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Real-time Tone Mapping

It's all about the dynamic range.

A Lot of people generally can confuse High Dynamic Range (HDR) and tone mapping, but even if they’re related, they are different techniques.

In this article you’ll be able to understand the difference between them and to know the advantages of using tone mapping in real-time rendering.

Tone Mapping is one of the features that U-Render offers you as post-processing filters. It’s a powerful tool to prevent that scenes burnt out where the brightness of lights and materials is highlighted.

You can use it in image processing and computer graphics to convert HDR images, that have a high-contrast value, into low-dynamic range, by preserving visual perception. In comparison, HDR images reproduce a greater range of luminosity than what is possible with standard digital imaging or photographic systems.

The aim of both methods, tone mapping and HDR, is basically simulating the human vision by yielding the same visual sensation as viewing a scene in the real world.

Before discovering the powerful advantages of this feature, just do a step behind with us.

How does the human visual system work?

Humans are capable of seeing a huge range of intensities, from daylight to night luminance.

Visual perception begins as soon as the eye focuses light onto the retina, where it’s absorbed by a layer of photoreceptor cells. These cells are a type of neurons specialized for photo-transduction. They convert light into electrochemical signals. We can divide them into two types: rods and cones, named in this way for their shape.

Human vision is not equal at all light-intensities, because of the different sensitivities of the rods and cones. Rods are responsible for night vision, but haven’t capability to distinguish different colors. Cones work in daylight and are responsible for color vision. In detail there are three different types for each sensitive to a certain wavelength of light. The combination of these three response-curves makes up the impression of color.

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Tone Mapping: Advantages and Characteristics

The aim of this particular feature is to give your renders a realistic touch. It works in scenes where lights or special materials, like metal, have a high brightness.

U-Render provides 3 methods of tone mapping to reproduce the human visual perception. You can choose your setting between:

  • Linear: it’s the simplest and fastest mapping.
  • Exponential: it provides a different luminance because it doesn’t use a linear function but a logarithmic one.
  • Reinhard: it assures a high-quality result in terms of visual pleasure and maintaining image integrity.

The real-time technology of U-RENDER permits you to change operators and check immediately the results, without noise and waiting times.

Thanks to tone mapping, you are able to improve the realism of your scene by imitating the behavior of human perception.

The correct shine of a metallic armor, for example, can define if your artwork has reached the wow-effect. If yes, it will give the whole scene a balanced and convincing moodSee the picture below.

Realtime tone mapping news

You can combine tone mapping with other post-processing effects that U-RENDER offers, like Motion-Blur and Depth-Of-View.

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