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بيشوي حنا ماهر 5/1 Fri 18 Dec 2009, 4:48 pmFigure 2
Light and pigments mix differently to form colors. Since the human visual system has three color sensors, it is possible to pick three suitable colors and generate the other colors by mixing these. By convention, the primary colors of light light are chosen to be red, green and blue (RGB). Because they produce white light when they are added together, color mixing of light is called "additive." Any two primaries of light can be combined to form a secondary color - magenta (red plus blue), cyan (green plus blue), and yellow (red plus green). When a secondary is mixed in proper proportions with its opposite primary, the resulting light will be white. Therefore, any primary color is considered to be complementary with the secondary color produced by mixing the other two primaries. Yellow and blue are complementary colors of light - as are cyan and red, and magenta and green (Fig.2).
In pigments, however, a primary color is defined as one that subtracts or absorbs a primary color of light while transmitting or reflecting the other two. For example, the pigment that absorbs red light and reflects blue and green would be called cyan. So, the primary pigment colors (sometimes called subtractive primaries) are cyan, magenta, and yellow - the secondary colors of light.
The color appearance of an object or surface clearly depends on the light used to illuminate it. Often daylight is considered a "standard" but it is obvious that the color of "daylight" changes with the position of the sun in the sky, how cloudy or overcast it is and also which direction of the sky we are sampling, e.g. northern sky or southern sky. In specifying lamp color, the first thing that must be decided is how" warm" or how "cool" a lamp is to be selected. This is generally a subjective decision entirely. The color temperature of the lamp in Kelvins specifies the degree of coolness or warmth of the light source. Another color rating of lamps is the Color Rendering Index (CRI). Lamps with high CRI tend to have a "natural" look no matter what the color temperature. These two terms are explained in more detail later.
Light and pigments mix differently to form colors. Since the human visual system has three color sensors, it is possible to pick three suitable colors and generate the other colors by mixing these. By convention, the primary colors of light light are chosen to be red, green and blue (RGB). Because they produce white light when they are added together, color mixing of light is called "additive." Any two primaries of light can be combined to form a secondary color - magenta (red plus blue), cyan (green plus blue), and yellow (red plus green). When a secondary is mixed in proper proportions with its opposite primary, the resulting light will be white. Therefore, any primary color is considered to be complementary with the secondary color produced by mixing the other two primaries. Yellow and blue are complementary colors of light - as are cyan and red, and magenta and green (Fig.2).
In pigments, however, a primary color is defined as one that subtracts or absorbs a primary color of light while transmitting or reflecting the other two. For example, the pigment that absorbs red light and reflects blue and green would be called cyan. So, the primary pigment colors (sometimes called subtractive primaries) are cyan, magenta, and yellow - the secondary colors of light.
The color appearance of an object or surface clearly depends on the light used to illuminate it. Often daylight is considered a "standard" but it is obvious that the color of "daylight" changes with the position of the sun in the sky, how cloudy or overcast it is and also which direction of the sky we are sampling, e.g. northern sky or southern sky. In specifying lamp color, the first thing that must be decided is how" warm" or how "cool" a lamp is to be selected. This is generally a subjective decision entirely. The color temperature of the lamp in Kelvins specifies the degree of coolness or warmth of the light source. Another color rating of lamps is the Color Rendering Index (CRI). Lamps with high CRI tend to have a "natural" look no matter what the color temperature. These two terms are explained in more detail later.
