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iPod touch What uses more energy, a black pixel or a white one?

H

hierobryan

macrumors 6502a
Original poster
Jan 4, 2008
622
0
earth/jupiter
Place answer here ->

Just curious....I'm at work reading the Bible on my Touch.

by the way, I'm talking about an LCD screen.
 
I think a black pixel requires more energy on a LCD since the backlight remains on and the pixel is completely blocked requiring maximum energy. The white pixel only has the backlight with no energy required to block the light put out by the backlight.

For a CRT, it would be reversed since no light at all is sent to a black pixel.
 
I thought that it was only CRT's that had a difference in power consumption and that LCD had no difference in how much energy is used on all different colors...

and no, you're stealing from your employer. He isn't paying you to steal from you.
 
I'm pretty sure that, once a pixel on an LCD is set to a certain color, no more energy is needed to maintain that pixel until its color needs to be changed. That is, a black pixel requires just as much energy as a white pixel, but that the energy is consumed in changing each pixel to a new color and is only consumed during that update.

The real drain is the backlight, which is always shining and always blasting its way through every single pixel on the screen. That's why black isn't really "black" so much as it's "really really really dark grey".
 
ChrisBrightwell said:
I'm pretty sure that, once a pixel on an LCD is set to a certain color, no more energy is needed to maintain that pixel until its color needs to be changed. That is, a black pixel requires just as much energy as a white pixel, but that the energy is consumed in changing each pixel to a new color and is only consumed during that update.
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What you're describing is true of power budgeting for E-Ink displays. LCD's, however, always require some amount of power even just to preserve their image. It may well be that they use less power to display a static image than to display a changing one, though; but I don't know.

Remember, though, that there is no such thing as a "white pixel". There are groups of 3 pixels packed in really close to each other - one each for red, green, and blue. As you vary the relative intensities of each of these three sub-pixels, your brain mixes them together to create the perception of different intermediate colours.

The real drain is the backlight, which is always shining and always blasting its way through every single pixel on the screen. That's why black isn't really "black" so much as it's "really really really dark grey".
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Yep.
 
iLoveiPod said:
White pixel. Thats why theres http://www.blackle.com
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I wonder how much MORE energy is wasted performing the power saved calculations. Not to mention the energy required to run the additional servers. I understand the good intentions of using the site, but don't blindly accept something as being true because someone says it is. You might end up hurting the cause you're trying to help.
 
uaaerospace said:
I wonder how much MORE energy is wasted performing the power saved calculations. Not to mention the energy required to run the additional servers. I understand the good intentions of using the site, but don't blindly accept something as being true because someone says it is. You might end up hurting the cause you're trying to help.
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Hmm..Where to start. Well, first off, these calculations can probably be done on a solar calculator...so lets not be so dramatic here. Second, i dont use the site at all, its just something i stumbled across. Third, its just a website! No need for all your philosophical babble about blindly accepting things and hurting the world. Thats all.
 
iLoveiPod said:
Hmm..Where to start. Well, first off, these calculations can probably be done on a solar calculator...so lets not be so dramatic here. Second, i dont use the site at all, its just something i stumbled across. Third, its just a website! No need for all your philosophical babble about blindly accepting things and hurting the world. Thats all.
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haha, my "babble" wasn't aimed at you or anyone in particular. Just a week prior to stumbling across this thread, a friend of mine showed me the site and was all excited because he was saving energy. He knew he was saving energy simply because it was written on the page.
 
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