Does a web site with mostly black pixels in the background really use less energy than white pixels?

Question

Web sites like Blackle.com and Earthle.com claim that black pixels use less energy than white pixels. But does the science really back this up? It still takes energy to create a black pixel. A black screen is not really the same as a blank screen (turned off, for example).

Answer 1

A black screen may not be exactly the same as a blank screen, but it is much closer than a white screen.  Black pixels are not nearly as bright as white pixels, so they do not take nearly as much energy to show up.  When you consider that there are thousands of pixels on a single monitor and that millions of people may be viewing a webpage, a black background could save tons of energy.  Yes, it's better.

Answer 2

it is the same idea as using the light bulb, 40 wz uses less energy than 60 wz, and it gives off a weaker light

so black pixels use less energy than white ones

Answer 3

Not sure about the blackle.com and earthle.com claims but I would say it depend mostly on the monitor type. If its a CRT based monitor then it will draw more power than a LCD monitor. In general all CRT monitors have 3 cathode ray guns - one for Red, Blue and Green. The combination of the three colors generates the other colors. To produce black all these guns are turned off, hence reducing the amount of power consumed. But in the case of LCD monitors, color is generated by the different orientation of the liquid crystals. If polarized light is passed through the oriented crystals, different colors are produced. Not sure about how black color is produced in LCD monitors.

Answer 4

Not if you print it!

Answer 5

They do not.  The same amount of output is emitted when using black pixels.  This is just a fancy way for these websites to say that they are lazy and/or poor website designers.

Answer 6

Interesting question that got me thinking so I did a bit of research and apparently it's true.

A black screen requires 59 Watts a white screen requires 74 Watts, roughly a quarter more power needed for a white screen.

Although black and white pixels are both produced by light the intensity of white is greater than black so requires more power.

Thanks for the question, I've learned something new.