HRZ to SIXEL Converter

Turn HRZ images into SIXEL format with ease online

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Visual Fidelity

Your HRZ imagery is carefully converted to SIXEL with maximum quality retention. No unnecessary degradation during the transformation process.

No Install Needed

The converter runs entirely in your browser — no desktop software required. Works on all major platforms and devices alike.

Batch Processing

Convert multiple HRZ images to SIXEL in one session. Queue your images and let the converter process them all without manual repetition.

How to convert HRZ to SIXEL

1

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

2

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

3

Let the file convert and you can download your sixel 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
SIXEL (Six Pixel) is a bitmap graphics encoding format created by Digital Equipment Corporation (DEC) in 1983 for rendering images on character-cell printers and video terminals. The name derives from the encoding's fundamental unit: a column of six pixels represented by a single ASCII character. Each printable character in the sixel data stream (ASCII 63-126) encodes a 6-pixel vertical column, with the character's binary value determining which pixels are on or off. Color is specified through register-based palette control: a Select Color Sequence assigns an HLS or RGB color value to a numbered register, and subsequent sixel characters use that color until another register is selected. The encoding supports raster attributes for specifying pixel aspect ratio and image dimensions, repeat sequences (! followed by a count and character) for run-length compression of identical columns, and $ (carriage return) and - (new line) for navigating the sixel grid. DEC implemented SIXEL support in their VT240, VT241, VT330, and VT340 terminals, as well as multiple printer models. One advantage of the SIXEL encoding is its ASCII-clean nature: the data stream consists entirely of printable characters and standard control sequences, meaning SIXEL graphics can be transmitted through any text-based communication channel — serial terminals, SSH sessions, telnet connections — without requiring binary-safe transport or protocol modifications. The format's modern renaissance provides another remarkable dimension: after decades of obscurity, SIXEL support has been implemented in numerous contemporary terminal emulators, enabling inline image display in command-line workflows. SIXEL output can be generated by ImageMagick, libsixel, chafa, and various plotting libraries.
Initial release: 1983

Frequently Asked Questions

Why convert HRZ to SIXEL?

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

What programs open SIXEL?

Most image viewers and editors handle SIXEL — Photoshop, GIMP, IrfanView, and built-in viewers on Windows, macOS, and Linux.

Does the conversion preserve quality?

The converter retains maximum fidelity during the HRZ to SIXEL transformation. Any differences stem from the output format's own characteristics.

How long does the conversion take?

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

What is the HRZ format?

HRZ is used in amateur radio slow-scan television. It stores radio-transmitted images and ham radio communication — converting to SIXEL makes this data universally accessible.

Does this work on mobile devices?

Yes — the converter runs in any web browser, so it works on phones, tablets, laptops, and desktops regardless of operating system.