The conversion of sensory stimuli into visual image synesthesia is a phenomenon in which sensory stimuli or cognitive pathways spontaneously and non-actively cause another perception. This phenomenon of synesthesia is rather rare and only a few people have this ability. However, some scholars believe that, more or less, everyone has had an experience of “synesthesia” at some point in their lives. Synesthesia is an important rhetorical technique in literary creation. However, with the integration of different disciplines, it has broken through the limitations of the literature, not only opening the creative road for graphic creation but also providing a wide range of thinking directions and methods. However, it is more helpful for designers to use graphics or image types in visual data [
1]. Many related studies have also confirmed that designers tend to search and retrieve a large amount of visual data and use mental image synthesis to generate design ideas [
2]. It is helpful to refer to relevant materials in the early stages of the design. Additionally, different sources of inspiration also have a significant influence on the interpretation process of the design [
3].
Regarding graphic simplification in the artistic field, Piet Mondrian’s series of well-known works, “Trees”, were conceived from an entity, such that the specific images were gradually abstracted through concrete descriptions, simplified lines, and colors. Starting from the painting on the left in
Figure 1, the outline of the tree can be clearly seen, and the middle painting in
Figure 1 is simplified such that many finely divided branches are replaced by arcs. As to the painting on the right in
Figure 1, the natural shape of the tree can no longer be seen but is instead replaced by basic geometric lines to achieve a new unity and balance. In addition, Picasso once painted a bull eleven times, from the realistic painting of the first painting to the concise lines in the middle stage, all the way to the last few lines. Although there were only a few lines, it accurately represents the shape and spirit of the bull. Picasso took a realistic image, gradually extracted important information from it, simplified it slowly, and finally obtained a nearly abstract graphic (
Figure 2).
Graphic Simplification in Comics
The authors in [
4] proposed five processes of graphic simplification (
Figure 3). From left to right, the process from realism to simplification clearly shows the two representative directions. The image on the left is more realistic, with more details that make it easier to identify, while the image on the right is more abstract and requires a higher level of perception and a wider space of interpretation. Different expressions allow the readers to become part of the comic world, making the reading experience more enjoyable for the readers, with stronger effects through graphic simplification.
“Simplification” in the field of design refers to the change from complex to simple forms, that is, the process of organizing visual information in an orderly manner. Simplification is not only a reduction of trivial details but also an adjustment after the details are reduced. Simplified graphics can be widely used at various levels, such as in logo design, comics, illustrations, posters, graphic design, etc. Many studies have also pointed out that a simplification of image design is better at attracting viewers’ attention and even improving recognition. Since designers often handle graphics with sensitivity and intuition, the visual optimization of graphic design that has been simplified is a category on its own, used to discuss how to measure whether a graphic is easily recognizable and whether the advice constitutes good graphic design. By proposing clear operating rules and values to complement the insufficiency of a designer’s intuition, novice designers are provided with a clear standard to follow. In addition, the simplification approaches can be divided into “external visual imitation” and “internal psychological mechanism”, the former of which focuses on the abstraction of external entities while the latter is the embodiment of internal abstraction. The two most commonly used modes for graphic simplification are “extraction of overall shape” and “extraction of component features” (
Figure 4;
Figure 5), both of which are often used together in the field of design [
5].
In the process of conception, the designer will spend a lot of time searching and retrieving “available data” to spark creative inspiration and enhance the speed of thinking. Among them, text, images, and other marks can be used as important tools to stimulate the thinking and associations of a designer [
6].
However, it is usually more helpful for designers to use graphics or image data [
1]. Many related studies have also confirmed that designers tend to search and retrieve a large amount of visual data and use mental image synthesis to generate design ideas [
7,
8,
9,
10,
11]. It is helpful here to refer to relevant materials in the early stages of design conception [
12]. Additionally, different sources of inspiration may also have a significant influence on the interpretation process of a given design [
3,
12,
13]. From the discussions mentioned above, it can be seen that visual image data are the largest type of data used, and are more helpful to designers. Therefore, visual image thinking has become one of the habitual thinking habits in the field of design. However, besides visual image thinking, are there any other thinking modes for designers to refer to or apply? Many studies point out that the type of source material has a significant impact on the thinking of a designer and the core value of design lies in innovation, which depends on the creativity of the designer. Regardless of the design method and process, designers should be able to manage their creativity effectively and bring their creativity into full play. If designers cannot make good use of their intelligence and creativity, the concept of development will be slowed down, which will, in turn, adversely affect the quality of life of the designers. This dilemma may place a heavy psychological burden on designers and may prevent them from producing in-depth, broad, and breakthrough design ideas. At the present stage, there is no uniform objective standard to evaluate the creativity of design education in Taiwan. Therefore, teachers often evaluate new concepts and creativity in new works based on personal opinions and discussions, where subjectivity is inevitable. In response, a small-scale expert model is developed in this study, and a combination of gray theory and a development model is established to provide a creativity evaluation standard that is highly objective and unified. By taking campus attractions as the test field, the test subject is required to experience the field through different senses before transforming the sensory stimulus into a visual image. Afterward, an observation is made on the effects of different sensory stimuli on the thinking of a designer and the differences in output [
14]. By observing the evolution of creative productivity and creative contributions, adults, in particular, are sometimes more productive than other age groups. These activity periods are also the periods when the most creative contributions were observed. In this contemporary theory, any creative response requires four elements; namely, three components of personal domain-related skills, the process of creativity, and the motivation for intrinsic tasks, which are an integral part of the work of the individual in the social environment. Creativity is the mission of designers. Despite the fact that designers have professional and design motivations in conceptual creativity, designer creativity and awareness will be restricted, the nature and the specific content of which also evolve with age. These changes exist in a model of the interaction between competence and knowledge, including the evolution of information processing, the size and relevance of knowledge bases, and expertise and complex reasoning capabilities, such as dialectical and post-formal thinking.
