HDR to PNG Converter

You have a Radiance .hdr file and want a picture without JPG artefacts, for documentation, a texture check or a tutorial. This converter tone-maps the file to eight bits and writes a PNG, entirely in your browser. The wide brightness range of the original does not survive, but the PNG keeps the 8-bit result exactly.

Drop images here, click to choose, or paste with Ctrl+V
HDR files · many files at once · nothing is uploaded
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Free to use on any site. Paste the code where you want the tool to appear. It runs inside the page; visitors' files are processed in their own browser and are not uploaded.

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WordPress and most site builders have a "Custom HTML" block where this code can be pasted. The embed keeps a small link back to CalcMaster.

How to convert HDR to PNG

  1. Add your HDR files by dropping them, clicking the drop zone or pasting.
  2. The output format is already set to PNG. Adjust quality or size if you need to.
  3. Press Convert and compare the original and new size for each file.
  4. Download each file or all of them as a ZIP.

When to convert, and when not to

  • You want a clean, artefact-free image of an environment map or lighting probe.
  • A site, slide or ticket accepts PNG but not .hdr.
  • You are documenting a scene and need the exact pixels of the preview.
  • Do not feed the PNG back into a renderer as a light; it has lost the extra brightness.

What changes

  • The wide Radiance range is tone-mapped to eight bits per channel.
  • A GAMMA header in the file is respected, so already-curved data is not curved twice.
  • XYZE files and rotated layouts are not supported and give a message.
  • The PNG is lossless from the 8-bit data and has no quality slider.
  • Header text and metadata are not written.

A lossless file from a lossy step

Tone mapping decides which parts of the brightness range stay visible. After that, PNG stores the eight-bit result without further loss. This is the main reason to choose PNG over JPG for an .hdr preview: smooth skies and soft gradients do not pick up compression blocks.

Smooth gradients in lighting images

Lighting panoramas often contain wide, smooth gradients such as skies and soft light falloff. JPG can show banding or blocks in such areas at low quality settings, while PNG will not add any. The cost is size, because smooth photographic gradients do not compress as tightly in PNG. Compare the sizes shown next to your own results.

Cropping and shrinking

Environment maps can be very large. Use the resize option to lower the pixel size before saving, since PNG has no quality control to make files smaller. A reduced copy is often enough for a thumbnail, a gallery or a note in a document.

What the original keeps and the PNG drops

The .hdr keeps brightness information for rendering. The PNG does not. Keep the .hdr file wherever you use it for lighting, and use the PNG only as a picture of it.

Checking the PNG against the original

Open the PNG next to the .hdr in the program you normally use, at the same size. The brightest spots, such as a sun or a window, will look flatter in the PNG, because their extra brightness is not stored. Check the layout, the colours and the overall mood instead. If they match, the PNG is a faithful 8-bit picture of the file, and you can keep using the .hdr for lighting.

Using the PNG as a reference

A PNG is handy as a reference picture in a design brief, a tutorial or a shared document, where the reader only needs to see what the lighting looks like. It also works as a thumbnail for a library of environment maps. For these uses a reduced size is usually enough, so try the percent option before you convert a whole folder.

Privacy: your files stay on your device

  • The tool decodes, resizes and encodes your pictures with your browser. The files are never sent to a server.
  • To check it yourself: open the browser developer tools (F12), open the Network tab, convert a file, and look for any request that carries your image. You will see none.

Frequently asked questions

Does PNG keep the HDR range?

No. The PNG holds eight bits per channel, so the extra brightness is not stored.

Why is the PNG larger than a JPG would be?

PNG is lossless, and smooth photographic areas take more space that way. Choose JPG in the options for a lighter file.

Can it open XYZE .hdr files?

No. Only the standard RGBE form is read, and other encodings give a clear message.

Why does it look different in my 3D software?

The software uses the full range for lighting, while the PNG shows a tone-mapped view.

Can I convert several .hdr files together?

Yes. They are processed one by one and can be saved together as a ZIP.

Can I use the PNG as a thumbnail for my maps?

Yes. Convert with the resize option to get a small PNG that is easy to browse.

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