We know that color is the objective existence of nature. It is associated with human perception (external stimulation) and human perception (memory, association, contrast...). The human eye can see that various colors are human's color feelings, and this feeling is always present in the ten color perceptions. Color and color vision are the combined effects of a series of complex physiological and psychological phenomena produced by the visual organs of a light wave factory. They involve physics, mathematics, psychology, physiology, brain filling science, and people’s art concepts. In many fields, color perception always reflects the psychological and physiological effects of color.
In the printing and copying process, the ability of color reproduction is one of the three most important factors in evaluating the copy quality. Based on faithfully reproducing the original tone, the color is accurately restored, and the entire copy quality is guaranteed. However, in the process of copying, because people are often used to relying on personal subjective experience for color identification, the depth and brightness of colors are grasped by means of (1) measurement, so that the beginning of the copying process inevitably brings about a fire-level error. For the generation of these errors, people rarely consider the influence of the operator's psychological and physiological factors. In fact, precisely because of the influence of these factors, the complexity and diversity in the work of color design and reproduction are caused. Therefore, it is necessary to discuss this issue.
First, the effect of color adaptation on color reproduction
With regard to the relationship between color and color vision, after several centuries of research by scientists, it has become the universal theory of visual two-primary color that is commonly accepted, that is, there are three kinds of visual perception of red, green, and blue in the human visual organs. Cone cells, which are sensitive to red, green, and blue light, respectively, in visible light. When external light stimulates the visual nerve endings in the human eye, the optic nerve delivers this information to the brain. The brain then synthesizes this information to produce a different sense of color.
However, the cone cells as the color-sensing function are not in the same state at any time. When the human eye looks at a certain color for a long time (usually 10-20 minutes), it will feel that this color becomes a lighter plant because of the color adaptation phenomenon caused by cones fatigue. It is precisely because the cones have the feature of fatigue and achromatism. In the process of printing and copying, when the printer looks at a certain color for a long time, the eyes will be fatigued. For example, if a printer watches green for a long time, green cells are fatigued, and a feeling of temporary deterioration occurs in green, resulting in color deviation when processing colors. This effect is most prominent in the proofing of replicas, often resulting in color fading as a result of prolonged viewing-colors during proofing, which can create errors in proofing.
two. Emotional factors influence color reproduction
In the factors that affect the human eye's ability to identify colors, there is also a person's emotional factors of color. Of course, there are no emotions in the various colors of the wooden body in the door-to-door community, but human beings gradually formed a psychological feeling of color in a long life, and kept it in a relatively fixed form. In everyday life, people are unconsciously affected by this psychological feeling. When they see red, they feel excited or annoyed. When they see green, they feel dusty and energetic. When they see blue, they feel serene and quiet. They see gray. Feeling negatively depressed, seeing black makes people feel solemn and heavy. These colors full of factory emotions are more or less affecting people's ability to identify colors objectively. In addition, in order to highlight certain topics, people often use certain exaggerated colors in the process of copying. For example, the skin color of a young girl is pink, the old farmer’s face is dark brown, the hero’s face is red, and the villain is red. In the yellow and so on, this kind of exaggerated color because of people's love for love, although in most cases it will reach the door of the effect, but because these exaggeration techniques are linked to the operator's own love and affection, Improper handling may cause color distortion. Therefore, people's emotional factors of color will cause workers' emotions to fluctuate and unconsciously produce color errors.
three. The effect of light source on color reproduction
The objects themselves do not exhibit any color, and they appear colorful because they selectively absorb the spectrum of a certain band in the light source and reflect (transmit) the rest of the spectrum when the light source hits the object. The special light-sensing mechanism in which human eyes can adapt to light stimulation can be said that "light is the only substance that enables one to perceive the form and color of objective things in ambivalence and psychological." Therefore, light source is also an important factor affecting color in print copy. The composition of the light source spectrum, the color rendering properties of the light source, the brightness of the light source, and the like are very influential in performing accurate color separation and copying operations. Same-colored rods will have different color perceptions under different light sources. Sunlight is the most ideal. In the sunlight, the color of the object is the most accurate. The color rendering of the light source is determined by the spectral energy distribution of the light source, and has a continuous spectrum similar to that of sunlight.) The color rendering of the source is good, suitable for printing jobs, to ensure the color reproduction of the distortion is small, so that the color reproduction The effect is good. In addition, the brightness of the light source can also affect the human limit color perception. The same color, when viewed in a dark and light environment, will have different appearances; mixing an artificial light source with a natural light source will also affect the appearance of the color. Therefore, the use of standard light sources is required for copy operations. For example, when performing soft proofing on the screen, in order to make the soft proofing result as close as possible to the printing result, it is required to adjust the indoor light to a standard working environment, and at the same time, since the penetration of outdoor light will affect the soft proofing effect, the doors and windows must be closed. To prevent outside light from entering.
IV. Influence of psychological and physiological factors on color reproduction
In daily life, people's ability to identify colors can also vary due to people's own mental state, emotions, the surrounding environment and age. The cones are affected by the same light stimuli, and their sensitivity varies according to the person's own emotions, spirit, and age. For a gloomy, poorly-tempered person, the bright and vibrant colors are also dull in his eyes; on the contrary, for a high-spirited and happy-looking person, the colors will be correctly identified. Force, his sensitivity to color will be high. In addition, from the age of the person, as the age increases, the color-sensing function of the person, like other functions, gradually deteriorates and becomes insensitive. Therefore, in the process of printing and copying, the spirit, emotion, age, and other factors of the printer will also affect their color identification capabilities.
In addition, there are some non-direct stimuli, such as stimulation of taste, hearing, temperature, etc., will increase the sensitivity of cones to the short-wave spectrum, reduce the sensitivity to long waves, resulting in errors in the printer's color discrimination.
Due to the influence of human psychological factors and physiological factors on the ability of color identification, it is required that the printing worker must get rid of the kind of work method that simply uses subjective experience and visual inspection to control the color reproduction of print reproduction. It should cooperate with certain dedicated measuring instruments to establish the necessary The color measurement method in the desktop access system, should also make full use of the color management system to control the various processes of color processing, and then achieve the use of data, standardized methods for color management and control purposes. (Text / Jia Liyuan)