HDR to RAS Converter
Processing entirely on your device — large files may take a moment.
Radiance HDR Image and Sun Raster exist for different jobs: HDR (Radiance RGBE) stores floating-point high-dynamic-range pixels — the format of lighting data and HDRI environment maps. Convert to RAS for legacy UNIX image archives.
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 to convert HDR to RAS
- 1
Select your files
Drag & drop your HDR 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 RAS". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted RAS file individually, or grab everything at once as a ZIP archive.
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
About the RAS format
The Sun Raster coder of the ImageMagick set — the unix-archive format is written natively by the magick.wasm engine, entirely in your browser.
Obscure coder formats like this are exactly what template-driven converters list and never actually convert — here it really works.
+ Strengths
- ✓Written natively by ImageMagick
- ✓Runs entirely in your browser
- ✓Free, private, no watermarks
! Limitations
- −Niche format — few modern readers
- −Feature subset varies by coder
- −Keep the original for re-editing
Why convert HDR to RAS?
Think of it as moving your file to the container that fits the job. Not display-ready — needs tone mapping RAS works differently: Written natively by ImageMagick If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this HDR to RAS 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 HDR to RAS?
No — RAS is a lossless format, so every pixel of the converted image matches your original HDR file. You can also adjust the quality/size balance before converting when the target format supports compression.
Will transparent areas survive the conversion to RAS?
Transparency is kept whenever RAS 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 HDR 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.