Underground History Monitor Tests

Please note: Most of these tests were designed back in the era when most people used the old style CRT monitors. They're not as relevant in this age when the vast majority are using LCD displays - but I've left this page here (for now) for historic reasons. This PLUGE pattern test is largely irrelevant for LCD displays.

1. PLUGE Pattern

If you have a CRT monitor, adjust the brightness so that you can just see a dark square towards the left of the above frame, but can't see the second square to the right. This test works on CRT and plasma screens, but does not work on TFT and LCD screens.

The PLUGE (picture line-up generation equipment) pattern test enables you to set the "black level" of your monitor. If the brightness setting it too low, images will appear too dark and detail will be lost. If it is too bright, then bright images will wash out and images meant to be dark will reveal compression artifacts and could swamp out other detail (e.g. the background image on my pages interfering with the white text).

This is a tricky test to perform - especially if your monitor has on-screen graphics when going into monitor settings.

It works like this. Maximise this window so that it fills the screen. You should adjust the brightness of your monitor such that you can only just see a single dark square to the left inside the frame above. If you see none, the setting is too low and images will appear too dark. If it is too bright, you will observe two squares, a light one and a dark one.

Strictly speaking, this test was designed for television pictures, where it is possible to have a black darker than the standard permits for calibration, but also serves as a good method of ensuring a computer monitor is set to a correct black level setting.

If the resulting images appears too dark, now try adjusting the contrast setting on your monitor to compensate.

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