TIFFs exported from PowerPoint won't open in other applications

Problem

You save a TIFF version of your slide or slides from PowerPoint XP directly or use the PPTools Image Exporter to export TIFF files from PowerPoint XP.

You can't open the resulting files in Photoshop (it gives an error message like "Problem parsing the TIFF file"). The problem is seemingly random. Sometimes the files are fine, sometimes not.

Solution

There are several workarounds to the problem:

• Another application may be able to open the problem TIFFs. If so, open and resave each file (possibly to another format like PNG) then try opening the results in the original application that couldn't open PPT's exported TIFFs.
• Save TIFFs from an earlier version of PowerPoint if one is available. As a rule, text in the exported files will look better, too.
• Export PNGs from PowerPoint instead of TIFF. Most modern applications that accept TIFF will also open PNG files. There's no quality penalty in converting between the two formats. There are programs like the superb (and free) IrfanView that will batch convert the files for you.

PowerPoint 2000 and PowerPoint 97 don't have this problem. We're not certain whether PowerPoint 2003 does or not.

Background

For the technically curious, here's some more information sent us by a customer (to whom I apologize for having forgotten his name!)

The problem is in the TIFF file's Resolution Unit field. The specs have this to say:

ResolutionUnit
Tag = 296 (128 hex)
Type = Short (16-bit word)
N = 1
Values can be:  1, 2, 3
Default = 2 (inches)  Ie, resolution units are in inches, not meters or lightyears or ....

In a corrupted TIFF file, you might find a sequence like this:

28 01   03 00   01 00   00 00   02 C0   00 00

where (remember that byte order is reversed on a PC)

28 01 = ResolutionUnit tag = 128 hex
03 00 = Type Short
01 00   00 00 = Count
02 C0 00 00 = Value

02 C0 should be 02 00 (2 rather than 00C0 hex or 192 decimal)
PowerPoint may put other random bytes into this same slot. If they're 127 (7F hex) or less, Photoshop will open the file, it seems. If the value is 128 (80 hex) or higher, Photoshop won't eat it.

If you edit the file and change the random byte to 00, it opens in Photoshop.

Of course, without a detailed knowledge of the TIFF file format, finding the byte in order to change it is a bit tricky. We're not suggesting this as a general Mr. Fixit strategy.

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