QOI to HDR Converter
Processing entirely on your device — large files may take a moment.
QOI (Quite OK Image) is a 2022 lossless format with a ~200-line spec — PNG-class simplicity that compresses similarly fast. Converting HDR to PNG produces a tone-mapped preview usable in any image viewer.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How QOI compares to HDR
| QOI | HDR | |
|---|---|---|
| Compression | Lossless (RLE/delta) | RGBE (RLE runs) |
| Transparency | Supported | Not supported |
| Animation | Not supported | Not supported |
| Metadata | None | Radiance comments |
| Best for | Hobby engines, lossless simplicity | Lighting data, environment maps |
How to convert QOI to HDR
- 1
Select your files
Drag & drop your QOI files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to HDR". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted HDR file individually, or grab everything at once as a ZIP archive.
About the QOI format
QOI (Quite OK Image, 2021) is a lossless format defined in one short specification document: a stream of simple run-length and delta ops over linear pixels. An encoder fits in 300 lines, decodes faster than PNG, and compresses comparably for photographic content.
It has found a home in emulators, demoscene projects and hobby engines — anywhere people want images without a codec dependency. Viewers rarely support it, so converting QOI to PNG is the way to bring these files into normal tools.
+Strengths
- ✓Radically simple spec (~200 lines)
- ✓Lossless with fast decode
- ✓No patent or licensing questions
!Limitations
- −Almost no viewer support
- −Larger than modern codecs for many images
About the HDR format
HDR (Radiance RGBE) is the veteran high-dynamic-range format of lighting research and 3D rendering: pixels stored as a shared 8-bit exponent plus per-channel mantissas, letting one file hold both a sun and a shadow with no clipping. HDRI environment maps for 3D scenes are almost always HDR files.
Standard image viewers show it badly or not at all, because the values can exceed what a screen can display. Converting HDR to PNG tone-maps the file into an 8-bit preview — good for quick inspection, though the floating-point original remains the render-grade master.
+Strengths
- ✓True high-dynamic-range values
- ✓The standard of HDRI environment maps
- ✓Compact for its precision
!Limitations
- −Not display-ready — needs tone mapping
- −Viewer support is scarce
Why convert QOI to HDR?
Converting makes sense where the strengths of HDR meet what QOI cannot give you. True high-dynamic-range values Meanwhile Almost no viewer support One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this QOI to HDR converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Will I lose quality converting QOI to HDR?
No — HDR is a lossless format, so every pixel of the converted image matches your original QOI file. You can also adjust the quality/size balance before converting when the target format supports compression.
Will transparent areas survive the conversion to HDR?
Transparency is kept whenever HDR actually supports an alpha channel. If the target format has none (like JPG), transparent areas are flattened onto a white background — that is a property of the format, not of this tool.
Can I convert several QOI files at once?
Yes — drop as many files as you like into the tool and they are converted in one batch. When more than one file comes out, everything is bundled into a ZIP for a single download.