Re: [Freetype] New documents available

[Giuliano Pochini]

On 07-Nov-2002 David Turner wrote:
> Hello,
> 
> Giuliano Pochini wrote:
>> On 07-Nov-2002 David Turner wrote:
>> 
>>>Hello,
>>>
>>>   you'll find a new version of the "smooth hinting" document at
>>>   the following address, including screenshots:
>>>
>>>     http://www.freetype.org/hinting/smooth-hinting.html
>> 
>> 
>> Interesting. The screenshots show quite well what has been
>> changed and FT2.1 looks better overall than 2.0. Text brightness
>> is now constant in all characters, which is fine, but the loss
>> of crispness is strange and IMHO can be avoided. Vertical stems
>> are ofter drawn with a "shadow" at their side. Look at one of
>> these chars "hlikdtnLE", the stem is full black, so only a side
>> of it has been grid-aligned. It only happen with vertical stems,
>> while horizontal ones are perfect. Also round parts don't have
>> that the shadow, strange. You can try to enforce better
>> alignment of strictly vertical stems.
>  >
> Alas, this is not so easy. Allow me to quote the web page itself:
> [...]
> 
> You see, strong alignement on the pixel grid is possible, since that's
> what 2.0 did. However, this has the sad "benefit" of making your
> diagonals really look strange, since they often will appear fatter
> or thinner than the horizontal/vertical stems, and this results
> in text that is unpleasant to read and looks *very* unprofessional.
>
> That why 2.1 does things a bit more fuzzy. Because it distorts the
> outline less, it generates text that has "constant brightness", and
> I regard this as a *good* thing. I prefer to optimize the output
> to make the whole text consistent rather than optimizing for only
> 80% of the glyphs, which is unfortunately *very* visible, even to
> un-trained eyes :-)

Yes, I didn't explain my opinion well. What I think is wrong is that
chars with strong vertical stems already looked well with the old
hinter. The new hinter makes them look fuzzier, while it vastly
improves all the other characters which do not have "important" h&v
stems ("wevyscr"). I mean... in some chars most of the "information"
is carried by diagonals and curves, so the user notices immediately
if they are not symmetric (vw), if there is no hole (e) or the
thickness is wrong (ay). Other chars are different: the user expects
that chars like "LIiPBb..." have well defined stems, and a slight
distortion of ther shape is not annoying.
Perhaps the best hinter is something between FT2.0 and FT2.1 :-)) I'm
a coder and I know how much difficult is to solve fuzzy problems
like this. It's not much different than coding a psycoacustic
mode for an audio encoder. Most of the work is: change something
and try again. :)
Ah, what I said is based on the shots you provided. I'll have time
to make some tests in the weekend.

>> Why did you write an hinter for LCD sub-pixels ?  I think that
>> rendering text at triple width works just fine with the default
>> hinter, or am I missing something ?
>>
> First of all, you don't "render at triple width". You hint the outline
> at the *normal* width, and scale the resulting vector horizontally or
> vertically by a factor of 3. This is very different than using a
> triple character width.

Hmm, I haven't an LCD monitor, so I can't try, but I think you have
to scale the outline and *then* apply hinting to get proper alignment
based on the 3x horizontal resolution.


Bye.