Auto backlight management?

Benjamin M. Schwartz bmschwar at fas.harvard.edu
Fri Apr 25 01:54:03 EDT 2008


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Jordan Crouse wrote:
| On 24/04/08 22:10 -0700, david at lang.hm wrote:
|> this is the one drawback to the fantasic screen, any light from the
|> backlight that gets through is colored by the screen. it can be made to
|> appear white by allowing all three colors through, but it's still colored.
|>
|> this means that you can't get high resolution mode with the backlight on.
|
| No part of that is true.  The behavior you describe is a myth,
| kept alive by people who misinterpet the display specification.
|
| You can turn on monochrome mode at any time. Try it yourself:
| echo "1" > /sys/devices/platform/dcon/output
|
| Boom - there you go.   Monochrome for your pleasure.

Nope.  Take out your magnifying glass and look: each pixel is either red,
green, or blue, even in monochrome mode. Those are not software-controlled
filters; they're formed by a fixed physical diffraction grating.
Monochrome mode just tells the software to set R=G=B, but with the
backlight on only one of those three is actually displayed at each pixel.

(This may just be a miscommunication, but we might as well be clear.)

One amusing question is: could software potentially set monochrome mode
and then use fancy color-adaptive subpixel rendering to do optimized
display of fonts and images?  Maybe, but at 200 dpi the gains would be
small, and the computational overhead would be huge.

- --Ben
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