Open an image and turn it into a solid black silhouette, on white or transparent, with a threshold slider and optional smoothing.
The converter draws the image to a canvas and classifies every pixel by brightness: pixels darker than the threshold become solid black, and the rest become white, or fully transparent if the transparent background is chosen (the silhouette shape is carried in the transparency, which suits overlays and cut-file tracing). The optional smooth pass applies a slight blur before thresholding, which rounds off jagged edges and small speckles at the cost of fine detail. It works best on images where the subject is clearly darker or lighter than its background; busy photos produce busy silhouettes, and there is no background-removal or subject detection.
Which background should I choose, white or transparent? White is easiest for printing. Transparent keeps only the silhouette shape with no background at all, which is better for layering over other designs or tracing into a cut file.
My silhouette has speckles and holes. What helps? Move the threshold slider until the subject is solid, enable the smooth pass to close small gaps, and start from a photo with stronger contrast between the subject and its background if speckles remain.