[Python-ideas] 80 character line width vs. something wider

[Ron Adam]

Greg Ewing wrote:
>> On May 27, 2009, at 14:29 PM, average wrote:
>>> If the medium *emits* light, it's significantly better to have a  
>>> dark background (the reverse being true if the medium is  
>>> reflective--like the surface of a book or Kindle).
> 
> This assertion seems to contradict common sense. All the
> eye detects is patterns of light and dark -- how can it
> know whether the light it receives was emitted by the
> screen itself or reflected by it?
> 
> If there is any such effect, there must be other factors
> involved, such as sharpness or resolution differences
> between the two display surfaces being compared.
> 
> In my experience, dark-on-light tends to look sharper
> than light-on-dark for the same resolution on the same
> medium -- both emissive and reflective -- and it is
> therefore easier to read small-sized text that way.
> 
> I expect that's why Xerox and followers chose black
> on white. It's also probably why we have a long
> tradition of printing black ink on white paper and not
> vice versa. So if Xerox were imitating paper, they
> weren't just doing it blindly, but for a reason.

It seems to me (just speculation) that it was probably easier and cheaper 
to bleach paper white or leave it a light color after making it than it 
would be to dye or color it black.  And also probably easier and cheaper to 
make black ink than to make white ink.  So I think the factors as to why 
books are black letters on white pages is historically economic in nature 
for practical reasons.

I would also speculate that because we are so used to reading black letters 
on a white background, that it would be a bit more natural and easier to 
most people to also do that on computer screens.

The reason may be precisely to imitate paper because that is what most 
people are used to reading ... and it was a selling point.  ;-)

Ron