Adjusting brightness and contrast…the proper way.

Brightness and contrast are among the most misunderstood controls on most monitors and projectors. Here’s a way to ensure that they are set up properly…

First, ignore the names. No, really, ignore what they are called – it REALLY doesn’t help.

Instead of brightness think “black level” b = blacklevel. Instead of contrast think “white level

and you will be much closer to understanding what they do.

Think of the luminance histogram in photoshop

example histogram

Brightness moves the whole histogram up and down in level.

Contrast stretches the histogram to be broader (more dynamic range) or narrower (less dynamic range).

Second, use a test chart. I am amazed at how many people try to adjust projector setting by eye without using a decent test image to make it easier

What you need is a gray-scale test chart.

Here it is as a Powerpoint file, all set to load up on your PC and display on your projector. grayscale test chart powerpoint file

Here’s it as a PNG file

grayscale test chart PNG file Stick this up and follow the instructions on-screen. It’s that easy.

You want the brightness to give you a good dark black, but still be able to just distinguish the next along black bar, and the contrast to give a good strong white, but still be able to distinguish the next along white bar. These two controls interact so be prepared to fiddle a bit.

Do this for ALL display equipment – monitors, projectors, plasmas etc. and you will be a lot closer to getting good dynamic range in your video signals.

NOTE: When you do this, you may end up saying ” now my white isn’t white enough to be seen”. That is a problem with the brightness of your projector, not with the settings. You can compensate for lack of brightness by boosting contrast, but be aware that this will blow out all the light parts of the image, which may look fine for song words, but will look terrible for video.

P.S. I made this test chart myself in Photoshop, rather than ripping off an existing one. feel free to use it, but don’t distribute it and pretend it’s yours, or sell it to anyone.

P.P.S. If you are using this test chart through a scan converter, remember that the black and white levels are going to be dependent on the scan converter settings too.


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