We tested 17-inch monitors that support a noninterlaced resolution of at least 1024 by 768 pixels at a refresh rate of 70 Hz, as well as 20- and 21-inch monitors that support a noninterlaced resolution of 1280 by 1024 pixels at 60 Hz. We tested all monitors using BNC connectors (if they were available).
We use a Klein optical gauge to measure convergence and a Tektronix luminance photometer to measure screen contrast. On the software side, Sonera Technologies' DisplayMate Professional and NSTL's monitor-testing software let us make detailed evaluations of image quality.
BYTE conducted more than 40 separate visual inspections on each monitor, using software-testing tools. We performed all Windows-based tests at standard resolutions for each class of monitor (1024 by 768 pixels at a 72-Hz vertical refresh rate for 17-inch monitors and
1280 by 1024 pixels at a 60-Hz vertical refresh rate for 20- and 21-inch monitors). As our test-bed, we used Graphics Pro Turbo video adapters (with 4 MB of VRAM) by ATI Technologies and Compaq Deskpro 66M computers.
DISPLAY QUALITY
For measuring overall image quality, we used three monitors of low, middle, and high quality as a control set: They all displayed the same image.
To measure image sharpness, we used an NSTL utility that produces 1- and 2-pixel-thick RGB boxes at the outside edges of the screen. We examined how well each monitor displays each box and black line. A second series of images measured the monitors' abilities to display fine vertical and horizontal lines.
Distortion manifests itself as oddly shaped screen images. Testers measure the lengths of a series of lines displayed on the monitor, and DisplayMate calculates a percentage of distortion.
The legibility test offers a real-world measurement. Testers decided at which size text was both rea
dable and legible from a standard reading distance of 24 inches.
We determined the overall display-quality score by calculating the weighted average of the image-sharpness (40 percent), contrast-ratio (10 percent), convergence (20 percent), and legibility (30 percent) tests. We combined this score with the image-quality (45 percent each) and the distortion (10 percent) scores.
Using a digital multimeter connected to the power system of the monitor, we measured power consumption when each monitor displayed a full Windows screen and when the screen was blanked. For VESA DPMS-compliant (Display Power Management Signaling) monitors, we measured power consumption in suspend mode.
FEATURES
The features we judged included the number of factory preset and user-definable modes, type of video connectors, maximum usable screen area, weight, maximum resolution, power management, and electromagnetic radiation emission specifications.
For Best Overall winners, we calculated
the weighted average of the image sharpness (40 percent), contrast ratio (10 percent), convergence (20 percent), and legibility (30 percent) tests. We weighed this score equally against the total for image quality, features, and usability (20 percent each). Distortion (5 percent) and power consumption (15 percent) are the remaining two components. The 17-inch monitors that priced under $800 and the 20- and 21-inch monitors that priced under $2000 were eligible for the Low Cost category.
Contributors
Anthony J. Lennon, Project Manager NSTL, evaluates portables, systems, peripherals, and network hardware.
Siva Kumar, Technical Analyst/NSTL, specializes in hardware and network-operating-systems testing.
Maggi Bender, Tester/NSTL.
ors@bix.com or at (603) 924-9281.
How We Tested
