A simple high dynamic range (HDR) image viewer using matplotlib.pyplot for displaying and imageio for reading/writing. It’s all in python, easy to extend.

alt text


  • Displays HDR images (e.g., .exr and .hdr images). I use imageio for reading images, so anything imageio supports can be displayed.
  • Toggle gamma correction (g)
  • Adjust exposure (scroll). Hold shift to change the exposure faster.
  • See pixel values under the mouse cursor
  • See general statistics (original resolution, min/max pixel value, spherical mean, spherical standard deviation, contrast)
  • Toggle between a diffusely convolved image and the original image (d). Make sure you do this for HDRI’s intended for image-based lighting. Note that the first time you press d, it will take a few seconds to compute the diffuse image.
  • Save your edited image (o), saves to ./output/ or ./dist/HDR_Viewer_PyPlot/output/

Running via python

You’ll need to pip install modules including imageio (with EXR support)
, matplotlib, numpy, and cv2.

The run:
python [string filepath] optional: [int resizeWidth]

For example:

python ./images/grace-new.exr 512

resizeWidth is useful if you have very large images that will be too slow to display.

Packaging into an Executable

It can be useful to compile into an executable, so then you can have your .exr or .hdr images always open with this program.

pip install pyinstaller

pyinstaller HDR_Viewer_PyPlot.spec --noconfirm

This will package into dist/HDR_Viewer_PyPlot. Point your HDR images (i.e., right click the file, “Open with” > “Choose another app”, and select dist/HDR_Viewer_PyPlot/HDR_Viewer_PyPlot.exe

When rebuilding, you might need to manually delete dist in case of permission denied issues (e.g., rmdir /s dist and maybe rmdir /s build).


View Github