Reduce any reference to pure light and dark and find out in under a minute whether the composition is worth painting. Set the levels to 2 below.
Give yourself three or four values and almost any arrangement starts to look plausible. The gradation does the work, and you never find out whether the underlying structure was any good.
At two values there is nowhere to hide. Every part of the image is either light or dark, and what remains is the arrangement of shapes. That is why the notan is a test rather than a study: it answers one question, and it answers it before you have spent anything.
The word is Japanese, and it means light-dark harmony. The idea predates every tool on this page by several centuries.
Dark shapes that join into a few larger masses give the eye a path. Darks broken into many small islands read as confetti, and usually mean the subject has no clear structure to find.
Roughly equal areas of light and dark tend to feel static. Something closer to a third against two thirds gives one of them the upper hand, and the picture a subject.
Shapes that survive several threshold settings are the real structure. Shapes that appear at one setting and vanish at the next were never load bearing, and painting them will not make them so.
Once the composition passes, raise the count. Three or four values turn the test into a block-in plan, which is what the image simplifier is set up for. Eight or more turns it into a value map for checking a painting that has drifted.
If the notan fails, change the crop or find another reference. That costs a minute. Discovering the same thing three hours into a painting costs the afternoon.
A notan is a study that reduces an image to two values, pure light and pure dark, with nothing in between. The word is Japanese and means light-dark harmony. Stripping out every mid-tone leaves only the arrangement of shapes, which is the part of a composition that either works or does not.
Because two values cannot flatter a weak composition. Three or four give you enough gradation to make almost any arrangement look plausible, and that is exactly the wrong thing when you are deciding whether an arrangement is worth painting. If it holds at two, it will hold at twenty.
Interlocking shapes of unequal size, with the darks connected to each other rather than scattered as isolated islands. A notan that reads as confetti usually means the subject has no clear structure. One where light and dark are roughly equal in area tends to feel static, so an uneven split is normally the stronger one.
Start where the tool puts it and move it until the shapes look most decisive. There is no single correct point, because it depends on your subject and on which reading you want. Moving the threshold and watching the shapes reorganise is itself the exercise: it shows you which parts of the composition are stable and which only exist at one setting.
Before anything else, while changing your mind is still free. A notan takes under a minute and tells you whether a reference is worth several hours. Painters who skip it tend to discover the composition problem when the painting is half finished and expensive to abandon.
No. The study is computed in your browser on your own device. The image never leaves your computer.