Perception Laboratory

Video Monitor Test Pattern Tutorials

Introduction

These test patterns can be used to assess the capability of your workstation to display the gray-scale images available on BrighamRad. The SMPTE (Society of Motion Picture and Television Engineers) test pattern [tutorial] will help you determine whether the contrast and brightness settings of your monitor are acceptable. Using the SMPTE test pattern, you can also check for limitations in spatial resolution and aliasing of your display. The BWH (Brigham and Women's Hospital) test pattern [tutorial] can be used to assess the range of gray levels available on your workstation.

Many factors and default settings can have an impact on the appearance of the images. If your monitor does not appear to adequately differentiate gray levels on these tests, you may wish to consult your computer specialist as to the best setup for your equipment.

SMPTE TEST PATTERN TUTORIAL

Choose the image format that looks best:
 [SMPTE Pattern as JPEG] [SMPTE Pattern as GIF]

 Brightness and contrast:

 The brightness and contrast of your monitor are adequately set if the 5% squares at both ends of gray scale are visible.

Using the pattern: The gray scale is shown as a series of squares in the center of the image that range from black (0%) to white (100%) in a semi-rectangle. The 0% and 100% squares (see arrows on image at left) each contain smaller squares within them that represent signal level steps of 5% and 95%, respectively. You should be able to visually differentiate the inner square from the larger square that contains it.

Be aware that it may be impossible to adjust your monitor to show both of these inner squares perfectly and equally. Most video monitors do better in showing the 95% square than the 5% square. However, you might see if reducing ambient light improves the visibility of the 5% square.

Spatial Resolution and Aliasing:

The spatial resolution (linearity) and aliasing (distortion) of your monitor are within acceptable limits if the high contrast bar patterns in the test image are distinct as simple patterns of black and white pairs.

Using the pattern: In each corner of the image as well as in the very center (see arrows on image at left), inspect the 6 squares filled with varying widths of alternating black/white horizontal and vertical lines. You should be able to differentiate all the lines, from fat to narrow (6 pixels, 4 pixels, and 2 pixels) and both horizontally and vertically.

 For more information:
You may have noticed additional features in the SMPTE test pattern. The following paper discusses use of this test pattern in detail: Nawfel RD, Chan KH, Wagenaar DJ, Judy PF. Evaluation of video gray-scale display. Medical Physics 19, 561-567 (1992) . If you would like a reprint of this paper, send a request to Philip F Judy.

 

BWH TEST PATTERN TUTORIAL

Choose the image format that looks best:
 [BWH Pattern as JPEG] [BWH Pattern as GIF]

 Continuous Gray Scale:

bwh test pattern

This test pattern is a continuous gray scale image from the center of the pattern.

 

Using the pattern: No concentric ring-like features should be present. If such features are present, the images from BrighamRad displayed on your system will be displayed at less than optimal quality.

 For more information:
We invite you to send comments to Philip F Judy regarding your experience with this test pattern.

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Updated April 8, 1997