Defining layers is the next step after generating stroke lines from the image. Layers are a high level structure that associate the stroke lines with an available paint color and tool profile. Layers in this context can be thought about in the same way that you would think about layers in an image manipulation program like Adobe Photoshop or GIMP. The layers beneath will be painted first and the layers on top can overlap the layers beneath. 

I usually follow one of two thought processes when assigning a paint color to a layer: 1) I let the software automatically select the paint color that is stocked on the machine and is closest to the rgb value of the image color of the stroke lines, 2) If I want to abstract the colors of the painting, I manually select any color that is stocked on the machine.

The tool profile defines what tool is to be used and in what way. I can think of at least ten ways to orient a flat brush on a canvas to create different brush stroke effects. A tool profile defines just one of those ways.

After layers have been defined, we can create a preview image of the painting. The painting preview image below is a continuation of the example from part 1 of this project log series. It is black instead of dark green because I had the software automatically assign the stocked paint color that was the closest match to the image color. Apparently, the dark green was closer to black than the green that is also stocked. 

If after viewing the painting preview you don't like what you see, it's easy enough to regenerate stroke lines using different input parameters, assign a different paint color or tool profile, and create another painting preview image. 

Creating the painting preview image concludes the image processing component of the image to g-code process. The steps that follow are specific to developing the If Then Paint machine g-code machine movement instructions from the layer structures.