"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 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."