All the lines are constructed with clear curves.
The clear curve is a chain of arcs.
As an arc is a part of a circle the line can be quantified.
In this case the arc model is suitable for comparing.
Twelve circles are enough to reconstruct these drawings( the quater-circle model).
Counting all the arcs which belong to the same circle, the list( the harmonious index) can be made.
It is easily noticed that some circles are used more to make the structure harmonious.
I have already shown that the other Ukiyoe-artists like Toyokuni and Shunei used straight lines and curves for the contour of a face.
Besides it seems that they did not know the harmonious effect by many arcs of the same curvature.
The number of the arcs which belongs to the same circle can be counted to make a list: the harmonious index.
So I call this method of drawing as twelve circle method( after the twelve tone method).
When an experienced artist draws a curve he is conscious of its curvature.
So every part of any line becomes an arc.
The number of the basic circles for the arcs becomes small because of our limited ability to distinguish curvature difference,
From the same reason the number of finger holes of ancient flute anywhere is limited.
Musical sounds are perceived as quanta, but only genius noticed that artwork has also basic units.
Though ornamental patterns are noticeably made of units they did not think that ornament and artworks are of the same genre.
Perception of shape is not analog but digital, which is a necessary condition to form the basic intelligence （visual grammar）.
The left illustration is a page of Hokusai Manga which was published in 1812.
And the right one is one of the most wellknown among Sharaku's prints: the portrait of the Theater Manager named Shinozuka Urayemon.
Sharaku's technique is completely same as Hokusai's.
The twelve circle method can be developed independently by geniuses like Picasso only after long experience.
But no amateur like Noh-actor Saito Jurobei can do.
Using the principle of Occam's Razor it is certain to say that Sharaku is Hokusai.
(to be continued)
