April 1999
19 inch Monitors Face Off
By Liz Levy
We put 12 of the newest 19 inch CRT monitors in a face to face battle. Which ones stand out from the pack? Check out the results of our tests.
Letýs face it, even with falling prices not all of us can afford a 21" CRT monitor, especially for hundreds or more desktops. There are also space considerations. If you require a large display and a high resolution without the high price tag, then feast your eyes on this new batch of 19ý monitors that offer generous displays at significant savings.
To put 12 of the newest 19ý monitors to the test, we set them up in our Imaging & Document Solutions Lab. Our test was based on DisplayMate for Windows Multimedia Edition Version 2.0 from Sonera Technologies (Rumson, NJ www.displaymate.com). The software generates a variety of test pattern screens that target specific monitor characteristics such as geometry, screen uniformity, focus, moire, and color and grayscale display. We selected 20 of these patterns to create our own Imaging & Document Solutions Test Script.
For a glimpse of the software and our testing procedures, Soneraýs Web site offers several free demo programs and sample test patterns for download.
Our test bed was a 266 MHz H-P Vectra equipped with a Revolution IV 32MB, 250 MHz DAC, AGP graphics board from Number Nine (Lexington, MA www.nine.com). The board supports 2D graphics resolutions at up to 1920 x 1200 77 Hz refresh rate with 16-bit color depth. All monitors we tested were run at 1280 x 1024 85 Hz with 32-bit color depth.
We viewed six monitors at once by connecting each to an Extron (Anaheim, CA 714-491-1593) P/2 DA6 Plus VGA splitter attached to the H-P Vectra. This enabled us to do side by side comparisons. Any monitors that displayed poor performance in any of the tests were isolated and connected directly to the PC.
In addition to the performance tests, we also evaluated the overall design and adjustment controls. This meant spending time playing with the controls and reviewing the design.
The monitor controls should give you enough features to adjust and correct any problems in the image. They should be intuitive and easy to navigate on screen. The standard control categories to look for are brightness, contrast, geometry, size and position.
Some of the monitors tested included additional controls to adjust focus, convergence, moirý, color temperature and manual degaussing. Degaussing demagnetizes a monitorýs tube to reduce picture distortion. The more controls you have, the more you can fine-tune the image and picture quality.
Many of these 19ý monitors have shorter chassis or necks for a smaller foot print. These models bring larger monitors to smaller desktops and cubicles.
Four monitors tested feature totally flat CRT screens. Flat screens reduce glare and geometric distortion but can also produce a concave look. Manufacturers have different approaches for correcting this by either adding a very slight curvature to the glass or by adding a curve to the internal screen surface or aperture grill. These flat screen monitors are a bit more expensive than traditional CRTs.
The Test Procedure
Using DisplayMate Software form Sonera Technologies, our Imaging test script pinpointed several monitor characteristics.
Average Picture Level (APL): A higher intensity of white raises the APL and can affect the intensities of black and grays.
Black Level: The monitors should be able to produce a true black while also handling the most subtle variations or scales of gray.
Color Balance and Convergence: If one of a monitorýs three electron guns (red, green, blue) is turned up higher than the other two, you will get a color imbalance and see a tint on the screen. The three CRT beams must also converge precisely on the phosphors to produce a single color image without loss to image detail.
Color Tracking and Saturation : This tests the monitorýs ability to display gradations of color intensity without altering tint. A monitor with good color saturation can display slight color changes distinctly.
Focus, Contrast and Legibility: Images should appear in focus from the center of the screen to the corners. There should be a minimum of color streaking and halo, which undermine contrast. Text should be legible at various point sizes on white and black backgrounds.
Gray-scale Shift: This measures the change in the brightness level of gray areas on screen when the adjacent area alternates between dim and bright states. Well-engineered monitors show little or no change.
Geometry: This refers to the monitorýs ability to reproduce various shapes accurately and without distortion. Problems with geometry include poor linearity, shape variations and a disproportionate aspect ratio.
Moirý: These are undesirable wavy lines that can be caused by a mismatch between the pattern of a monitorýs shadow mask or aperture grille and a horizontal line pattern of an image. Line patterns that virbrate in the display are also a common occurrence due to natural interference.
Screen Regulation: This exhibits the effects of brightness on display stability. A high intensity of white can cause images to expand or contract.
Screen Uniformity: When displaying a solid color, the screen should look the same from the center to the corners without dark spots or tints.
Video Bandwidth: This is the monitorýs ability to refresh the screen in a given amount of time. A high bandwidth translates into support for higher resolutions and higher refresh rates.
White Level Saturation: The brightest whites should not be saturated and the monitor should be able to display a range of white intensities.
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