It is difficult for the beginners of etching latte art to make well-balanced patterns by using two fluids with different viscosities such as foamed milk and syrup. Even though making etching latte art while watching making videos which show the procedure, it is difficult to keep balance. Thus well-balanced etching latte art cannot be made easily. 
 In this paper, we propose a system which supports the beginners to make well-balanced etching latte art by projecting a making procedure of etching latte art directly onto a cappuccino. 
 The experiment results show the progress by using our system.   We also discuss about the similarity of the etching latte art and the design templates by using background subtraction. Etching latte art is the practice of literally drawing on a coffee with a thin rod, such as a toothpick, in order to create images in the coffee [2] . There are several kinds of making method of etching latte art depending on tools and toppings. A method which is often introduced as easy one for beginners is putting syrup directly onto milk foam and etching to make patterns as shown in Figure 1 . The color combination automatically makes the drink look impressive by using syrup, so baristas are under less pressure to create a difficult design [8] . However, it is difficult for beginners to imagine how they ought to put syrup and etch in order to make beautiful patterns since etching latte art offers two fluids with different viscosities. On top of this, even though they can watch videos which show a making procedure of etching latte art, etching latte art made by imitating hardly looks well-balanced. It is impossible to make well-balanced etching latte art without repeated practice. In this paper, we develop a support system which helps even beginners to make well-balanced latte art by directly projecting a making procedure of etching latte art using syrup, which has high needs, onto a cappuccino. Moreover, projecting a deformation of fluid with viscosity such as syrup which is difficult to imagine as animations in order to support beginners to understand the deformation of fluid with viscosity. We indicate the usefulness of this system through a questionnaire survey and the similarity to the design templates using background subtraction. We have developed the system which supports etching latte art beginners to practice and make etching late art and also help them to understand the syrup deformation by directly projecting a making procedure and animations of syrup deformation onto the cappuccino. The participants' evaluations verified the usefulness of our system. The results of the inexperienced people's questionnaire and the participants' questionnaire show that more than 80 percent of participants made better-balanced etching latte art with our system. However, each evaluation says that two participants made betterbalanced etching latte art by themselves and they are all different participants. From this result, we confirm there are some instances that human beings suppose the etching latte art is similar to the design template even though the result of the background subtraction says it is not similar to the design template, and vice versa. In our future work, we will improve the system with considering what kind of etching latte art human beings prefer and develop a system which creates animations of syrup deformation automatically. We also handle the development factors got in the survey. Table 4 : Experimental result. Group 1 makes etching latte art by themselves firstly. Whereas Group 2 makes etching latte art with our system firstly. Table 5 : Participants' questionnaire result. Table 6 : Results of background subtraction. Similarities are represented by a number in the range of 0.000 to 1.000 (1.000 indicates totally the same as the design template).
We have developed an etching latte art support system which projects the making procedure directly onto a cappuccino to help the beginners to make well-balanced etching latte art.
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