The node itself is very simple. In the Input texture pin, you connect the texture you want to perform color grading on. In the LUT pin, you should connect a Lookup table.
What is a Lookup Table?
A lookup table is an image that tells the computer how it should modify the color of each pixel. You can see an example of a LUT above. If you download the above image here, import it into Lightact and connect it via an Image reader node to the LUT input of the Color grading node, you’ll see that the output doesn’t really change.
An image of the layout.
That’s because the above image is a neutral LUT. It doesn’t cause any changes, but you’ll need it to create LUTs that will.
However, if you use this LUT (also shown below).
Then you’ll get a bit different outcome.
How do you create a Lookup table?
There are many ways to create a Lookup table, but what we’ll show here is a workflow using Adobe Photoshop software. Basically, it has 3 steps:
- Modify the texture you want to perform color grading on by using adjustment layers.
- Open the neutral LUT and copy the same adjustments layers over to it.
- Save the modified LUT as a png and use it in Lightact as an input to Texture color grading node.
So let’s start with step number 1 and download the sample image. Open it with Photoshop.
Insert a Hue/Saturation adjustment layer. The exact look of this will vary depending on which version of Photoshop you are using, but the general approach is the same.
Change the hue of the image however you want (you can move the other 2 sliders as well if you want).
Open the colorGrading-neutral.png in Photoshop and drag the adjustment layer from the sample image to the LUT.
Once you have the adjustment layer in your LUT image you’ll see that it changed as well. If you created more adjustment layers you should copy all of them. You can save the modified LUT now, but don’t overwrite the original.
Great, now we just need to import the sample image and the new LUT and connect the layout as shown below:
As you can see the look inside Lightact is exactly the same as the one in Photoshop.