How does kerning work?

[Peter Olcott]

Kerning can adjust the between character spacing. It does this by moving
characters closer together based on a kerning table of character pairs. Here is
the key aspect of my question: Does it move characters together by exactly the
kerning amount, or does the kerning amount form the basis for a range of
possible adjustments?

 

[Grzegorz Wróbel]

Kerning can adjust the between character spacing. It does this by moving
characters closer together based on a kerning table of character pairs. Here is
the key aspect of my question: Does it move characters together by exactly the
kerning amount, or does the kerning amount form the basis for a range of
possible adjustments?

I would say it moves exactly the kerning amount, but take into account that what you see on the screen is approximation of printed version. Since resolution of a screen is much lower than printing resolution the font position will be rounded to nearest pixel which should explain your "fff" issue mentioned in another post. That's simply the (in)famous WYSIWYG.

 

[LC Killingbeck]

Kerning can adjust the between character spacing. It does this by
moving characters closer together based on a kerning table of
character pairs. Here is the key aspect of my question: Does it move
characters together by exactly the kerning amount, or does the kerning
amount form the basis for a range of possible adjustments?

You are having trouble accepting that rounding is inevitable, and will
move characters slightly left or right from an "ideal infinite
resolution" position. Assume that the kerning units are 1440 per inch.
[That's from a long ago vague memory, likely from 72 points per inch
and a further subdivision of 20 per point. Might well be wrong, but the
idea is the same.] Suppose your printer does 600 dots per inch. Then
one printer dot is 1440/600=2.4 kerning units. Ergo, rounding is going
to move the printed position of most characters slightly left or right.
Or, assume the screen resolution is 640 pixels horizontally, at a
nominal 80 character traditional fixed-pitch font. That's only 8
pixels per character. Put in a kerning unit of something like 5, and
there will be some rounding, moving the character on the screen left or
right. Or, customize the kerning for 640x480 so there is never ever any
rounding - and watch it fail to be exact in a 800x600 or 1024x768 or
1600x1200 mode.

Welcome to the real world!

Lynn Killingbeck

P.S. Kaaava is a real word with 3 consecutive a's. Finding a real word
with 3 consecutive f's is very difficult - verrry, verrry diffficult!

 

[Character]

P.S. Kaaava is a real word with 3 consecutive a's. Finding a real word
with 3 consecutive f's is very difficult - verrry, verrry diffficult!

That may be, but fff is the notation for forte fortissimo, and is widely used.
Even, rarely, in text with the same meaning.

 

[LC Killingbeck]

That may be, but fff is the notation for forte fortissimo, and is
widely used. Even, rarely, in text with the same meaning.

Putting fff into google.com gets 2,430,000 matches! Not so unusual,
after all! I did not care to run down upper vesus lower case.

Lynn K.

 

[TC]

You're assuming there is just one answer: Yes, or No.

But the answer might be product-dependent!

Eg. product #1's text-rendering engine /obeys/ truetype hints, but
product #2's text-rendering engine /doesn't/.

I already gave you a clear example which showed, unquestionably, that
the same text can be rendered differently by different products:

http://acharya.iitm.ac.in/multi_sys/render/render.html

Unfortunately, ignoring these complexities, will not make them go away!

HTH,
TC

 

[TC]

You're assuming there is just one answer: Yes, or No.

Um, I meant just one answer: (a) the kerning amount /is/ fixed, or (b)
the kerning amount /is not/ fixed.

The rest of what I said, still applies. You're missing the third answer
(c) : it depends on the product & can be different for different
products.

HTH,
TC