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[css3-fonts] comments on synthetic italics in vertical text from Tara Yamamoto

From: John Daggett <jdaggett@mozilla.com>
Date: Mon, 13 May 2013 23:35:44 -0700 (PDT)
To: www-style list <www-style@w3.org>
Message-ID: <621775001.15195267.1368513344939.JavaMail.root@mozilla.com>

I sent mails to several members of Adobe's Japanese text layout team
regarding the use of synthetic italics in Japanese and the use of
obliquing (斜体 shatai) in Japanese layout.  Taro Yamamoto responded
with the messages below and other members of the layout team concurred
with his comments. Both are quite detailed and I got his okay to
forward these very insightful comments.

Message from Taro Yamamoto:
  
  Before explaining it, I think it is necessary to say that Western
  obliquing/slanting is different from italicizing also. Italicizing
  implies that an italic font belonging to the same typeface family and
  sharing the same weight and width properties as those of the original
  roman font is searched and used. For example, if you "italicize" a
  character in "Univers 55", the font should be replaced with "Univers
  56" (Univers Regular Italic) instead. If you use "Adobe Garamond Pro
  Regular", it is expected that italicizing it will change the font to
  "Adobe Garamond Pro Italic".
  
  Furthermore, there are cases where the original roman font does not
  have any accompanying "Italic" font. If so, it is the responsibility
  of the typographer to correctly specify which font should be used,
  when italicized glyphs are needed. (Because of this, automatically
  applying the "slanting" effect to upright roman glyphs, for whatever
  reasons, can be a latent seed of serious problems, which tend to be
  difficult to detect. So, I personally don't like the method).
  
  If no corresponding "italic" font is found on the system, without any
  explicit alternative italic font specification, it's up to the
  strategy of the system, whether to automatically transform and use
  artificially "slanted" glyph shapes crafted from the original roman
  font, or simply regard it as an error.
  
  People may assume that this "slanting" operation is always related to
  the original "italicizing" specification. But, it is not. The two can
  be related, only when the automatic "slanting" is acceptable as a
  solution to the missing of the true italic glyphs.
  
  Now, we have reached the starting point of the discussion about
  "Shatai" and "Slanting" (I decided to capitalize the first characters
  of the two words from now on).
  
  First, I think we need to understand what slanting in this context
  means. As far as I know, it can be defined as a shearing
  transformation whose origin lies somewhere on the left-side of the
  type body in the horizontal writing mode (x = 0, in the character
  coordinate of each glyph), with or without an offset in y (the offset
  may be adjustable for better vertical alignment to the type area, but
  may be simply zero). Here I assume the roman baseline is at y = 0, but
  it is not necessarily so, but it is fine, as far as the origin of the
  shearing is decided relative to the roman baseline position.
  
  I tried to explain what the automatic slanting meant. From this, I
  think we can see that it has nothing to do with ordinary Japanese type
  bodies that tend to be EM squares, and each of whose glyphs is
  centered within the square body.
  
  On the other hand, Shatai is a compression transformation that can be
  applied in different possible angles and with different factors to
  each EM body with respect to the center point of the EM box, and if
  the baseline-alignment option is set, the affected glyphs are rotated,
  so that the direction of the progression of the upper and bottom (or
  left and right) sides of the type body matches that of the line.
  
  Does the Shatai operation have anything to do with Western roman
  glyphs and its dimensional properties? It doesn't. The difference
  between Shatai and Slanting is a fundamental difference, and the
  difference is not only in the appearance of the results from the two
  operations, but in its underlying operational model. This means that
  the two things are totally different things.
  
  If I summarize these considerations:
  1. It is nonsense to apply "italicizing" to Japanese characters and lines.
  2. It is nonsense to apply Slanting to Japanese characters and lines.
  3. It is nonsense to confuse "italicizing" and Slanting.
  4. It is nonsense to apply Shatai to Latin alphabet characters and lines.
  5. Although some people may feel strange, seeing a typical Japanese
  vertical line with Shatai, because the left side of each type body is
  positioned lower than the right side, this is very reasonable
  according to the tradition of Shatai transformation in Japanese
  typesetting. (By explicitly adjusting the Shatai transformation
  parameters, it is not impossible to make the right side down, and the
  left side upper, but it is unusual).
  
  Still, yet, all these things do not contradict that there are cases
  where one can apply some external geometric shearing operations
  completely independently and separately to a line of text, if a
  graphic tool for the purpose is available, having nothing to do with
  the abovementioned glyph-level operations such as Italicizing,
  Slanting and Shatai.
  
Additional message from Taro Yamamoto:

  To say simply, the word "shatai" in Japanese had its concrete,
  distinct semantics in the days of Japanese manual photo-typesetting
  machines. It could be combined with "cho-tai" (condensed), "heitai"
  (expanded) and "shatai-line-zoroe" (to align the direction of a side
  of the slanted glyph to the parent line direction). However, it is
  important to see that these "operations" are only for "special
  effects", and in most cases, these were used only for big display
  lines (for supermarkets fliers).
  
  On the other hand, except the earliest days of italic types, the
  convention of using italics as a secondary type style has been widely
  accepted in Europe and the U. S.
  
  In Japan, sha-tai has not been used widely in long texts and books.
  So, no one needed to consider how to adjust the spaces before and
  after a sha-tai area. So, no rules or standards have been established.
  It's just a special effect.
  
  I don't mean that a "shearing" operation for text is always
  unnecessary in Japanese. If necessary, you can make one (as
  phototypesetting machine users did it in the past). If necessary,
  please define it separately.
  
  Still, I believe that the italicizing and slanting operations that
  work for Western language texts cannot work directly for Japanese
  characters and glyphs, and should not be simply applied to Japanese.
  This not so simple an issue.
  
Received on Tuesday, 14 May 2013 06:36:16 UTC

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