terminology depending on cultural background of the painters and authors, and sometimes the term violet is used and placed in between red and blue on the traditional color wheel. In a slightly different variation, on the color wheel, purple is placed between magenta and violet. This shade is sometimes called electric purple (See shades of purple). In the RGB color model, named for the colors red, green, and blue, used to create all the colors on a computer screen or television, the range of purples is created by mixing red and blue light of different intensities on a black screen. The standard HTML color purple is created by red and blue light of equal intensity, at a brightness that is halfway between full power and darkness. In color printing, purple is sometimes represented by the color magenta, or sometimes by mixing magenta with red or blue. It can also be created by mixing just red and blue alone, but in that case the purple is less bright, with lower saturation or intensity. A less bright purple can also be created with light or paint by adding a certain quantity of the third primary color (green for light or yellow for pigment). On a chromaticity diagram, the straight line connecting the extreme spectral colors (red and violet) is known as the line of purples (or 'purple boundary'); it represents one limit of human color perception. The color magenta used in the CMYK printing process is near the center of the line of purples, but most people associate the term "purple" with a somewhat bluer tone, such as is displayed by the color "electric purple" (a color also directly on the line of purples), shown below. On the CIE xy chromaticity diagram, violet is on the curved edge in the lower left, while purples are on the straight line connecting the extreme colors red and violet; this line is known as the line of purples, or the purple line. Pigments Hematite and manganese are the oldest pigments used for the color purple. They were used by Neolithic artists in the form of sticks, like charcoal, or ground and powdered and mixed with fat, and used as a paint. Hematite is a reddish iron oxide which, when ground coarsely, makes a purple pigment. One such pigment is caput mortuum, whose name is also used in reference to mummy brown. The latter is another