PUB3: Publisher Can't Import CMYK TIFF Images

Q136291

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The information in this article applies to:

 - Microsoft Publisher for Windows 95, version 3.0
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SYMPTOMS
========

In Publisher 3.0, if you attempt to import a CMYK TIFF file, you may
receive the following error message:

   Publisher cannot convert this picture.

   This is either because Publisher doesn't recognize the format of
   the picture you want to add or there was an error loading a
   graphic converter. Publisher has graphic converters that enable it
   to recognize most picture formats. Some of these converters may
   be missing. To install converters for word processors and graphics,
   run Publisher Setup again.

Reinstalling the filters does not resolve this problem.

CAUSE
=====

While the TIFF graphic filter that ships with Publisher version 3.0 and
Microsoft Office version 7.0 can import some CMYK TIFF images, if this filter
fails to import a CMYK TIFF, you receive either a general protection (GP) fault
or your machine stops responding (hangs).

To prevent potential data loss, Publisher checks a field in the TIFF header
called PhotometricInterpretation. If this field is equal to 5 (color-
separated TIFF), Publisher does not attempt to import the graphic and returns
the error message instead.

RESOLUTION
==========

Upgrade to Microsoft Publisher 97 which includes a TIFF version 6 graphic
import filter.

MORE INFORMATION
================

A CMYK TIFF file is a TIFF file that defines the color of each pixel using
cyan, magenta, yellow, and black channels instead of red, green, and blue
channels. Because each color channel requires eight bits of data, a CMYK
TIFF requires 32 bits to describe each pixel.

NOTE: Because you can define the same color several different ways using
CMYK, you actually still only have the same number of colors available as
you do if you use 24-bit RGB values to define your colors. For example, a
middle gray that is defined as (127,127,127) using RGB values can be
defined as (127,127,127,0) or (0,0,0,127) using CMYK values. Therefore,
CMYK images are still classified as 24-bit color images, even though they
actually use a 32-bit color definition scheme.

CMYK TIFF images may also be device-dependent. The "TIFF 6.0 Specification"
recommends against using this type of image as general clip art:

   Since separated images are quite device-specific and are restricted
   to color prepress use, they should not be used for general image
   data interchange. Separated images are to be used only for prepress
   applications in which imagesetter, paper, ink and printing press
   characteristics are known by the creator of the separated image.*

REFERENCES
==========

Aldus Developers Desk, "TIFF 6.0 Specification," page 66

Additional query words: 3.00 w_mspub mspub .tif Tagged Image file format
TIFIMP32.FLT