High dynamic range imaging (HDR) is an important technology for photographers. It is a collection of techniques that allow a wider dynamic range of luminances between the lightest and darkest areas of an image.
The human eye can adapt to luminances from 0.000,000,1 cd/m² up to 1,000,000 cd/m², and can cope with a luminance range of 1:1000. However, computer displays only offer a contrast of approximately 300:1. This means that the luminance offered by a computer monitor falls significantly short to what the human eye can actually process.
HDR software allows computer graphics to offer the full real world levels of illumination, with darker darks and brighter lights, while at the same time increasing the amount of lighting detail displayed in all areas of the image. While standard image formats utilizes 8, 16 or 24 bits with applied gamma and color space, the HDR image format extends the bit depth up to 96 bit in a linear color space. Additionally, HDR images can be photometrically correct.
HDR images are normally generated by combining multiple normal images of the same scene taken with different intensity levels, or as the result of creating a global illumination rendering.
To provide an insight into the quality of software that is available, we have compiled a list of 11 top quality open source HDR applications. Hopefully, there will be something of interest for anyone interested in HDR imagery. Only free and open source software is eligible for inclusion.
Let’s explore the 11 HDR tools at hand. For each title we have compiled its own portal page, a full description with an in-depth analysis of its features, a screenshot of the software in action, together with links to relevant resources.
| HDR Imaging Software | |
|---|---|
| RawTherapee | The Experimental Raw Photo Editor |
| OpenEXR | HDR image file format and HDR utilities |
| Hugin | Panorama photo stitching program |
| pfstools | Command line HDR manipulation programs |
| Luminance HDR | Provides a workflow for HDR imaging |
| tev | High dynamic range image comparison tool |
| HyperHDR | Ambient lighting implementation for television and music sets |
| HDRView | Depth-map and high-dynamic range image viewer |
| Radiance | Lighting simulation and rendering system |
| HDRMerge | Combine two or more raw images into a single raw |
| CinePaint | Works with 16-bit and floating point pixels for HDR imaging |
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