Pencil sketch converter
Choose a photo and the tool draws its edges as soft pencil lines on white paper. Set how dark the lines are and how fine, and choose plain graphite or a coloured-pencil look. The full-size file is made in your browser.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose or drop a photo.
- Move Line strength to make the lines lighter or darker.
- Change Line softness for finer or broader lines.
- Pick Graphite on white or Coloured pencil, then download.
How it works
For each pixel the tool takes the grey value g and the blurred negative b of the picture, and computes g × 255 / (255 − b), capped at 255. In an even area g and 255 − b are equal, so the result is 255 (white). Near an edge the blurred negative is brighter or darker than the pixel itself and the result drops, which draws the line. The line strength then scales how far the value is pulled from white.
Example
A flat grey area of 100 has a negative of 155, a blur of 155 and the result 100 × 255 / 100 = 255, so it is white paper. The edge between black and white halves comes out nearly black on the dark side.
Tips
- Raise the strength above 100 % for a bold, inked look and lower it for a faint pencil.
- Large photos are fine: the sketch is computed on the full-size picture when you download.
Frequently asked questions
How does a photo become a sketch?
The photo is turned grey, a blurred copy of its negative is made, and the grey picture is divided by that copy (a colour dodge). Flat areas become white and only edges, where the two differ, stay dark.
What does the blur radius change?
A small radius draws thin, sharp lines along fine edges. A larger radius gives broader, softer shading around bigger shapes. The radius is kept in proportion when the preview is smaller than the saved file.
Which photos work best?
Portraits and objects with clear edges and good contrast. A busy photo with a lot of texture gives a very dark sketch; lower the line strength or raise the radius.
What is the coloured pencil look?
The sketch is multiplied with the original colours, so white paper stays white and lines darken the colour beneath them.