Colour Adjust Shader

Colour Adjust Shader

Overview

The Colour Adjust shader allows you to define the black point or white point of the shader or function nodes assigned to its Main input.

It is similar to a levels control in the sense that sliding the black point or the white point raises or lowers the darkest and brightest values.

Increasing the value of the Black point slider darkens the surface.

Decreasing the value of the White point slider lightens the surface.

Adjusting both Black and White points can darken and lighten parts the surface that are outside the values chosen by the sliders.

Settings:

• Name: This setting allows you to apply a descriptive name to the node, which can be helpful when using multiple Colour adjust nodes in a project.
• Clamp below black: When checked, the colour values that are below black (sRBG 0,0,0) are set to black. This is useful when adjusted values become negative values, for example (-1.0,0.5,0.0). Prior to being output the negative values are reset to (0.0,0.5,0.0).
• Clamp above white: When checked, the colour values that exceed beyond white (sRGB 255,255,255) are set to white. This is useful when adjusted values become "super-bright", for example (5.0,0.75,1.0). Prior to being output the super-bright values are reset or clamped to (1.0,0.75,1.0).

Input Levels Tab

Input Levels Tab

This tab contains settings for manipulating the colour values from the Main input. Use the “Black point” slider to define the colour value you wish to be the lowest value and the “White point” slider to define the colour value you wish to be used as the highest values. Values can extend beyond 0 and 1.

In the example images below this Power fractal pattern was used as the source texture.

Fractal noise pattern used as texture in example images below.

• Black point: As the Black point is increased a surface becomes darker. For example, if the White point is set to 1 and the Black point is set to 0.5, the surface will be twice as dark.



White point = 1. Black point values set to -1.0, -0.5, 0.0, 0.5 and 1.0

• White point: As the white point is decreased a surface becomes brighter. For example, if the Black point is set to 0 and the White point is set to 0.5, the surface will be twice as bright.



Black point = 0. White point values set to 2.0, 1.5, 1.0, 0.5 and 0.0

Gamma Tab

Gamma Tab

• Gamma:



Gamma point at 0.0, 0.25, 0.5, 0.75 and 1.0

Usage

The Colour adjust shader is very versatile, and listed below are a number of practical uses for it.

Tinting: By setting the black or white point to a complementary colour of the Main Input colour values a surface can be tinted.

Colour adjust shader at default settings.	Colour adjust shader White point = sRGB 0,255,255.	Colour adjust shader White point = sRGB 255,0,0.
	Colour adjust shader Black point = 0,255,255	Colour adjust shader Black pint = 255,0,0

Masks: By increasing or decreasing the black or white point values, shaders and function nodes used as masks can be expanded or contracted.

Colour adjust shader with default settings.

Colour adjust shader Black point = -10.

Colour adjust shader White point = 10.

A shader is a program or set of instructions used in 3D computer graphics to determine the final surface properties of an object or image. This can include arbitrarily complex descriptions of light absorption and diffusion, texture mapping, reflection and refraction, shadowing, surface displacement and post-processing effects. In Terragen 2 shaders are used to construct and modify almost every element of a scene.

A single object or device in the node network which generates or modifies data and may accept input data or create output data or both, depending on its function. Nodes usually have their own settings which control the data they create or how they modify data passing through them. Nodes are connected together in a network to perform work in a network-based user interface. In Terragen 2 nodes are connected together to describe a scene.