Product

Kodak^® Prinergy^® (all versions)

Symptoms

The counters or center holes in some fonts fill in when proofed or output to plate at high resolution or when viewed under high magnification zoom in the Adobe^® Acrobat^® software.

Background: In a Prinergy workflow, you expect that proofs should match plates, however, there are certain rare cases where they do not match. Some badly built fonts can have the low-resolution output show glyphs with compound paths (for example, the center of an O) open, but the high-resolution data for the font has the character or font glyph filled in. In these cases, font hint rules (low resolution) do not match the corresponding PostScript^® (high resolution) for the problematic fonts.

Cause

There are three possible causes:

Cause 1: When you view low-resolution output at high magnification, the font hinting is not able to display the font accurately.
On low-resolution output and at low magnification, the font rendering uses font hinting rules to display the glyphs. Acrobat, Kodak Prinergy Separation Viewer software, and Adobe RIPs all display fonts differently at low resolution/zoom than at high resolution/zoom. This is because at low resolution/zoom, the font hints are used to render the font, but at high resolution/zoom the real font vector data is used. (See Solution 1.)

Cause 2: In some cases, the Kodak code that converts text to paths doesn't work because the outlines follow the same directions as the paths in the font.
For example, some font glyphs violate the non-zero winding rule (the paths drawn to describe the glyph go in the same direction, yielding a filled in counter). The paths should follow the even-odd winding rule (inside paths go in the opposite direction to the outside paths) so that the internal area can be drawn and filled properly. Note that this fill operator describes all objects with inside and outside paths (not just fonts). (See Solution 2.)

Cause 3: Entire font glyphs drop out.
Some fonts contain hint information which can exceed a set PostScript interpretation limit and cause glyphs to fill in or in some cases drop out entirely. (See Solution 3.)

Solution

Solution 1: The workaround is to convert text to outlines when rendering a page or imposition to high resolution. However, if you receive this kind of job often, you should contact the font manufacturer and ask to have the font fixed.

Solution 2: Modify the font with a font editing program (for example, Fontographer) or ask the font manufacturer to fix the font.

Solution 3: Render with font outlining turned on (note that text can appear fat on low-resolution output). When you outline or vectorize text, you lose the hinting function that allows text to render well to low resolutions (such as on-screen) or at small sizes. This is similar to the problem that occurs if you convert fonts to outlines in the Adobe Illustrator^® software (it looks fatter). Normally, the loss of hinting is only a problem at low resolutions.

Keywords

Acrobat, font, output, plates, proofing

Technical contact(s)

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Date submitted

08 Jan 2008