Free Online Radiance HDR Viewer (No Signup)
Also opens DWG, DXF, STEP, IGES, IFC, SKP, STL, OBJ, GLB, FBX, 3DM and other 3D/CAD files. Drop any file on the viewer.
Works directly in Chrome, Firefox, Safari, and Edge
Also from Innerscene: Circadian Lab, a free lighting calculator for room illuminance, melanopic EML, and glare.
What Is a Radiance HDR File?
The format was designed by Greg Ward for the Radiance lighting simulation system. A file opens with a short text header (#?RADIANCE and lines such as FORMAT=32-bit_rle_rgbe), a resolution line such as -Y 2048 +X 4096, and then the pixels: four bytes each, three mantissas and one exponent they share. That packs a range from starlight to direct sun into 32 bits per pixel. Scanlines are usually run-length encoded. A variant, XYZE, stores CIE XYZ values in the same layout.
Most HDRI skies and studio lighting maps are published as .hdr, typically as equirectangular panoramas two units wide for each unit of height. 3D applications load them to light a scene and to show reflections. Radiance itself writes its renders as .pic files in the same format.
A screen shows 8-bit colour, so this viewer tone-maps the image: automatic exposure places the log-average brightness at middle grey, and Reinhard’s tone curve, with the white point at the 99.5th percentile, brings the highlights into range while keeping hues. The status line reports the exposure applied in EV.
Who Uses Radiance HDR Files?
3D artists and visualisers who light scenes in Blender, 3ds Max, Cinema 4D, Unreal or Unity with HDRI maps from libraries such as Poly Haven; lighting designers and researchers running daylight and glare studies in Radiance; photographers merging bracketed exposures in Photoshop or HDR tools; and anyone who has downloaded an .hdr and wants to see the sky before loading it into a scene.
Common Use Cases
- Preview an HDRI sky or studio map before loading it into a 3D scene
- Pick between several HDRI downloads without opening a 3D application
- Look at a Radiance render (.pic) on a machine with no Radiance tools installed
- Check the size and format of an HDR image from the status line
- Save a tone-mapped PNG or JPG of an HDRI for a mood board or review
Features
Opens .hdr and .pic
Radiance files are recognised by their #?RADIANCE or #?RGBE header, so HDRI downloads and Radiance renders both open.
RGBE and XYZE
Shared-exponent RGB images and the CIE XYZ variant, with XYZE converted to screen colour.
Every Scanline Encoding
Flat scanlines, the old run-length scheme and the adaptive run-length encoding current writers use.
Automatic Exposure
The log-average brightness is placed at middle grey, then a tone curve brings the highlights into range while keeping hues.
Exposure on the Status Line
The status line gives the pixel size, RGBE or XYZE, and the exposure applied in EV.
Header Primaries Honoured
A PRIMARIES line in the header is read and the colours are converted to the screen’s colour space.
Large HDRIs Handled
Pixels stay packed at four bytes while decoding, and an 8K or 16K panorama is shown at a reduced step that the status line reports.
Decoded in the Background
The decode runs in a worker with a progress bar, so the page stays responsive on large files.
Export to PNG, JPG or PDF
Save the tone-mapped picture as a PNG, a JPG or a PDF from the Export menu.
Opens From a .zip
An HDRI that arrives zipped opens straight from the archive.
Nothing Is Uploaded
The image is decoded entirely in your browser. No account, no upload, no copy on a server.
Share and Embed
Send a link that opens the image in any browser, or drop the viewer into your own page with one iframe.
Compatibility & Format Notes
Reads Radiance RGBE and XYZE images with flat scanlines, the old run-length scheme and the adaptive run-length encoding every current writer uses, with rows stored top to bottom or bottom to top. A file is recognised by its header, so a #?RADIANCE or #?RGBE file opens whatever its extension, including a Radiance render saved as .pic. XYZE is converted from CIE XYZ, and a PRIMARIES line in the header is honoured. An .hdr inside a .zip opens too. The decode runs in a background worker, and the displayed picture is capped at about 16.7 million pixels on a desktop (fewer on a phone): a 16K HDRI is shown at a third or a quarter of its size, each shown pixel the average of the block it covers, and the status line says so. Exposure is set automatically for each image and has no manual control.
Embed on Your Website
Add this viewer to your own site with a single line of HTML. Click Embed in the toolbar to generate an embed code, or use the snippet below with your own file URL.
Your Files Stay on Your Computer
Your Radiance HDR files are parsed entirely in your browser. Nothing is uploaded, stored, or shared unless you explicitly click the Share button. Shared files are hosted for 90 days then deleted.
Frequently Asked Questions
▶Why does the HDRI look darker or flatter than in my 3D application?
A 3D application uses the HDRI to light a scene; here it is shown as a flat picture at one automatic exposure, with the highlights compressed by a tone curve so the sun and the shadows both fit on screen. The stored values are unchanged, and the status line gives the exposure applied in EV.
▶Can I open a .pic file from Radiance?
Yes. The file is identified by its #?RADIANCE header, so a Radiance render opens whatever it is called. Files whose header names another program open too, as long as a FORMAT=32-bit_rle_rgbe or _xyze line follows.
▶Is the panorama shown as a sphere?
An HDRI opens as a flat image, the equirectangular panorama as it is stored, which you can zoom and pan. To see it lighting a model, load it into your 3D application.
▶How large an HDRI can it open?
The pixels stay packed as four bytes each while they are decoded, and only the rows and columns that will be shown are kept. Up to about 16.7 million pixels (8192 x 2048, or 4096 x 4096) are shown pixel for pixel on a desktop; an 8K or 16K HDRI is shown at every second, third or fourth pixel. Phones and low-memory devices use a smaller cap.
▶Is this Radiance HDR viewer really free?
Yes, completely free. No signup, no watermarks, no file size limits on the viewer (the optional share-link feature has a 100 MB upload cap). Built by Innerscene as a tool for architects, engineers, and designers.
▶Are my files uploaded to a server?
No. All parsing, rendering, and conversion runs in your browser — nothing is uploaded, stored, or transmitted by default. The Share button is the only feature that uploads a file, and only when you explicitly click it.
▶Can I convert to another format?
An HDR file is an image, so the export menu offers image formats: click Export to save the tone-mapped picture as a PDF, PNG or JPG. There are direct pages for HDR to PNG, HDR to JPG and HDR to PDF. The exported file is 8-bit; the high-dynamic-range values stay in your original .hdr.
▶Can I embed this viewer on my own site?
Yes. Click Embed in the toolbar to generate a one-line <iframe> snippet you can paste into any HTML page. You can choose whether the embed shows the viewer’s toolbar.