HDR to HRZ Converter

Seamless HDR to HRZ conversion online — try now

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Nothing to Install

The entire HDR to HRZ conversion happens in your web browser. No downloads, no plugins — just a clean online tool.

Bulk Conversion

Upload multiple HDR files and convert them all to HRZ in one session. Each processes independently — download all results at once.

Secure Processing

Your HDR file is deleted right after conversion. The HRZ output is purged from servers within 24 hours — your data stays private.

How to convert HDR 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

HDR (also known as RGBE or Radiance HDR) is a high-dynamic-range image format created by Greg Ward Larson as part of the Radiance) lighting simulation system, developed at Lawrence Berkeley National Laboratory starting in 1985 with the HDR format emerging around 1989. The format stores floating-point RGB pixel values using a compact 32-bit-per-pixel encoding called RGBE (Red, Green, Blue, Exponent): three 8-bit mantissa bytes share a single 8-bit exponent, representing luminance values across a range of roughly 76 orders of magnitude while keeping file sizes comparable to standard 24-bit images. HDR files begin with a text header containing rendering and exposure metadata, followed by the RGBE pixel data compressed with a scanline-oriented run-length encoding scheme. The format captures the full luminance range of real-world scenes — from deep shadows to direct sunlight — enabling physically accurate lighting calculations, tone mapping to different display conditions, and post-capture exposure adjustment without the clipping artifacts inherent in 8-bit formats. One advantage is the format's foundational role in HDR imaging: Radiance HDR pioneered the concept of storing real-world luminance values in image files, and the .hdr format became the standard for light probe images and environment maps used in image-based lighting across the 3D rendering industry. The format's compact encoding is another practical strength — the RGBE scheme provides far more dynamic range than 8-bit formats while using only 33% more storage per pixel, a favorable tradeoff that made HDR practical on storage-limited systems of the late 1980s. HDR files are supported by Photoshop, GIMP, ImageMagick, Blender, and all major 3D renderers.
Developer: Greg Ward Larson
Initial release: 1989
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 HDR to HRZ?

Sharing HDR lighting data with clients requires a standard format — HRZ conversion handles the tonemapping automatically.

What programs open HRZ files?

ImageMagick and slow-scan television (SSTV) software open HRZ radio image format files

Will the converted HRZ keep the original resolution?

Yes — the default conversion preserves the original pixel dimensions

Does HDR to HRZ conversion preserve quality?

The converter optimizes for best visual fidelity. HRZ may apply compression

How fast is HDR to HRZ conversion?

Most conversions complete within seconds. Larger or more complex files may take slightly longer, but processing happens on fast cloud servers.

Does this converter work on mobile devices?

Absolutely. The browser-based converter runs on phones and tablets — iOS, Android, or any device with a modern browser handles it fine.