Overlay Comparison

Xodo PDF Studio comes with an Overlay Comparison feature that allows you visually compare 2 or more documents by overlaying additional document(s) onto the first using different colors to display any differences. This feature is especially useful for architects and engineers to visually identify even small differences in architectural drawing and blue prints. It can be used not only to compare PDF documents but also scans, images or Word documents that have been converted to PDFs using Xodo PDF Studio.

How to compare two documents using Vector Overlay Comparison

  1. Open the initial or first document in Xodo PDF Studio. This will become Document A (in Green) in the Overlay Comparison.
  2. On the toolbar go to Document Tab > Overlay
  3. This will launch the Create Comparison dialog
  4. Select the documents you wish to compare
  5. Set the options for each of the documents
  6. Click Start and it will create the new overlay document and open it in a separate window

Vector Overlay Options

Below are the options available when setting up the overlay comparison

File List

Add Files - Displays a file chooser to add one or more files to the list

Edit - Opens the layer options for the selected layer

Align Points - Starts the automated alignment tool, see How to Align Documents below

- Removes the selected file(s) from the list.

- Moves the selected file(s) up the list.

- Moves the selected file(s) down the list.

- Moves the selected file(s) to the top of the list.

- Moves the selected file(s) to the bottom of the list.

Layer Options


File - Displays the file name and path of the selected document

Layer Name - Sets the name to be used for the comparison layer

Color - Select the color for the document (the default colors generally provide the best results). See Choosing colors for overlay PDF comparison.

Pages - Set the pages of the document to be compared using the From and To options


Rotate  - Adjust the rotation of the document if needed

Offset X & Y - Adjust the X & Y location values of the document  move it left, right, up, or down

Scale X & Y - Adjust the scale values to increase or decrease the size of the document

How to Align Documents

  1. Add all of the documents you wish to compare to the document list
  2. Click on Align Points to begin the process
  3. Each document in the list will be opened in order. For each document: select the same 3 points, in the same order to align the pages
    • Note: For best results, the points should be far apart (close to the corners)
  4. Once completed the documents will be automatically aligned when the overlay document is created

Once the alignment has been set the Position values in the Layer Options dialog will be disabled. If needed you can click on Clear Alignment to remove the automatically set alingment and set a manual alignment instead.