First, the naive stage. This is the initial stage of sketching (painting for fun). Painters lack rational understanding of the physical state of the body and paint only by naive intuitive aesthetic impression, and their understanding and expression methods are in an unconscious and hazy state.
Second, the research stage, or the stage of painting. With the improvement of the painter's understanding and the beginning of formal training, it is required to accurately express the natural state of the body. In order to achieve this goal, the painter must study a series of natural laws such as the proportion of "shape", decency, light and shade perspective, and strive to learn and master certain sketching techniques. Because the painter's focus is on the study of the natural attributes of "shape", the feeling and performance of the aesthetic feeling and expression of the image is relatively weak, or there is a situation of paying attention to one thing and losing another, which is an inevitable phenomenon. Only with the gradual improvement of observation ability, understanding ability and expression ability will this situation be gradually improved.
Third, the mature stage, or the stage of consciously and actively portraying the image, that is, paying equal attention to "shape" and "image". At this stage, the painter not only has a deep understanding of the form and a precise grasp of the painting, but also has a clear feeling and a strong desire to express the aesthetic characteristics of the image. Therefore, the painter tries to vividly express his aesthetic feelings of the image while accurately depicting the natural characteristics of the "form", which is called "both form and spirit". At this stage, the painter's performance skills have become perfect and skilled, reaching a higher level from "having laws to being impossible".
Fourth, the stage of image expression. At this stage, the painter's understanding of the beauty of the image has made a leap, full of desire and passion to express his own subjective and unique feelings; When expressing the image, the painter is no longer constrained by the accurate reproduction of physical characteristics, and is not restricted by it, and the expression method is more bold and arbitrary. But this is different from the confusion of not understanding the body, and it is also different from the frivolous scribbling. The image represented by image sketch can not be measured by the laws and standard techniques of natural science, but its image is more reasonable in temperament, more imposing, more touching, more artistic personality and originality in expression style, and so on.
From the perspective of cognitive level, the first stage is to express the image blindly from the low-level aesthetic impression; The second stage is based on scientific laws, trying to understand and accurately reproduce the natural attributes of the form; The third stage is a stage in which cognitive ability, aesthetic ability and performance skills all reach a higher level; The fourth stage is to express the natural image subjectively from a higher level of aesthetic understanding, and the understanding and expression of the natural attributes of the form is not the main starting point at this stage.
Methodologically, the four stages are the process from "impossible" to "legal", and then from "legal" to "impossible".
In the process of learning sketch, these four stages are a gradual and natural process. Without a certain amount of practical accumulation and improvement of understanding and cultivation, it is impossible to make a hard leap across stages. At the same time, we should not be satisfied with the existing level, we must constantly strive for progress to a higher stage and dare to explore and break through.