AVS Forum Special Member
Join Date: May 2008
Location: San Francisco - East Bay area
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The real issue here is that discs of test patterns will NEVER tell you what the RIGHT Contrast setting is. All they will tell you is the highest setting you can use that does not clip white. Which in itself is a fairly trivial thing since there's no image detail in white above the 235 video level (you should be using 16-235 / limited range when working with consumer video displays versus computer monitors where you may want to use full-range 0-255 video depending on how the monitor works...if the "monitor" is just a lightly modified consumer display, it might still work better in 16-235 mode).
Those discs do tend to make you think they are going to help you find the RIGHT setting for Contrast but that is absolutely positively NOT TRUE. To find the RIGHT setting for the contrast control you have 2 choices.
Before you set Contrast it will be useful to know the usable adjustment range (which may not be the full adjustment range the manufacturer offers), the disc can be useful for that.
If you have a colorimeter and calibration software, you measure the light level of 100% white. If you are in a completely dark room, you will probably want 30-35 fL for 100% white. You cannot achieve that without a meter and software to measure the display. For a room with a low level of light in it, you probably want 35-40 fL of light. If the room is brightly lit (like daylight coming in), you might want 55-65 fL or even more.
If you do NOT have a colorimeter and calibraton software, all you can go by to determine the RIGHT contrast setting is whether or not you notice eyestrain after 2-3 hours of viewing the screen. If you do NOT detect any fatigue around your temples and eyes after 2-3 hours you are either darker than optimum or right close to the recommended levels mentioned above.
If you find it is always difficult to escape eyestrain, and if you want to improve your perception of how black the blacks are on your video display, you'd be an ideal candidate for a color-balanced (i.e. D65 which is NOT the same thing a 6500K color temperature...you can have 6500K that is NOT D65 and possibly not even remotely close to D65) bias light behind the video display.
Eyestrain comes from the black/dark area surrounding a bright video display screen... your eye "sees" the black and tries to open your irises, but you immediately "see" the bright video display again and your brain tries to close your irises. So there's a constant battle in your head over what your irises should be doing... open, close, open, close.... that's what leads to the feeling of eyestrain after 2-3 hours. You want to eliminate that constant battle and the only way to do that is to get the white level set correctly. Without a colorimeter, all you can do is guess at what the right Contrast setting is by noticing whether you are experiencing eyestrain after a period of use. If you are, you can turn down the luminance of the video display until the eyestrain feeling stops. Or you can add a bias light which should allow the display to be brighter without eyestrain. Of you get a meter and KNOW you are using a decent light level -- and some still find that they just can't eliminate the feeling of eyestrain even with 30 fL in a dark room, so those are great candidates for bias lighting behind the video display.
"Movies is magic..." Van Dyke Parks
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