Channels of an image synthesis

We have often spoken of “Transparency channel” de una imagen, which describes the points or “pixels” of said image which do not have an associated color and thus are “transparent”.

In Blender, transparency canal, can get other channels, appropriately combined, defining the final image.

Among the channels that can be cited as most important in the final outcome of the composition can quote:

• Color
• Shades
• Diffused light
• Transparency …

An image channels

Let's see an example containing graphic information some of these channels. Suppose the next scene consists of a cube textured, some colored spheres (one transparent and one reflective pure) and a plane on which cast shadows.

Reference Image

The image is composed of combined information can decompose in basic channels, such as transparency containing (background) not the hay. This channel will generally have two possible values ​​for each pixel, indicating if you are transparent (black color in the image) are the opaque (white):

Transparency channel

Another important channel is the one that contains the color information of each pixel. We represent the image with solid colors that represent.

Color channel

The color channel is influenced by the illumination of diffuse type. This effect determines the channel lighting “Diffuse”.

Channel diffuse lighting

About diffuse illumination can add effects like glare, that are within what is called the channel “speculate”.

Channel speculate

Both diffuse and specular light depend on the surface normal at each point, and the relative position of the lighting points (lights). Information shown in normal images that are called “normal maps”.

Normal map

For three-dimensional feel are necessary shadows, which establish the relative position of objects in space. We generate an image with cast shadows on themselves and one above each other.

Shadows cast

In the case of reflective surfaces, mirror-effects, have an additional channel

Reflected light channel

Other channels as containing information about the light that has passed through liquid crystal or a refractive index.

Refractive channel

The depth of the objects or the camera distance (With valor) are important to determine other maps of interest, such as fog or atmosphere.

Fog channel

As you can see an image contains a lot of information. These channels will be helpful when composing some pictures with others in phases postproduction and special effects (VFX). Later we will use these channels with the editor of nodes in Blender to simplify the process of generating a scene, separating the bottom of the characters.