ASH PDF Studio Help

Compare revisions

Compare revisions shows what changed between two revisions of a document, such as a contractor's Rev.00 and Rev.01 of a drawing. Each page of the newer revision is compared with the same page of the older one, and the result opens as a new PDF in its own tab, with every change marked.

Run a compare

  1. Open the two revisions, or at least one of them. In the app: Help ▸ Show me
  2. Choose Tools ▸ Compare revisions….
  3. Choose the Older revision and the Newer revision. The lists show your open documents; choose Browse… to open another file. When the names carry a revision, such as Rev.00 and Rev.01, R0 and R1, or A and B, the older one is chosen for you.
  4. Optionally set:
    • Pages: leave it empty for all pages, or type pages such as 1-5 or 2, 4, 7.
    • Quality: 100, 150 (the default) or 200 dpi. Higher quality finds finer changes but takes longer and makes a larger result.
    • Align shifted pages automatically: when a whole sheet has moved a little (for example, after it was re-plotted), the pages are lined up before they are compared, so the shift itself is not shown as a change.
    • List text changes: also lists the words that were added and removed.
  5. Click Compare. A progress box shows the page being compared; click Cancel to stop. Nothing is opened when you cancel.

The app stays usable while a compare runs, even on a large sheet at 200 dpi: the pages are compared in the background, so the window keeps responding. Cancel stops the compare at once, also in the middle of a page. If the background compare is not available, Cancel takes effect after the current page.

The comparison is of the ink on the page: a line or word that only changed colour is not counted as a change.

Read the result

On each page of the result:

Each changed area has a dashed rectangle round it with a short note, such as "Change 1: added" or "Change 2: added and removed", plus the words that changed inside it. Point at a rectangle, or open it, to read its note. A legend in the corner names the two revisions, the date of the compare and the page compared (for example, "Page 5 of Rev.01"), and the Bookmarks list each page with changes by that page number.

Pages that cannot be compared

If one page cannot be compared (for example, it cannot be drawn), it is skipped and the compare carries on with the others. In the result that page is blank, with the legend and a note "Page 5 could not be compared" and the reason, and it has a bookmark "Page 5 – not compared". The Differences panel, Copy list and Export CSV list it as "Page 5 – not compared" with the reason. If no page can be compared, no result is opened and a message lists the pages and the first reason. Cancel always stops the compare, with or without such pages.

The Differences panel

The Differences panel opens in the sidebar with the result. It lists each page with changes by its page number in the revisions (with Pages set to 5-7, the first is Page 5; if the older revision's page number differs, it is shown too, as in Page 5 (older 4)), then its areas (Change 1, Change 2, …) and its text changes (+ added, − removed).

Save, print or send the result

The result is an ordinary PDF. Save, print or send it like any other document (see Save and print). It is a new file: the two revisions you compared are not changed.

Limits