Reduce an image to a hard black and white decision. Every pixel’s luminance is compared against one cutoff value: above it turns white, below turns black. It is the fastest route from a photo to a stencil, a vinyl-cutter file, a rubber-stamp master, or a rough mask for another tool.
The cutoff
The threshold value runs the full 0 to 255 tonal range. Because the comparison uses perceptual luminance, a saturated blue and a dark gray of equal lightness fall on the same side of the cut, which keeps shapes coherent in colorful images. Watch the preview while dragging: silhouettes typically snap into place within a narrow band of values, and the right setting is wherever the subject separates from the background.
Edge softness
A strict threshold produces stair-stepped edges on diagonals and curves, which prints and cuts poorly at small sizes. The softness control blends a band of gray around the cutoff, in tonal units, so outlines stay smooth while the image remains effectively two-tone. Keep it at 0 when downstream software requires strictly binary pixels, such as engraving or halftone RIPs.
Invert
Invert flips the mapping so dark areas become white. Screen printers and laser engravers often need the negative of the visual: ink or burn where the original was dark. Flipping here saves a round trip through the color inverter.
Preparing the input
Threshold rewards a preprocessed image. Raising contrast or clarity first deepens the separation between subject and background, and the levels tool can pin true black and white points so the cutoff has a full range to work with. In the image workflow, a levels → threshold chain is a dependable stencil recipe.