Compare documents
Use the Compare Documents feature to compare two PDFs and highlight the differences. The differences are indicated with markups that can be reviewed easily using the Markups list. There is also a batch version of Compare Documents for comparing groups of PDFs.
This feature is similar to Overlay Pages, which converts two or more PDFs to different colors and stacks them one on top of the other to reveal differences. The Overlay function works well for PDFs with vector graphics, while Compare Documents is best suited for working with scanned images or drawings.
To compare documents, see Align PDFs with Overlay Pages in Revu 21.
Advanced comparison options
Use the Advanced Comparison Options to fine tune the document comparison process. Bluebeam recommends that you use the provided Comparison and Rendering settings and change these settings only if the document comparison process doesn't appear to detect differences.
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Revu provides three default comparison configurations: Printed Documents (same printer), Printed Documents (different printer) and Scanned Documents. Each configuration includes preconfigured settings. You can change the settings of any of the default configurations or create a custom Type by selecting <New Custom>.
To permanently change the settings of the current configuration, select Save. In the Save Document Comparison Settings dialog, enter a name for this configuration. If you are changing the settings of a default configuration, you can save it under the default, auto-populated name, or you can change it and create a new configuration.
Revu provides the following Advanced Comparison Options:
Markup Options
- Enter a name for the difference annotations (for example, "Differences 5-7-14") in the Subject field, if desired. Naming annotations lets you easily group the difference annotations on the Markups list by sorting by Subject. You can create a series of difference comparisons over time to provide a change history.
- Set the Color, Fill Color, Opacity and Width to determine the appearance of the markups to be used to annotate differences found during the comparison.
- If cloud markups should be used, select Cloud.
- If the annotations should be locked when you place them, select Locked.
Comparison Options
- The comparison process divides the document into a region of grids for comparison.
- Grid Size defines the size of the individual grid segments used for comparison. These regions are then inspected for different pixels to identify as a differing region.
- Pixel Density controls the threshold for differences in a particular area (defined by the Grid Size) when detecting differences.
- Color Sensitivity helps to determine the threshold at which pixel differences will be determined. A lower sensitivity setting won't detect as many differences as a higher sensitivity setting. This setting works in conjunction with the Pixel Proximity Allowance. Increase this value to check adjoining areas for similar pixels.
- DPI determines the resolution used to rasterize the PDFs. The default setting is 72. Set the value higher (144) if finer resolution is needed for the comparison.
- Set the Margin value to ignore regions around the borders of the PDFs being compared.
- By default, the comparison tool ignores existing markups on the documents, because these can already be easily located via the Markups list. Select Include Markups to override this behavior and render markups for comparison.
- While flattened markups become part of the content layer of a PDF, the comparison tool ignores those that have been flattened as "recoverable" by default. Select Include Flattened Markups to override this behavior.
Page Align Options
- Select Auto-alignment to automatically align the drawings or documents that are being compared. Auto-alignment is recommended for comparing scanned drawings.
- Enter values in the Offset setting if you know one document is offset from the document that is being compared.
To restore the included types to their default settings, select Restore Defaults.
