Find Differences in Any Two Documents

August 19, 2004 - 2:00am ||| 0 Comments | Add new

Have you ever been in a situation where you needed to figure out what was different, if anything, between two look-alike documents? Maybe you've got two differently-named files that look the same; but you want to make sure they're exactly the same before you toss one. Or you need to check that copy edits were made, and nothing else, between the "almost final" version of a page layout file sitting on your hard drive and the "final" version your freelancer just delivered.

If you're dealing with long documents, this task can be onerous. Even comparing a couple short ones — line by line, break by break — can be a pain.

There are a number of software programs available that can automate the task: They compare two documents and report on the differences between the two. Unfortunately most of them are file type-specific. Adobe FrameMaker can compare two FrameMaker documents, but no other kind. Ditto for Microsoft Word.

Barebones Software's BBEdit can compare two plain text files generated in any program, but how often do you need to compare plain text files? (Wait, I take that back. I use BBEdit to help me find tiny coding differences in two versions of the same .html file — "why is pageA.html working and pageA1.html not working when all that's different is a .gif? Why, Lord, why?")

BBEdit (Mac only)

Most often, though, designers need to isolate the differences between two versions of a client project done in Adobe InDesign, PageMaker or QuarkXPress. None of those programs has a "compare" feature.

Acrobat 6 to the Rescue

Armed with Acrobat Pro v6.X, you can do an end run around the problem and compare those layout files. Or any kinds of files that can be exported to PDF, for that matter.

1. Export the two files you want to compare to PDF format, using the same PDF settings for each.

2. In Acrobat Pro v6 (Acrobat Standard doesn't have this feature), choose Document -> Compare.

3. In the Compare dialog box, use the two Browse buttons to select the two PDFs you want to compare. If you have them open already in Acrobat, they'll appear as choices in the dropdown menus next to the Browse buttons.

4. Choose a Compare method: Page-by-Page Visual Differences will highlight (with Acrobat's advanced commenting tools) differences in image, color, and text; Textual Differences also uses the commenting tools to highlight differences, but focuses on the copy alone and gives you more details (e.g., which words were inserted/deleted).
If you choose the Textual Differences method you have the option of also comparing text formatting ('was this word bold before?"). To wring the most out of Acrobat you may need to run the Compare twice, once for each method.

5. Choose a Report Type: Side-by-Side Report creates a new, temporary PDF document with the two documents in side-by-side format, each with differences highlighted (best for Textual Differences). Consolidated Report adds markups to just one of the PDFs, showing where it's different than the other.

6. Click the Compare button to run the Compare and generate an on-screen Report.

All the markup is done via Acrobat's commenting tools, so all you need to do is look for the comment icons and hover your mouse over them to see details, which are scanty. You might want to open the Comments tab to quickly navigate from comment to comment. You can print out the report for reference, but since comments don't print by default, be sure to choose "Documents and Comments" in the Print dialog's "Print What" dropdown menu.

Now you just need to go back to the page layout files and figure out what to do about the differences.

Not the Complete Solution


I have to tell you, though, that as neat as this feature is, it's not perfect.

First, the Visual Differences report will highlight things that are different but won't tell you exactly what's different about them. For example, if an image has been scaled a tiny bit or has a different-colored border or stroke, Acrobat will highlight the entire image. That's it. You have to go back to the page layout document and figure out what's different.

Second, as far as I can tell, it doesn't highlight differences in the content of images or color models, such as detecting if one .eps graphic is filled with a Pantone color and its twin in the other document is filled with a CMYK color. (You can use Acrobat's Separations Preview palette to check for that particular situation, though.)

Yes, I consulted the manual <g>. It offers precious little detail on exactly what it can and cannot compare or detect. Perhaps there's a third-party book out there on Acrobat 6 that goes into the feature in depth; unfortunately I don't own it. If you know of one, email me.

Nonetheless, Acrobat's Document Compare feature has saved my bacon more than once; just by virtue of helping to isolate the three or four areas in two versions of a huge document that differ. And for detecting straight text differences, it works like a charm. Best of all, I don't have to buy or install anything to use it!

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