Reduce any reference photo to the flat shapes you actually paint. Pick your number of levels below and watch the detail collapse into structure.
A photograph hands you thousands of gradations. Your eye reads them without effort, which is precisely the problem: you can see everything, so you try to paint everything, and the result goes flat and overworked.
Simplification forces a decision. When the image is reduced to four flat values, there is no gradient left to hide in. Every area belongs to one mass or another. Those masses are the painting's structure. Get them right and the detail you add later has something to sit on; get them wrong and no amount of rendering rescues it.
It is the same information you get from squinting at your subject, except it holds still and you can measure it.
The number of levels is not a quality setting. Each range answers a different question.
Pure light against pure dark, nothing in between. From the Japanese term for light–dark harmony. If the arrangement of shapes is not interesting in two values, colour will not save it. This is the fastest compositional test there is.
Light, mid-tone, shadow, and often a separate core dark. This is the working range for most painters: enough separation to describe form, few enough shapes to keep the structure legible while you work.
Now you are checking rather than planning. Useful late in a painting to find where a passage has drifted too light or too dark, and for training your eye on subtle half-tones you would otherwise round to the nearest guess.
A practical habit: plan at three, check at eight. Two passes over the same reference answer two different questions.
Before committing to a reference at all. If the notan is dull, change the crop or find another photo. That costs a minute; repainting costs an afternoon.
Thumbnail-sized. You are recording shape boundaries, not drawing. If it takes more than a few minutes, you are adding detail that belongs in step four.
Keep the simplified image beside the original, not instead of it. The simplified one tells you where the boundaries are; the original tells you what happens inside them.
Detail near the focal point, restraint everywhere else. If you find yourself rendering an area that was one flat shape in the block-in, ask whether the viewer needs it.
Simplifying to grey answers questions about value. Simplifying to a single pigment answers a different one: whether your chosen colour has the range you need. Set the base colour to Van Dyke Brown or Burnt Umber and the tool builds the levels from that pigment instead of neutral grey, which previews an underpainting or a monochrome study more closely than a grayscale conversion does.
If you only want the black-and-white check, the grayscale converter is the more direct route.
It reduces a reference photo to a small number of flat tonal shapes. Instead of thousands of gradations you get a handful of solid masses — the same thing you see when you squint at your subject. Those masses are what you actually block in when you start a painting.
Two levels give you a notan: pure light against pure dark, which tests whether the composition reads at all. Three or four levels give you a block-in plan: light, mid, shadow, and a core dark. Eight or more turns it into a detailed value map for rendering rather than planning. Most painters plan at three and check at eight.
Because overworking usually starts with copying detail that was never structural. When you decide the big shapes before touching paint, every later brushstroke either supports that structure or gets left out. Simplifying is how you make that decision consciously instead of discovering it halfway through.
Yes, and the useful level count differs. Watercolour benefits from two or three levels because you need to plan your whites before the first wash — once the paper is wet, that decision is made. Oil and acrylic tolerate more levels since you can adjust as you go, so four to six is a common working range.
No. The processing runs in your browser on your own device. The image never leaves your computer, which also means it works offline once the page has loaded.