DJVU to HRZ Converter

DJVU to HRZ — slow-scan TV format, free online

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SSTV Compatible

HRZ is purpose-built for slow-scan TV — your DJVU content becomes transmittable over amateur radio frequencies.

Remote Processing

The conversion runs on cloud servers — no amateur radio software or special tools needed on your device.

Near-Instant

HRZ files are tiny — DJVU to HRZ conversion is one of the fastest operations the server handles.

How to convert DJVU 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

DjVu (pronounced "deja vu") is a document format developed at AT&T Labs by Yann LeCun, Leon Bottou, Patrick Haffner, and Paul Howard, first released in 1996. The format was specifically designed for storing scanned documents and images at very high compression ratios while maintaining visual quality suitable for on-screen reading. DjVu achieves this through a layered approach: the document image is separated into a foreground layer (text and line art at full resolution), a background layer (photographs and textures at reduced resolution), and a mask layer that determines which layer is visible at each pixel. This separation, combined with purpose-built compression algorithms for each layer type, typically produces files 5-10 times smaller than equivalent JPEG or PDF scans. One advantage is exceptional compression on scanned pages — a 300 DPI color scan that might occupy 25 MB as TIFF or 500 KB as JPEG typically compresses to 40-80 KB in DjVu while preserving legible text. The progressive rendering model is another strength: DjVu files stream efficiently over networks, displaying a readable low-resolution version almost immediately while progressively refining to full quality. The format supports multi-page documents, embedded text layers for searchability, hyperlinks, annotations, and a shared dictionary mechanism that further compresses collections of similar pages. DjVu is widely used by libraries and archives for digitized historical documents and manuscripts.
Developer: AT&T Labs
Initial release: 1996
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

What is HRZ format?

HRZ is an image format used in amateur radio slow-scan television (SSTV) for transmitting images over radio.

What software handles HRZ?

SSTV decoding software and some image viewers that support amateur radio formats can open HRZ files.

Why convert DJVU to HRZ?

HRZ is needed for slow-scan TV transmission — convert document pages for amateur radio image sharing.

Is this free?

Yes — DJVU to HRZ conversion costs nothing. Premium plans offer batch support for multiple file conversions.

What resolution does HRZ use?

HRZ uses a fixed 256x240 pixel resolution — standard for slow-scan television image transmission.

How fast is the conversion?

HRZ files are small — conversion from DJVU completes almost instantly on the cloud processing system.