Convert a photo or illustration into line art (black lines on white) right in your browser. It uses the classic pencil-sketch color-dodge method: (1) convert to grayscale, (2) invert the tones, (3) Gaussian blur to smear them, and (4) color-dodge the original grayscale with the inverted blur, leaving only the contours as dark lines. Where Canny edge detection produces a technical white-on-black edge map, this tool gives a natural drawing-like line art (black on white), as if sketched on paper with a pencil. It's handy for roughing out AI illustrations, making coloring-book base lines, previewing a ControlNet lineart preprocessor, or preparing tracing material. There are three controls. Detail is the blur amount — raise it for finer, thinner lines, lower it for thicker, softer ones. Line strength is a gamma curve — raise it to make lines darker and crisper, lower it for paler lines. Threshold at 0 keeps the soft pencil-sketch tones; raising it binarizes the image at that brightness into solid black-and-white lines (good for coloring or tracing). Tick "White lines on black" to invert, producing the white-line map a Stable Diffusion ControlNet (lineart preprocessor) expects. The output matches the source pixel size (very large images are processed at up to 2048px on the long side to stay responsive) and saves as a PNG. All computation happens in your browser — the image is never sent to any server or API.