GIF to HRZ Converter

Convert GIF images to HRZ slow-scan TV format online

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SSTV Ready

HRZ files are directly usable in slow-scan television software — convert your GIF image for radio transmission by amateur radio operators.

Online Processing

No SSTV software needed for the conversion. Convertio creates the HRZ file on its servers — upload and download through any browser.

Secure Files

Your GIF is deleted right after conversion. The HRZ output is removed from servers within 24 hours for your privacy.

How to convert GIF 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

GIF (Graphics Interchange Format) was introduced by CompuServe on June 15, 1987 as a platform-independent image format for transmitting color graphics over the CompuServe online service's modem-speed connections. The format uses LZW (Lempel-Ziv-Welch) lossless compression on indexed-color images with a palette of up to 256 colors selected from a 24-bit RGB color space. GIF's most distinctive capability is animation: multiple image frames can be stored sequentially within a single file, each with independent delay timing, disposal methods, and local color palettes, enabling short looping animations without any video codec or player. The format also supports binary transparency (one palette entry designated as fully transparent) and interlaced display for progressive rendering. GIF became synonymous with web culture — animated GIFs proliferated across early websites, messaging platforms, and social media, evolving into a communication medium in their own right. One advantage is universal animation support — GIF animations play natively in every web browser, email client, messaging app, and social platform without plugins, codecs, or compatibility concerns, a level of ubiquity no other animation format has achieved. The lossless compression on palette-based images provides another strength: graphics with flat colors, text, and sharp edges (logos, diagrams, UI elements) compress efficiently without the artifacts that affect JPEG. Although the LZW patents that once threatened GIF's use expired in 2004, and newer formats like WebP and AVIF offer superior compression with full-color animation, GIF's cultural entrenchment keeps it irreplaceable for casual animated content.
Developer: CompuServe
Initial release: June 15, 1987
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 GIF to HRZ?

HRZ is used for slow-scan television (SSTV) in amateur radio — converting your GIF image prepares it for transmission over radio frequencies.

What uses HRZ files?

SSTV software like MMSSTV and QSSTV, along with amateur radio operators, use HRZ images for slow-scan television broadcasts.

What resolution is HRZ?

HRZ images are typically 256x240 pixels — the standard resolution for slow-scan television transmissions in amateur radio.

Does HRZ support color?

HRZ stores RGB color data, allowing color images to be transmitted via SSTV. The palette is limited by the format resolution and SSTV standards.

Is HRZ a common format?

HRZ is specific to the amateur radio SSTV community. It is a niche format with specialized tools and a dedicated user base.