A screen capture of a text like "Mac display uses more colors" which apparently on windows shows just 2 colors ( Black and White ), shows nearly 240 unique colors on Mac. Both images have been saved as BMPs.
Can anyone please explain why there is such a huge difference and how to capture or read in such a way that I get just 2 colors instead of 240 different colors (different shades of grey, black)?
On
To be clear, the much greater range of colours is due to sub-pixel antialiasing being used on the Mac, and presumably turned off (or otherwise not showing in the screendump) on Windows.
SPAA takes advantage of knowledge that each pixel on an LCD is actually three sub-pixels which are controlled independently. So even though a whole pixel width might be coloured in the screen capture, when displayed only a third (or perhaps two-thirds) of the pixel is lit.
Much more info is available on wikipedia, as per usual!
http://en.wikipedia.org/wiki/Subpixel_rendering
It's antialiasing, and Windows does it too, if ClearType is turned on.