PNG to HRZ Converter

Convert PNG to HRZ slow-scan television format

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Amateur Radio

Convert PNG images for SSTV transmission — share pictures over amateur radio frequencies worldwide using HRZ format.

SSTV Optimized

HRZ output is sized and formatted for slow-scan television standards — ready for direct transmission in radio applications.

No Ham Software Needed

Generate HRZ files from PNG without installing SSTV software. The conversion runs online through your web browser.

How to convert PNG 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

PNG (Portable Network Graphics) is a lossless raster image format developed by the PNG Development Group and published as a W3C Recommendation on October 1, 1996, created as a patent-free replacement for GIF after the Unisys LZW patent controversy. PNG uses a two-stage compression pipeline: a prediction filter selects the optimal per-row preprocessing (none, sub, up, average, or Paeth), then DEFLATE compression encodes the filtered data. The format supports rich color modes — 1/2/4/8/16-bit grayscale, 8/16-bit per channel true color, and indexed color with palettes up to 256 entries — all with optional alpha transparency ranging from a single transparent color to a full per-pixel alpha channel with 256 or 65536 levels. PNG also stores gamma correction, ICC color profiles, text metadata, and suggested background color. One advantage is lossless compression with transparency — PNG preserves every pixel exactly while supporting smooth semi-transparent edges, making it the standard format for web graphics, UI elements, logos, screenshots, and any image where artifacts or color shifts are unacceptable. Universal support is another core strength: every web browser, operating system, image editor, and programming library handles PNG natively. The format has proven remarkably durable — after nearly three decades, PNG remains the default lossless web image format. While newer formats like WebP and AVIF offer better compression, PNG's combination of lossless quality, full transparency, and absolute ubiquity keeps it indispensable.
Initial release: October 1, 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

Why convert PNG to HRZ?

HRZ is used for slow-scan television (SSTV) in amateur radio. Convert your PNG to transmit images over radio frequencies.

What is SSTV?

Slow-scan television transmits images over radio waves one line at a time. Amateur radio operators use SSTV to share pictures worldwide.

What software uses HRZ?

MMSSTV, QSSTV, MultiScan, and various amateur radio SSTV programs handle HRZ format for image transmission.

Is PNG to HRZ free?

Yes — standard conversion is free on Convertio. Premium plans add batch processing for preparing image sets.

What resolution does HRZ use?

HRZ images are typically 256x240 pixels — matching standard SSTV transmission modes used in amateur radio.

Is HRZ color or monochrome?

HRZ stores RGB color data at its fixed resolution, supporting full-color SSTV transmission modes.

PNG to HRZ Quality Rating

3.8 (6 votes)
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