An “image” is rectangular array of pixels, with each pixel having a specific color. Ignoring some complexity, that color has three components: red, green, and blue.
LightBurn converts each pixel’s color into its grayscale equivalent, so each pixel has a single number representing the gray value: 0 = black and 255 = white. All of the pixels in the original image remain present, so the image size does not change.
Graphic editors alter the color of each pixel, but the rectangular image remains the same size. When you “mask” part of the image in a graphic editor, it changes the color of those pixels, but the pixels remain present.
Cropping an image in a graphic editor reduces the number of pixels by discarding those outside the crop rectangle. That’s different than masking an image, because the cropped image has fewer pixels in its rectangle.
File compression has no effect on the number of pixels, because compression only reduces the size of the file when it’s stored on disk. When the file is read back for further editing, it returns to the same rectangular size.
JPG compression (or any lossy compression) may slightly change some of the pixel colors when the file is decompressed.
Trace produces vectors at the borders of pixel regions with the same grayscale value. The result is basically a set of lines along the outlines of those regions, with no reference to the grayscale values. If the region looked like an island, the traced vectors will form a closed path.
You can do multiple tracings of the same image with different thresholds and put the resulting vectors on different layers.
You can trace the image to produce the vector path equivalent of the regions. Those vectors will be in a specific LightBurn layer with all its settings. You can apply all the usual vector operations to remove various parts of the vectors.
All of the pixels of the original image remain on a different layer (the Image layer) and will be processed by those layer settings. You can mask that image by suppressing some of the pixels, but the layer settings apply to whatever remains un-masked.
The sublayers define successive processing steps for all of the vectors on that layer; they do not apply to specific regions within that layer.
The vector layer remains separate from the image layer, with any sublayers applying only to the vectors or image on their main layers.
An algorithm is a specific way of solving a problem and is unrelated to the layer settings that define how the laser will behave as it travels across the material.
You may apply an algorithm to decide which settings to use on a particular layer: “This image will look best using Halftone dithering with 50% power at 1000 mm/min” or “These vectors should get 25% power at 100 mm/min”.
Keeping all the concepts and terminology straight definitely poses a challenge!
