block allows foundries to embed licensing information, credits, and descriptions that travel with the font file. WOFF was created to address a practical impasse: type foundries were reluctant to allow their fonts on the web in raw TTF/OTF form (easily installable as desktop fonts), while the web standards community needed a freely implementable font delivery mechanism. One advantage is universal browser support — every modern browser across desktop and mobile platforms renders WOFF natively, making it the baseline format for web typography. The distinct file signature and container structure also provides a licensing benefit, giving foundries a format distinguishable from desktop fonts while remaining technically straightforward. WOFF 2.0, standardized in March 2018, replaces zlib with Brotli compression for an additional 20-30% size reduction and has achieved similarly broad browser adoption. Together, WOFF and WOFF2 enabled the custom web typography revolution that transformed web design from a handful of system fonts to millions of typeface options.
Developer: W3C
Initial release: December 13, 2012
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

Frequently Asked Questions

Why convert WOFF to HRZ?

HRZ is used in slow-scan TV (SSTV) for ham radio. Converting WOFF to HRZ lets you create text overlays and callsign graphics for transmission.

How do I open an HRZ file?

SSTV software like MMSSTV and QSSTV reads HRZ files. ImageMagick can also process HRZ images for viewing and further format conversion.

What is the HRZ image format?

HRZ is a simple 256x240 pixel format used in amateur radio SSTV transmission. It stores raw color data at a fixed resolution for radio signals.

What resolution does HRZ use?

HRZ images are fixed at 256x240 pixels — matching the standard resolution for slow-scan television transmission in amateur radio operations.

Is this conversion free?

Yes, Convertio provides WOFF to HRZ conversion free online — no SSTV hardware or ham radio software needed for the conversion.