The native resolution of a LCD or other flat panel display refers to its single fixed resolution. As an LCD display consists of a fixed raster, it cannot change resolution to match the signal being displayed as a CRT monitor can, meaning that optimal display quality can be reached only when the signal input matches the native resolution. An image where the number of pixels is the same as in the image source and where the pixels are perfectly aligned to the pixels in the source is said to be pixel perfect.
While CRT monitors can usually display images at various resolutions, an LCD monitor has to rely on interpolation (scaling of the image), which causes a loss of image quality. An LCD has to scale up a smaller image to fit into the area of the native resolution. This is the same principle as taking a smaller image in an image editing program and enlarging it; the smaller image loses its sharpness when it is expanded. This results in noticeable quality loss and the image is much less sharp.