01色度学基础.ppt

Fundamental Jian Wang SEIE-TJU jianwang@tju.edu.cn Index Human Vision System CIE Chromaticity Diagrams Color Space EYE AND COLOR 人眼成像过程 EYE AND COLOR electromagnetic spectrum EYE AND COLOR Simplified representation of the human eye EYE AND COLOR cones and rods EYE AND COLOR Cones(锥状细胞) are concentrated around the fovea(中心凹) and are very sensitive to color with high spatial resolution Rods(杆状细胞) are more spread out and are sensitive to low levels of illumination with low spatial resolution. EYE AND COLOR Approximately 65% of these cones are sensitive to red light, 33% to green light and 2% to blue light Absorption curves for the different cones have been determined experimentally Receptoral Color Information The colors that we perceive in our environment are divided into two classes: chromatic(彩色) and achromatic(灰度). The chromatic colors can be characterized by three components: hue, saturation, and luminance Hue describes the type of chromaticity a color has and is indicated generally with words such as red, yellow, and blue. Saturation describes the purity of a color, or the measure of the degree to which a pure color is diluted by white light. As saturation decreases, colors appear more faded. Luminance indicates the strength of light sensitivity as it is connected to each color sensitivity. The greater the strength of the lighting, the lighter the color appears. Receptoral Color Information Hue Saturation Value Trichromatic Theory additive color mixture (Red, green, blue) and subtractive color mixture (cyan, magenta, yellow) Metamerism Metamerism(同色异谱) implies that two objects that appear to have exactly the same color may have very different colors under differing lighting conditions. The wavelengths of the primary colors C1, C2 , and C3 are standardized internationally. They are the spectral colors with the wavelengths 700nm (red), 546nm (green), and 435 nm (blue). Metamerism 同色异谱现象简单来说就是颜色相同，而光谱组成不同。一种颜