Convert HRZ Image Free

How to Convert Files

Convert HRZ slow-scan television images to and from standard formats in your browser. Everything runs locally on your device.

What an HRZ file holds

HRZ is a Slow Scan Television image format, associated with the amateur-radio practice of sending still pictures over voice-bandwidth radio links. It stores a small, fixed-size image suited to the low resolution that slow-scan transmission can carry.

Slow-scan television trades speed for bandwidth: a single frame takes seconds to minutes to send, encoded as audio tones, which is how a picture can travel over an ordinary radio channel. The HRZ format captures such a frame as raw RGB data at the modest dimensions these transmissions use.

Strengths and limits

HRZ matches its niche well: a small, simple raw image is all that slow-scan television needs, and keeping it plain makes it easy for radio and imaging software to handle.

Outside amateur radio it has almost no presence. The fixed low resolution and uncompressed data make it unsuitable for general imaging, and support is limited to ImageMagick and specialist tools. Captured frames are converted to PNG for storage.

HRZ Format Evolution

The HRZ format was developed in the 1980s as part of the Slow Scan Television (SSTV) movement within amateur radio. It was created to address the need for transmitting still images over limited bandwidth voice channels. The format allowed operators to send images with minimal data, making it feasible to share visual content in a medium where bandwidth was constrained.

As SSTV gained popularity, HRZ became a standard format among radio enthusiasts. Various software tools emerged to facilitate encoding and decoding HRZ images, leading to widespread adoption. Over time, HRZ has remained largely unchanged, preserving its simplicity and effectiveness for low-resolution image transmission in amateur radio communities worldwide.

Using HRZ Effectively

Choose HRZ when working in environments where bandwidth is limited, such as during SSTV transmissions. HRZ is suitable for applications that require low-resolution images without the need for compression. Common workflows include capturing images from a camera, converting them to HRZ format, and transmitting them via radio. This is ideal for visual communication in remote areas or during emergency situations.

Be aware that HRZ files may not be compatible with standard image viewers. Use specialized SSTV software for conversion and viewing. When converting to or from HRZ, ensure the image is appropriately sized to fit the format's specifications. Maintain the original aspect ratio to avoid distortion. Users should also verify that their radio equipment is configured for SSTV to ensure successful transmission and reception.

Working with HRZ files

You will encounter HRZ files in the context of amateur-radio slow-scan television, either as received frames or as images prepared for transmission.

To view or share a slow-scan frame, convert it to PNG, which is universally readable and compresses the small image losslessly. The plain RGB data converts directly without colour conversion.