Below is the requirement and the topic and attached is my report see you can help me to revise it to get a higher mark.Option 2: Hello, I am an engineering consultant currently working on a project in
Report of LED screen
Ⅰ.Background
The project is located at Mitchell Airport in Milwaukee, Wisconsin. Operators hope to add several large outdoor LED displays around the airport to display information and advertisements. Due to concerns regarding the screen being not attractive enough, highlighting, visually "busy" related issues, I will give corresponding explanations and suggestions based on the interaction between light and image visibility.
Ⅱ.Related knowledge
1. visual system
a. Perception of color/brightness
Human perception of light depends on retinal cells. The cone cells are responsible for the perception of light and color. The rod cells can only perceive the luminosity and not the color, but their sensitivity to light is 10,000 times that of the cones. In a weak light environment, rods play a major role, hence this leads us to not being able to distinguish colors in a dark environment. Some of the digital camera's luminous shooting mode also simulates this feature.
The three cones in the retina have overlapping frequency response curves, but the response intensity is different. They respectively are most sensitive to red (570nm), green (535nm), and blue (445nm) light, which together determine the color perception. The illuminance is proportional to the light intensity energy received by the retinal cells, but humans have different sensitivities to different wavelengths of light of the same intensity. The perceptible wavelength range is 380nm to 780nm, which is called visible light. The maximum light intensity sensitivity to green (550 nm) light occurs.
b. Human vision
The scope of human vision is approximately 220 degrees horizontal and 135 degrees vertical. However, the sharpness of the visual information that these regions can obtain are not uniform because of the two different photoreceptor cells in the subretinal segment. The reason for this difference in our field of vision is because there are two different types of photoreceptors in our eyes - rods and cones.
In order to get a more detailed and clear vision, we rely on another type of photoreceptor cells in our eyeball, the cones. Cones constitute approximately 6% of all photoreceptor cells in our eyeballs. There are usually three types of cones in the human eye, one responsible for capturing blue colour, one for green, and another for red. In order to provide a sufficient clear picture, cone cells are required to have more light to ensure proper operation. Therefore, when we observe the object in a dim environment, we lose the ability to recognize the color of the object and mainly use the information obtained by the rod, like the grayscale image.
c. Visual perception
The human eye has different abilities to receive and analyze visuals, thereby it composes perceptions to identify the physical appearance of the object, the space (distance) in which the object is located, and the change in appearance of the object. The brain receives information on the objects from the eyes and analyzes the four main types of data which are the space, color, shape, and dynamics of the objects. With these data, we can identify and show appropriate responses to foreign objects.
Furthermore, the human eye can distinguish the different shades of color of the object in the presence of light. With the contrast of light and shade, the eyes can produce a visual depth of space and see the three-dimensionality of the object. At the same time, the eyes can recognize the shape and thus helping us to identify the shape of an object. In addition, the human eye can see colors. This is known as color vision. These four kinds of visual abilities are used as one, as we explore and discern the outside world data and establish the source of visual perception.
2. Influencing factors
The main role of the human eye is to receive light and transmit light information to the brain. This light information reflected in the brain is vision. Obviously, different lights produce different vision. There are many factors that affect human vision, such as the brightness of light, the color of light, the temporal characteristics of images, the characteristics of patterns, and the size of images.
a. Brightness
The range of brightness that the human eye can sense is very wide, from a few decimal to several millions nits. The reason is that the sensitization of the eyes could automatically adjust with the intensity of the outside light. This ability to adjust is called eye adaptability. It involves the regulation of the pupil as well as the adjustment of the photoreceptor cells themselves. Of course, the human eye cannot feel such a large range of brightness at one time. When the human eye adapts to the average brightness of a certain environment, the visual range has a certain limit. In general, the ratio of the upper and lower limits of the brightness that can be resolved is 1000:1 at an appropriate average brightness; when the average brightness is very low, this ratio is only 10:1. In addition, the subjective feeling of the same brightness is not the same under different ambient brightness. For example, on a sunny day, the ambient brightness is about 10,000 nits, the resolvable brightness range is 200 to 20,000 nits, and brightness below 200 nits causes a black sensation. However, when the ambient brightness drops to 30 nits, the distinguishable range is 1 to 200 nits. At this time, the brightness of 100 nits has caused quite a sensation of light, and only a brightness below 1 nit makes a black sensation. In short, the light and dark feeling of the human eye is relative. Because of this, films and televisions that do not reflect the actual brightness of the scene can give people a true sense of brightness.
b. Light color
The color of light is usually characterized by the color temperature of the light. This is divided into three major categories: warm color <3300K; intermediate color 3300 to 5300K; cool color> 5300K. Due to the difference in light spectrum (light composition), even if the light color is the same, the color rendering of the lamp may be significantly different (such as incandescent lamps and LED lamps).
The light source color can be described by three perceptual variables.
Hue: Usually described as the "color" of a light source or object.
Saturation: The perceived color of a color or the vividness of color.
Brightness: The perceived intensity of the light source.
Normal human eyes can distinguish about seven million different colors. Different regions of the human eye have different sensitivities to colors. The center of the eye is very sensitive to color and dynamics, but the color sensitivity of the eyes is poor. Among different colors, people are more sensitive to blue than red, green and yellow. This characteristic has a great influence on visual communication.
c. Brightness and color visual characteristics
Because the human eye has a strong adaptability to brightness, it is difficult to accurately determine the absolute brightness of the stimulus. An object with the same brightness will have a different brightness when the background is different. Objects with different brightness will feel the same brightness if they have similar relative relationships with their respective backgrounds. When the background is bright, the object feels darker and when the background is dark, the object feels brighter. This subjective brightness phenomenon is also referred to as simultaneous contrast or brightness contrast.