Multiple-attribute decision-making (MADM) is an important part of evaluation and decision-making as it focuses on solving the problem of a multi-attribute design solution. Due to the seniority of decision-makers and the uncertainty of various requirements, it is often not possible to determine the information acquired. Therefore, MADM is also classified as a decision group method that is under uncertainty. In order to solve the decision problem under uncertainty, the concept of fuzzy set theory can be integrated by using fuzzy decision-making to determine the design plan [
15]. MADM uses various evaluation methods based on the fuzzy set theory to determine the importance of a group decision-making framework. When fuzzy set theory is used for different levels of risk tolerance and comparisons, the group decision-making framework can help companies prioritize design requirements to improve customer satisfaction [
16]. Use of the integrated decision-making model to solve problems can also be combined with a fuzzy synthetic evaluation method [
17]. Regarding the high degree of similarity between evaluation and decision-making between design concepts, [
18] proposed a method, namely, the use of an intuitionistic fuzzy preference relationship (such as an intuitionistic fuzzy core and consensus winners, etc.) to assist with decision-making. To determine attribute weights, Atanassov, Pasi, and Yager (2005) [
19] suggested using an algorithm to provide accurate attribute numbering. On the other hand, Li (2005) believed that fuzzy data should be studied first, before a linear programming model is established, in order to obtain the optimal weight attributes. Another way to clearly label the substitution attributes is to use fuzzy groups to indicate the satisfaction level of the substitution to the substitution attributes [
20]. Gray theory uses the concept of “gray” to describe the attributes of the data in reality. If the data are complete, they are called “white.” If the data are incomplete, they are called “black”. If the data are somewhere in between, they are called “gray”. We may use the gray level to indicate the completion of the data in any gray event where the so-called “incomplete data” refers to (1) uncertain system factors, (2) unclear factor relationships, (3) an unclear system structure, or (4) unknown system principles. Decision-making problems often take into account multiple attributes, including the interplay between various factors. With limited resources and insufficient data, decision-makers often have to make the best decisions that meet the current situation. Unlike many tools designed to provide a complete picture of the work environment, the focuses on the factors in the work environment that are most likely to influence the expression and development of ideas. Multi-attribute decision-making (MADM) is an essential part of evaluation and decision-making because it focuses on solving the arrangement problems of multiple attribute design proposals. Because of decision-makers’ experiences and the uncertainty of various requirements, the messages acquired are usually undefined. Thus, MADM is also classified to the group of decision-making methods under uncertainty. In order to solve the problems of decision-making under uncertainty, the concept of vague set theory could be integrated by using fuzzy decisions to decide upon design proposals [
15]. Alternatively, it could be combined with a fuzzy synthetic decision model by mixing a decision-making model to solve problems [
17]. As for the high similarity of evaluation and decision-making among design concepts, [
21] proposed a method using intuitionistic fuzzy preference relationships such as an intuitionistic fuzzy core and consensus winner, etc., to help make decisions. For the certainty of attribute weight, [
22] suggested an algorithm to provide accurate attribute numbers.
Among the many types of materials, this research focuses on the most widely concerned graphic materials and explores the creative methods used in the transformation from concrete to abstract. In the process of design, the preferences of the decision-makers shall also be considered as the top priority, while graphics with more difficult and complicated designs shall be prioritized for evaluation. As we all know, each design has many parts, which are incomplete gray areas with a certain degree of similarity, all of which must be considered when making a decision. Therefore, based on the criteria of gray relational analysis (GRA), this study proposes a method for integrating sensory stimuli to address the issue of decision-making when evaluating designs. To select creativity, the design of sensory-stimulated vision using GRA is adopted as a case study for further experiments.