In addition to working with the PW191 alongside Dell's 2405FPW, we ran a number of diagnostic tests on the Asus panel to assess its image quality. The pictures you see below are but a sampling of the tests built-into NVIDIA's Rel. 90 Forceware drivers and Lavalys' Everest Ultimate Edition 2006. Everest Ultimate Edition in particular displays over 40 patterns to test a monitor's capabilities.
To our eyes, the Asus PW191 made it through all of tests without any major issues. In all of the calibration screens and grid tests, the PW191 produced distinct gradients and sharp, perfectly straight grids in every section of the screen. In all of the text reproduction tests, the PW191 also did well, producing clear, sharp text regardless of the color combinations used.
If there was one area where the PW191 faltered a bit, it was in the solid color tests. Gradient fills and HSL color palettes were all reproduced very well, but in the solid color tests, the lower corners of the screen were just slightly darker than the rest. This is a common problem with today's LCD monitors, however, due to uneven distribution of their back-lighting. We should also note that this issue is barely perceptible during "real-world" use.