Pixel¸ or Pel

Picture element; the smallest spot on the screen that can be resolved as having a different brightness or color from what is next to it. The "number of pixels vertically" is equal to the number of scan lines; for example if you block off all but a narrow vertical stripe on the screen, you will see a series of dots, one per scan line. For a computer screen or digital video, the screen is divided into several hundred "grid positions" horizontally as well; a pixel must be exactly one of the grid positions, not half of one and half of the next. For analog TV pictures, we can say that the number of pixels horizontally is equal to the maximum number of alternating black and white dots that can be reproduced all the way across the screen, which equals the aspect ratio times the number of lines of resolution horizontally.