HDR & EXR to JPG Converter

About the HDR & EXR to JPG Converter

Open Radiance HDR (.hdr, .pic) and OpenEXR (.exr) images — HDRI environment maps, renders from Blender and other 3D programs, and merged HDR photos — and turn them into pictures you can share. Set the exposure in stops (or let Auto pick it from the image’s average brightness), choose a tone-mapping curve — ACES filmic, Reinhard or a plain clamp — and the display curve, then save a JPG, PNG, 16-bit PNG or WebP. Panoramas twice as wide as they are high also open in a 360° view that you can drag around, so you can check an HDRI from the inside before you light a scene with it.

EXR files are decoded in your browser with the lossless codecs (NONE, RLE, ZIPS, ZIP, PIZ) and the lossy PXR24, B44 and B44A, with half and 32-bit float channels, alpha, render layers and single passes such as depth. Nothing is uploaded.

Common uses

• Previewing and sharing renders without opening the 3D program or compositor.
• Checking HDRI environment maps — brightness, the sun, the horizon — in a 360° view before lighting a scene with them.
• Making JPG thumbnails of HDRIs for a library, website or store.
• Turning merged HDR photos saved as .hdr or .exr into a JPG or PNG.
• Looking at single EXR passes such as depth, masks or IDs.

Tone mapping: ACES, Reinhard and clamp

HDR images store light, not finished pixels: values above 1.0 (brighter than white) are normal, and the sun in an HDRI can be thousands of times brighter than the sky. A screen or a JPG can only show 0 to 1, so the values are multiplied by 2^EV (the exposure) and then compressed by a curve:

• ACES filmic uses Krzysztof Narkowicz’s fit of the ACES filmic curve, x(2.51x + 0.03) / (x(2.43x + 0.59) + 0.14), on each channel (ACES Filmic Tone Mapping Curve). Highlights roll off like film, and very bright colours lose some saturation. The fit is pre-exposed so that 1.0 comes out at about 0.8; Narkowicz notes that multiplying the input by 0.6 (about −0.7 EV) matches the original ACES curve.
• Reinhard is the global operator from Reinhard, Stark, Shirley and Ferwerda, Photographic Tone Reproduction for Digital Images (SIGGRAPH; University of Utah technical report UUCS-02-001), equation 4: Ld = L(1 + L / Lwhite²) / (1 + L), applied to luminance, with each pixel’s colour scaled by the same factor. As in the paper, Lwhite defaults to the brightest luminance (after exposure), so nothing burns out; enter a lower white point to let the brightest areas clip.
• Clamp cuts every value above 1.0 — what a plain image viewer shows.

The result is encoded with the sRGB curve (IEC 61966-2-1) or a plain power curve with the gamma you set. Auto exposure maps the image’s log-average luminance (equation 1 of the paper) to middle grey, the paper’s key value of 0.18.

Supported files

• Radiance HDR (.hdr, .pic): Greg Ward’s RGBE encoding (Real Pixels, Graphics Gems II) as described in Radiance File Formats — RGBE and XYZE pixels, flat, old and new run-length scan lines, and all eight resolution-string orientations. Pixels are read as mantissa × 2^(exponent − 136), as Blender, stb_image and Bruce Walter’s rgbe.c do; test files written by Blender, ffmpeg and ImageMagick decode to exactly the values Blender reads.
• OpenEXR (.exr), following the OpenEXR File Layout: scan-line and tiled images (the full-resolution level of mipmapped files) and every part of multi-part files — Blender 5 saves each render pass of a multilayer EXR as a part of its own; half, float and uint channels; NONE, RLE, ZIPS, ZIP, PIZ, PXR24, B44 and B44A compression, ported from the OpenEXR library’s own code (BSD-3-Clause). Test files written by the OpenEXR library — through Blender and OpenImageIO — decode bit for bit to the values the library reads, for each of these codecs and for tiled, mipmapped, multi-part and offset-window files.
• Layers and passes: groups of R, G and B channels, such as ViewLayer.Combined or diffuse, appear as colour layers (the Combined, beauty or RGBA layer first), and X, Y, Z passes such as normals are shown with X, Y and Z as red, green and blue; other channels (Z depth, masks, IDs) can be shown one at a time in grey.

EXR alpha is premultiplied, as the format defines; PNG and WebP keep straight alpha, so colours are divided by alpha when alpha is kept, and without alpha the image is shown over black.

16-bit PNG and the 360° view

16-bit PNG keeps 65,536 levels per channel instead of 256, which avoids banding in skies and soft gradients when you grade or retouch the image further. It is still a display image — the tone curve and the sRGB or gamma encoding have been applied, and the file is marked with an sRGB or gAMA chunk to say so — not an HDR file that keeps values above white.

The 360° view shows equirectangular panoramas (twice as wide as they are high) from the inside, as a renderer uses them for lighting: the middle of the image is straight ahead, and dragging, the arrow keys or the buttons turn and tilt the view. It uses the current exposure and tone curve, at up to 2,048 pixels wide.

Limitations

• Images up to 40 megapixels (for example 8,192 × 4,096) and files up to 1 GB, as the whole image is decoded in the browser tab; very large images need a desktop browser with enough memory.
• DWAA, DWAB and HTJ2K compressed EXRs, deep EXRs, subsampled (luminance/chroma) EXRs and B44 files with perceptually linear channels cannot be decoded — the page says so; re-save them with ZIP or PIZ compression.
• Only the full-resolution level of tiled (mipmapped) EXRs is shown, and deep parts of multi-part files are left out. Pixels outside the data window are not drawn.
• Colours are treated as linear Rec. 709 / sRGB primaries. EXR chromaticities and Radiance PRIMARIES and COLORCORR header lines are not applied; a Radiance EXPOSURE line is reported, not applied.
• JPG and WebP files are made by the browser’s canvas encoder, and canvases have a size limit (on iPhone and iPad 8,192 × 8,192 pixels); if a full-size export fails, choose a smaller size. PNG and 16-bit PNG files are written without a canvas.

Privacy

Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.