Managing color in interactive systems

Abstract

Color in the HCI community is often undervalued as to its relationship to the user and product. Aesthetics and cultural preferences are rarely considered adequately when product and interface colors are chosen. Since ninety percent of our knowledge of the world comes to us through sight, how we respond to light is intrinsic to the nature of human interaction. In this tutorial, I will explain the perceptual, physiological, and color management principles that underlie effective visual design with color. You will learn how to apply these principles to the design of graphical user interfaces, information displays, products and virtual environments. This tutorial is directed towards interface designers, human factors engineers, usability specialists, and developers of on-line information. This course is also valuable to virtual environment designers and product designers. You should have experience in developing user interfaces, in creating and manipulating digital imagery, or in designing products and virtual environments. Vision, light and color I will explain the physiology of human perception and how it relates to image representation. I will review how the concept of gamma correction, which is ubiquitous in computer graphics and video, accomplishes “perceptually-uniform” coding yet accounts for the variance of color rendering between devices. This will give you a basis of understanding for whether two different intensity levels can be distinguished. Human vision adapts over a wide range of intensities. Your viewer’s impression of your work will be determined by her viewing conditions, so you must take into account the expected viewing conditions when you create your work. Visual acuity is at a maximum only in a small portion of the visual field. As the angle from the center of the gaze increases, acuity is reduced, but sensitivity to movement and flicker increases. To make effective use of vision in an interactive system, you must be familiar with these characteristics. Contrast sensitivity is the measure of visual acuity. Familiarity with contrast sensitivity will help you to determine how much detail you can expect your viewer to perceive. I will define contrast ratio, and explain how you can maximize contrast ratio to improve subjective sharpness. Rarely in the science of color is it explained that it is the size and shape of an object and the colors generated in the surrounding visual field that influence our perception of a color. I will explain how Dithering creates the illusion of a large number of hues and tones or colors in a limited medium. I will explain how you can employ perceptual principles to use halftoning and dithering effectively. The characteristics of vision explain which combinations of colors and patterns are effective, and which are not. The phenomenon of chromostereopsis causes blue to appear at a different depth in some circumstances; I will demonstrate this effect. I will review the reasons that blue exhibits poor sharpness, and explain why you should avoid placing detail in blue. I will also outline color deficient vision color blindness and explain how this problem can be accommodated. Color psychology and cultural preferences It’s curious to understand how societies used and understood color from a historical context. Early evidence confirmed that there is no connection between language and perception. Covered briefly, I shall see the role that color played in defining cultures. Classic color psychology suggested that there were temporary physical changes resulting from exposure