Video signal formed by a series of 8 bars colored (white, yellow, cyan, green, magenta, red, blue and black). It is used as a  reference for adjusting brightness, contrast, color intensity and color balance. Normally generated electronically. Color saturation and tint for NTSC video signals can be calibrated with saturation and hue adjustments. (PAL signals require no hue adjustments.) An SMPTE color-bar pattern is used for this step, along with a blue color filter. Each of the eight vertical color bars also represents a level of picture brightness, from the white bar on the extreme left to the dark blue bar on the right. If you reduce the color saturation control completely on a projector or monitor, these bars will turn into an eight-step grayscale.