MOBI to HRZ Converter

Convert MOBI pages to HRZ format — free online tool

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SSTV Compatibility

Render MOBI ebook pages as HRZ images — the format designed for Slow Scan Television, enabling image transmission over amateur radio.

Niche Format Access

Finding tools to create HRZ images can be challenging. Convertio makes it simple — just upload your MOBI and select HRZ output.

Private and Secure

Uploaded MOBI ebooks are removed right after processing. HRZ output files are deleted from servers within 24 hours automatically.

How to convert MOBI 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

MOBI is an ebook format originally developed by Mobipocket SA, a French company founded in 2000 that was later acquired by Amazon in 2005. The format builds on the PalmDOC/PDB container structure, adding support for HTML-based content markup, embedded images, a DRM layer, and a JavaScript subset for limited interactivity. MOBI files use a record-based database architecture inherited from Palm OS, with a header structure containing metadata like title, author, publisher, and language followed by compressed HTML content records. The format became the foundation of Amazon's early Kindle ecosystem — the original AZW format used on first-generation Kindles was essentially MOBI with Amazon's own DRM wrapper. MOBI supports reflowable text with basic formatting including bold, italic, headings, lists, and tables, as well as internal hyperlinks and a built-in table of contents. One advantage is broad device compatibility: MOBI files are recognized by Kindle devices and apps spanning over a decade of hardware, as well as numerous third-party readers on desktop and mobile platforms. The format's lightweight structure is another strength — even long novels produce compact files that load quickly on modest hardware. While Amazon has since moved to the more capable AZW3/KF8 format for new publishing, MOBI remains widely circulated in existing ebook libraries and continues to be produced by conversion tools like Calibre for maximum Kindle compatibility.
Developer: Mobipocket SA
Initial release: 2000
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 MOBI to HRZ?

HRZ is used in Slow Scan Television (SSTV) — amateur radio operators use it to transmit images over radio frequencies. Convert ebook pages for SSTV sharing.

How do I open an HRZ file?

SSTV software like MMSSTV and QSSTV handle HRZ files. GIMP with appropriate plugins and ImageMagick can also process HRZ images.

What resolution does HRZ use?

HRZ images are fixed at 256x240 pixels — the standard resolution for Slow Scan Television transmission over ham radio frequencies.

Is HRZ a common format?

HRZ is niche — used almost exclusively in the amateur radio and SSTV community. For general image needs, PNG or JPG are more practical.

Can I batch-convert MOBI pages to HRZ?

Yes. Upload your MOBI ebook and Convertio will process all pages into HRZ format automatically in one session.