On 03/11/2015 08:06 AM, scott wrote:
> Plasma screens are possibly the worst for burn-in.

Yeah, so I heard. ;-)

>> I've seen a ghost image burned into the screen on an iMac. Which is
>> weird, because I didn't think LCDs even *do* that! o_O
>
> They will easily burn if the time-average voltage across the pixel is
> not zero volts (they switch between + and - every frame). Obviously
> exactly zero volts is impossible, but the further away from zero you are
> the faster you will burn in that pixel. So it depends on the quality of
> your driver electronics.

Huh. And here I was assuming that Apple would have used only the most 
over-priced hardware components they could source...

...apparently it's only the *best looking* hardware. :-P

>> Now here's a question: Why does printing white text shift the
>> corresponding scanlines left slightly?
>
> On a CRT? I remember that if you drew a white rectangle around the edge
> of the screen, then flipped the inside between black and white and shape
> of the screen would change massively. I believe it's because the extra
> current needed to draw all the "white" slightly reduces the voltage from
> the PSU which is also used to control the timing/geometry, so the shape
> of the picture will change based on the average brightness of the image.

I just remember spending many days (and nights!) in front of a giant 
Grundig CRT driven by my dad's Commodore 64. If you changed the text 
from the default light blue on a dark blue background to being pure 
white, the display got seriously bent.

While we're on the subject, what causes the weird diagonal lines that 
all RF-modulated signals have?

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