Correspondingly there is a chromaticity contrast, such as a gray object, which looks green when the background is red, and red when the background is green. When the intensity of the illumination light changes little, the human eye does not easily feel the change in brightness, that is, the human eye has a constant brightness. When the color of the illumination light has a slight change, the color of the sensing object is constant, thus the human eye has color constancy. Actually, this is due to the fact that the human eye has a certain memory of the object's color.
When observing objects, different colors have different sense of distance. Colors with longer wavelengths will give us the feeling that the object is close, which is called the incoming color; shorter wavelength colors will make the object feel more distant, called the back color. Some colors make the object feel bigger, called the dilated color; some colors make the object feel smaller, called the contraction color. For example, the actual width of the three colors of some tricolor flags is slightly different, so that the width of the feeling is the same.
Ⅲ.Project proposal
1. Visual effects
The high-purity color has a strong impact and gives people a strong visual sensation, such as red and green, which are bright, eye-catching and easy to attract people's attention. The low-purity color which is also called neutral color gives people a soft and flat feeling, such as grey. Red, greyish green and other visual impact is weak and lack of contrast although the color is dark but full of rhyme. In terms of color brightness, bright colors give people a sense of relief. Dark colors give people a heavy feeling.
The colors are divided into warm and cool colors. Colors such as red, yellow and others which are tending to these colors give people a feeling of warmth and joy are called warm colors. The color blue, green, and colors that favor these colors give people a secluded, fresh, elegant and depressed, cold side. In addition, the colors in a screen give people a sense of lightness. Things like green or blue make people feel light, while black, gray, red, and orange items often give people a heavy feeling. After understanding the relationship between color and human visual psychology, we can use the colors flexibly for LED screens to achieve harmony and unity, with prominent themes and lively plots.
In everyday life, people are accustomed to seeing things in connection with the surrounding environment and therefore give people a sense of harmony. We should also pay attention to the color contrast on the LED screen. The full screen green grass is not good-looking. But if there is a red flower, Or a person wearing red clothes, this will immediately attract the audience’s attention. This is mainly because red and green complement each other. Under the green background, red and green will be more obvious. There are many complementary colors in the natural world. We can fully use these color relationships to improve the picture. The relationship between the color of the picture and the people's visual psychology differs with age, gender, ethnic habits, occupation, and cultural accomplishment. We should further explore the visual effects of colors so that we actively and purposefully use them to improve picture quality.
2. Visual image characteristics
Visual principles tell us that the retina has the highest visual acuity in the fovea. Another study found that when people's attention is focused on an object, the surrounding vision is blurred, and only the attention object is clear. When attention is diverted from one object to another, there is almost no intermediate process and it is direct. It can be seen that the combination of direct cuts of multiple images is the use of people's visual psychological habits. In the composition of the screen, the relationship between the balance and the weight of different images on the screen. It was found through research that (1) people are heavier than animals, (2) animals are heavier than plants, and (3) static than static weight. (4) The dark color is lighter than the light color on a light background, and the dark color is heavier than the dark color on a dark background, (5) the thick line is heavier than the thin line, (6) the bright color is heavier than the dark line, and (7) is clear The scenery is heavier than the ambiguous scenery, (8) the near thing is heavier than the distant thing, and (9) the same thing is more complete than the incomplete one. It can be seen that in order to achieve equilibrium, it must also be compatible with people's visual experience.
3. Visual perception characteristics
In a variety of complex external scenes, human vision can always quickly locate important target areas and conduct detailed analysis, while only making rough analysis or even neglecting other areas. This active and selective mental activity is called Visual Attention. Visual attention can be caused by two modes: one is a bottom-up model driven by objective content, and the other is a top-down attention model guided by subjective commands.
Bottom-up focus is mainly related to the significance of image content. Psychologists have found that targets which are significantly different from the surrounding areas are most likely to attract viewers' visual attention. Top-down attention however, is related to the dominance of consciousness and dependence on specific orders. The human eye will respond to the four visual stimuli, and then the four stimuli will generate information in the brain when the eye met with an object related to the Color, shape, depth of the object. Hence, we will respond to the location, speed, and direction of objects. Objects leave an image on the cornea. The faster the object moves, the faster the image moves. If we want to rotate around an object, we must know the object's position and trajectory.
Observing the relative motion of an object is more effective than observing the absolute motion of an object (and not comparing it with other objects). According to Gibson, humans have specific patterns of information about relative motion. Especially when an object moves, the background is intermittently covered. Gibson thinks that people will observe the motion of objects through this pattern. Another phenomenon is that the decrease in people’s sensitivity to the movement of objects is a phenomenon of selective habits. For a constant same direction or speed (similarity), the sensitivity gradually decreases, but it does not produce such a completely different movement. For example if we continue to observe the upward movement of the stripes, we will reduce the sensitivity of the upward movement (feeling that the stripes are static), but it will not affect the feeling of downward movement. Concern is forcibly transferred to a specific area.
So, when we look at the movement of an object, the complex background (relative motion) is more recognizable than the dark or neutral background and we can only see moving objects (absolute movement). Relative motion forms a special pattern, especially when the object moves. The object will cover the background that does not cover the part. Our eyes can use this mode to observe movement directly, just as we can observe depth directly.
Ⅳ.conclusion
To sum up, no matter what kind of visual factors it is , it will have a close connection with our vision. Therefore I believe that by improving the points mentioned above, it will help to increase the appeal of outdoor LED screens to the crowd. Outdoor LED, as a mass media, has the broadest coverage and acceptance as well as a close connection with the “mass” and hence is a very large influence. Therefore, reasonable colors and pure images will help to attract the public's attention.
