About High Dynamic Range

'High Dynamic Range Imaging (HDRI)' is an image capturing method that was developed through the pioneering research of Paul Debevec and Greg Ward. HDR formatted images contain per-pixel, floating-point information of varying exposure levels. They are created by capturing multiple exposure stops and combining these photos/images into a single file that essentially acts as a container, which is adjustable by software that can interpret these values. HDR images represent 'truer-to-life' brightness situations, versus traditional methods of changing an images' overall brightness values which can often lead to washed-out results.

An example for comparison of normal exposure adjustments on a digital image. The image on the right is the default image value. Note the underexposed image on the left and how a lower values darkens the scene entirely:

An example for comparison of HDR format exposure adjustments. Note the image on the left with a focus on the sun. This mimics real world results of adjusting the aperture (opening) on the lens of an actual camera, whereas the previous image ignored this intensity information:

Usage in 3D Applications and Gaming Environments

In 3D computer graphics (CG), HDR has found a prominent place as a method of 'Image-Based Lighting' (IBL) - that is a method to light a scene(s) by using real-world imagery as part of a 3D environment. Compared to traditional 'studio lighting setups' of using lights from specific directions and points, this form of lighting represents the 'real' world conditions by enveloping a scene from multiple directions. HDR often gives subtle nuances in color, extraordinary control over exposure values, and lends life-like photorealistic qualities to 3D scenes and models.

It is worth nothing that another form of HDR called openEXR is under continual development by Industrial Light and Magic (ILM.) EXR can produce a higher dynamic range that goes well beyond the perception of the human eye. It has been used in many ILM movies and the software is available to the public free of charge.

HDRSource HDR Images

In the HDRSource libraries, we have digitally created high quality HDR images in order to meet some of the needs other HDR libraries didn't provide. These images are high resolution with a greater control over lighting situations, environment backgrounds, and overall color balance. Unlike most photo-based HDR images, these do not have some of the limitations of background object size, blur resulting from slightly misaligned compositing, and chromatic aberration from lens distortion. Like most HDRs, every single one is unique.