High Dynamic Range Rendering: Unlocking the Visual Spectrum: Advanced Techniques in Computer Vision

By Fouad Sabry

What is High Dynamic Range Rendering

High-dynamic-range rendering, also known as high-dynamic-range lighting, is the rendering of computer graphics scenes by using lighting calculations done in high dynamic range (HDR). This allows preservation of details that may be lost due to limiting contrast ratios. Video games and computer-generated movies and special effects benefit from this as it creates more realistic scenes than with more simplistic lighting models.

How you will benefit

(I) Insights, and validations about the following topics:

Chapter 1: High-dynamic-range rendering

Chapter 2: Rendering (computer graphics)

Chapter 3: Global illumination

Chapter 4: Multi-exposure HDR capture

Chapter 5: Tone mapping

Chapter 6: Per-pixel lighting

Chapter 7: Bloom (shader effect)

Chapter 8: Image-based lighting

Chapter 9: High dynamic range

Chapter 10: Wolfgang Heidrich

(II) Answering the public top questions about high dynamic range rendering.

(III) Real world examples for the usage of high dynamic range rendering in many fields.

Who this book is for

Professionals, undergraduate and graduate students, enthusiasts, hobbyists, and those who want to go beyond basic knowledge or information for any kind of High Dynamic Range Rendering.

• Language: English
• Publisher: One Billion Knowledgeable
• Release date: May 4, 2024

Book preview

Chapter 1: High-dynamic-range rendering

Using high dynamic range lighting calculations, high dynamic range rendering (HDRR or HDR rendering) creates photorealistic images in computer graphics (HDR). In this way, details that could otherwise be lost owing to low contrast can be kept. More realistic sceneries can be created in video games, CGI films, and special effects animations as a result of this.

Developers of graphics processing units Nvidia provides a three-point synopsis of HDR's justification: Things can be as dark as they need to be or as light as they need to be in order to see details, and vice versa.

In 1985, Greg Ward pioneered the use of high-dynamic-range imaging (HDRI) in computer graphics with the release of his free and open-source Radiance rendering and lighting simulation program. For over a decade, HDRI progress stalled because to constraints in processing speed, data storage, and acquisition techniques. The technology to practically implement HDRI has only recently emerged. These two studies established the groundwork for making high dynamic range (HDR) light probes of a place and then employing those probes to illuminate a generated scene.

Since then, high dynamic range images (HDRI) and high dynamic range lighting (HDRL) have found widespread usage in 3D scenes where the incorporation of a 3D item into a real environment necessitates the use of light probe data to create plausible lighting effects.

Spencer's research was the basis for an HDRI postprocessing shader used in the 1997 video game Riven: The Sequel to Myst. When Epic Games demonstrated Unreal Engine 3 and Valve announced Half-Life 2: Lost Coast in 2005 at E3, along with open-source engines like OGRE 3D and open-source games like Nexuiz, the phrase once again acquired widespread usage.

HDR rendering has the advantage of retaining finer details in high-contrast scenes. Without high dynamic range (HDR), images with too much black or white are automatically adjusted. The technology converts these to a floating point value of 0.0 for completely black and 1.0 for completely white.

The use of additional perceptual cues to boost apparent brightness is another facet of HDR rendering. Optical phenomena like reflections and refractions, as well as transparent materials like glass, are also affected by HDR rendering's treatment of light preservation. Very strong lights (like the sun) are limited to a luminance value of 1.0 in LDR rendering. In this case, the outcome must be less than or equal to 1.0 when this light is reflected. In HDR rendering, however, extremely strong light sources can have a brightness greater than 1.0 to represent their true values. This allows for realistically bright light sources to be reflected off of objects.

The average dynamic contrast ratio that the human eye can detect is roughly 1,000,000:1. It takes time for the iris to adapt and for the body to undergo the modest chemical changes necessary for adaptation to occur (e.g. the delay in being able to see when switching from bright lighting to pitch darkness). The eye has a narrower static range, on the order of 10,000:1. This, however, is still outside the normal operating range of most display devices.

Although many brands boast impressive figures, plasma screens, LCD screens, and CRT screens can only produce a small fraction of the contrast ratio found in the real world, and even then, only under perfect conditions. Under typical viewing conditions, the actual content's simultaneous contrast is far lower.

Automatically dimming the lighting for low-light settings is one way to improve LCD monitors' dynamic range. Digital Fine Contrast is LG's name for this tech; The dynamic range of OLED displays is higher than that of LCDs; they are comparable to plasma in this regard yet consume less electricity. HDTV color space is defined by Rec. 709, while UHDTV color space is defined by Rec. 2020, which is more expansive but still not full.

Blooming is caused by light dispersion in the human lens and is seen by the human brain as an area of increased brightness. A strong light source in the background, for instance, can cast a shadow on front elements. You can use this to trick others into thinking the bright spot is brighter than it actually is.

Flare is caused by the diffraction of light in the human lens and manifests as rays of light coming from very nearby lights. Because of the limited viewing angle, it is most obvious on point lights.

HDR rendering systems, in order to accurately depict what the human eye would see in the produced scenario, must map the whole dynamic range of the human visual system onto the capabilities of the device. To represent