History & Compare: Undo and Before/After
History and Compare aren’t a tool of their own — they’re two toolbar functions in the editor: edit history via the “Process History” menu, and the before/after comparison as its own toggle.
Undo and redo
| Action | Shortcut (iPad with keyboard) | Condition |
|---|---|---|
| Undo | ⌘Z | active only while history isn’t empty |
| Redo | ⇧⌘Z | active only while something has been undone |
Both live in the “Process History” menu.
How steps get bundled
Every “discrete” change — switching a preset, or creating a mask, for example — creates its own history step. A slider you drag with your finger, on the other hand, would create hundreds of intermediate steps without bundling: so the app collapses one continuous drag — from first touching the control to releasing it — into one history step. An undo therefore reverses the whole drag, not just the last fraction of it.
Save projects and continue editing
The app automatically saves the original, edits and history as a local project. The Process History menu shows the save status and Share Project. If saving fails, you can retry it.
Open Projects on the welcome screen to resume an edit. The project list supports favorites, renaming, sharing and deletion. Swiping left starts deletion with confirmation. Shared project files contain the original and edits; a JPEG export contains the finished image.
Before/after comparison
A toggle switches between “View Original” and “View Edits” (accessibility label: “Compare Before and After”).
When comparison briefly becomes unavailable: while a geometry change is in progress — crop, rotation, or keystone correction — comparison isn’t available. The reason is that the original, preview, and document geometry briefly don’t line up exactly while a change is in progress; comparison would otherwise show a distorted image. Once the geometry change is complete, comparison becomes available again.
Practical tips
- Drag a control to its target value in one continuous motion instead of several short movements — otherwise, each new touch on the control creates its own history step.
- Use before/after comparison regularly between individual tools, not just at the end — it shows you whether individual steps are still adding up the way you intended.
- If comparison is unexpectedly greyed out, check whether a crop, straighten, or keystone change is currently open — it returns automatically once that’s finished.