PNG to HDR Converter
Convert PNG to HDR in your browser. PNG files usually come from screenshots, design exports, logos and web graphics; HDR is the better fit for 3D lighting and environment maps. You get a Radiance RGBE (.hdr) file, with the 8-bit sRGB values converted to linear light. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
PNG expected · other image formats also work
How to use PNG to HDR
- 1
Add your PNG files: drop them here, choose them, or paste from the clipboard.
- 2
Pick the colour that replaces transparent areas, since HDR has none.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .hdr files one at a time or together as a ZIP.
Why use Aback Images for png to hdr
Where the HDR goes next
HDR opens in Blender, Photoshop, Houdini, Unreal Engine, Unity and Affinity Photo.
HDR next to PNG
Both sides are lossless, so the size depends on how well the HDR encoder handles this picture compared with the PNG's lossless DEFLATE with a prediction filter chosen per row.
Written without a lossy pass
The HDR is written losslessly, so the pixels decoded from the PNG arrive unchanged, apart from precision beyond 8 bits per channel.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
PNG vs HDR
What changes from PNG to HDR
Encoding: the PNG uses lossless DEFLATE with a prediction filter chosen per row; HDR uses run-length encoded RGBE scanlines, and the download is a Radiance RGBE (.hdr) file, with the 8-bit sRGB values converted to linear light.
Bit depth: 1, 2, 4, 8 or 16 bits per channel in the PNG; HDR allows an 8-bit mantissa per channel sharing an 8-bit exponent (RGBE), 32 bits per pixel, and the HDR written here has RGBE, 32 bits per pixel. 16-bit PNGs from photo and scientific software are reduced to 8 bits per channel.
Colour: RGB, greyscale, or an indexed palette of up to 256 colours in the PNG; HDR supports linear RGB (or XYZ in the XYZE variant), written here as linear-light RGB.
Transparency: the PNG stores it as a full alpha channel, so edges and shadows can fade smoothly; the HDR has none, so transparent areas are filled with the colour you choose.
Metadata: the PNG can carry text chunks, an ICC profile, physical resolution and EXIF in an eXIf chunk; HDR can carry a text header with FORMAT, EXPOSURE and optional comments, but nothing is copied across.
About PNG
PNG stores pixels losslessly with full alpha transparency. It is ideal for screenshots, logos, UI and anything with sharp edges, but photos saved as PNG are several times larger than JPEG.
A PNG opens with an 8-byte signature and is a chain of chunks, each with its own CRC: IHDR (size, depth, colour type), optional PLTE and tRNS for palettes, one or more IDAT chunks with the compressed rows, and IEND.
PNG files usually come from screenshots, design exports, logos and web graphics.
About HDR
Radiance .hdr stores high dynamic range light values, widely used for 3D environment maps and HDRI lighting.
A Radiance file starts with '#?RADIANCE' (or '#?RGBE'), text lines such as FORMAT=32-bit_rle_rgbe and EXPOSURE, a blank line, a resolution line like '-Y 2048 +X 4096', then the scanlines.
When converting PNG to HDR makes sense
HDR is the better choice for 3D lighting and environment maps, while PNG suits screenshots, logos, graphics and anything that needs transparency.
HDR strengths: True high dynamic range; Standard for HDRI environment maps. Drawbacks to weigh: Needs tone mapping to view on normal screens.
Limitations
- No range is added: the HDR holds the 8-bit picture in linear light, and nothing in it is brighter than the original white.
- 3D software treats the file as linear light, so an ordinary photo used as an environment map may need its exposure raised to light a scene well.
More conversions
Related tools
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Convert PNG to JPG in your browser, with transparency filled in a colour you pick. Batch, private, no uploads.
Convert PNG to WebP in your browser, ready for images on websites and in apps. Batch, private, no uploads.
Convert PNG to AVIF in your browser, ready for maximum compression on modern websites. Batch, private, no uploads.
Convert PNG to PDF in your browser, one PDF page per image. Batch, private, no uploads.
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Convert PNG to SVG in your browser, traced into real vector paths. Batch, private, no uploads.
Convert PNG to EPS in your browser, with transparency filled in a colour you pick. Batch, private, no uploads.
Frequently asked questions
Does converting PNG to HDR lose quality?
HDR is written losslessly, so the pixels are stored exactly as decoded. 16-bit PNGs from photo and scientific software are reduced to 8 bits per channel.
What happens to transparency when converting PNG to HDR?
PNG stores transparency as a full alpha channel, so edges and shadows can fade smoothly. HDR has no alpha channel, so transparent pixels are composited onto a solid colour, white unless you pick another. To keep transparency, convert to PNG, WebP or AVIF instead.
Does saving as HDR make a real HDRI?
No. A real HDRI is merged from several exposures. This file holds an 8-bit image in linear light, so 3D software reads it correctly, but it has no more range than the source.
Which apps open HDR files?
Blender, Photoshop, Houdini, Unreal Engine, Unity and Affinity Photo. It does not open in web browsers.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.