It is used to define an external image on any texture channel. These images can be RGB, Alpha or Greyscale. It is an option you will often use during texture creation. You may need to make some adjustments depending on the picture you have selected for efficient use of the GPU and Vram. We will discuss what these settings are in "Image Texture Settings".
how to use
Open the Node editor and prepare the setup as you see in the picture below. In this setup, both greyscale and rgb images are used. It's a standard setup, all you have to do is create the pictures and "Image Texture" nodes you need and connect them to the relevant channels. In the picture below, "real surface displacement textures" are used for image textures that give a rocky-sand view. These textures are very high quality and they are commercial. You can find it online. You can also prepare your own textures in the 3rd party softwares (eg. bitmap2Material). In the example setup, the "transform" node is also attached to all image texture nodes. So you can do all transform operations with a single node for images of the same size and resolution. However, this method may not be suitable for different resolutions.
IMAGE TEXTURE SETTINGS
From here you can define any image texture.
Controls the brightness of the image.
Controls the luminance of the input image.
Inverts the color values of the image.
Sets the behavior of the space around the image if the image does not cover the entire geometry. You can see all the border mode options in the picture below.
From here you can determine the type of your image. Normally, the entire image is converted to RGB values regardless of the image type you upload. For example, if you upload a greyscale image and leave the option here as "Normal", it will still be converted to RGB values. To use the GPU Vram effectively and efficiently, you can set the options here according to the type of your image texture. If you've uploaded greyscale or alpha image, do not forget to choose "Float" or "Alpha" here.
When you previously loaded a 32 bit exr or HDR image into Octane the image was automatically converted to 16 bit (for GPU optimization purposes). There was no way to control it. With these options you can now use the channel format of your image texture. There are 4 options: Auto, Uint8, Float and Half. If you choose Auto, Octane decides to the bit depth of the loaded image texture. So you will use it automatically whatever the original bit depth of your image file. If you select Uint8, you will use the image with 8 bit depth, which is ideal for jpeg or targa pictures. If you choose Float, you will use 32 bit depth. This is also a choice when you are installing hdr or 32 bit exr pictures. Half is only for using 16 bit depth.
So suppose you upload a 32 bit HDR image and you want to use this image without loss, in this case the format you should choose is "Float". But as a disadvantage, you will be using much Vram and GPU power. If your system is strong we recommend to use HDR or all other images with a 32 bit depth in "float" format. So you can get rid of the color clipping problem. However, when you upload an HDR image with 32 bit depth, do not select Uint8 for optimization purposes. It only makes the picture poor quality.
UV TRANSFORM & PROJECTION
These two texture nodes explained in detail in the relevant sections.