Linearity Orthogonal Diagonal Orthogonal Linearity - The orthogonal linearity test puts up a grid of evenly spaced horizontal and vertical lines that can be used to ensure that images are not displayed in warp space. A flexible, thin metal or plastic ruler can be used with this test screen. A straight edge of thick paper may be easier to fit on to the screen surface. Line the ruler or straight edge up with a grid line to see if it curves or is straight, as it should be. Use the ruler to measure the distance between parallel lines at several points and see that spacing between them remains equidistant.
Linearity is primarily an issue for computer monitors that use CRTs.
Some less expensive projection systems may exhibit linearity problems. Flat panel displays do not have a linearity issue. Diagonal Linearity - The diagonal linearity test puts up a grid of evenly spaced sloped lines that can checked with a ruler for straightness. See the orthogonal linearity test above for additional details. In Pixels Measure Lookup Table Pixel Size Measuring Grid - This test screen is used to measure browser window size and on browsers that allow full screen page display, screen size measurement in pixels.