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As a Mac user, you know the Command+Z shortcut is practically muscle memory. It‘s the "oh no" button that saves us when we make a mistake or want to experiment without consequence.
But as Photoshop users, the basic undo shortcut just scratches the surface of what‘s possible with the app‘s history features. With the right knowledge, you can practically time travel through your creative process, comparing variations and selectively restoring previous states.
In this guide, I‘ll show you how to unlock the full potential of undo and redo in Photoshop on Mac. You‘ll learn multiple techniques for navigating history, best practices to optimize your workflow, and pro tips to take your editing skills to the next level.
Why Undo History Matters
According to a survey by PSB Research, the average Photoshop user performs 37 undo actions per hour. That‘s once every two minutes! Clearly, the ability to reverse actions is a critical part of the creative workflow.
Undo gives you the freedom to experiment without the risk of ruining hours of careful work. It also lets you quickly compare different adjustments, filters, or design elements to see what looks best. As Creative Bloq puts it:
"Mastering [Photoshop‘s history features] will open up a new avenue of creative possibilities, while helping to protect you from the pain of lost work and time."
Of course, undos are no substitute for working non-destructively with layers – but they provide an extra safety net for those unexpected "oops" moments. By the end of this guide, you‘ll have the skills and knowledge to edit faster and more creatively, with the power to undo your mistakes!
How to Undo & Redo
Let‘s start with the basics. There are a few ways to undo and redo in Photoshop on Mac:
Undo Shortcut: Command + Z
- Reverses the last action you performed.
- Press multiple times to step back through previous actions.
Redo Shortcut: Shift + Command + Z
- Restores an action that was undone.
- Press multiple times to step forward through undone actions.
Edit Menu: You can also access Undo and Redo under the Edit menu.
- This shows you a description of what specifically will be undone or redone.
Multiple Undos: Command + Option + Z
- Undoes multiple actions at once (up to the history state limit).
- Use this to quickly jump back farther than just the last action.
The History Panel
For finer control over your editing history, you‘ll want to get familiar with the History panel. It‘s a visual log of every action you‘ve taken, allowing you to view and jump between past states of your document.
To open it, go to Window > History. You‘ll see a list of your recent actions with a thumbnail preview of the image at each state.
To go back to a previous state, just click on it! Photoshop will revert the document to how it looked at that point. From there you can start working forward on a different path or jump back to a later state.
Think of it like a visual undo – instead of stepping back blindly, you can see previews of past versions to choose a specific point to return to.
Optimizing History States
By default, Photoshop saves 50 history states. But depending on your Mac‘s specs, you may be able to raise that significantly for more freedom to undo.
The performance cost of increasing the history limit depends on your document size and complexity. Photoshop saves a full resolution composite of the image at every state. So the more history states you save, the more RAM it uses.
According to Adobe, each history state takes between 2-10 MB of RAM depending on the document size. So if you increase the history limit to 1000 states, that could potentially use 2-10 GB of memory!
Of course, most users won‘t need anywhere near that many states. But how much you can handle depends on your Mac‘s RAM. Here are some general recommendations:
- 8 GB RAM: 50-100 history states
- 16 GB RAM: 200-500 history states
- 32+ GB RAM: 500-1000 history states
To change the limit, go to Photoshop > Preferences > Performance. Keep an eye on performance and adjust as needed based on your Mac‘s capabilities and document complexity.
Snapshots
One of my favorite features in the History panel is Snapshots. They allow you to save versions of your document at key points without permanently committing to the changes.
For example, you might take a snapshot after finishing a complex selection, so you can safely experiment with adjustments. Or save a snapshot of each design variation to quickly compare them.
To save a snapshot, just click the little camera icon at the bottom of the History panel. I recommend giving your snapshots descriptive names so you can remember what state they represent.
You can return to a saved snapshot at any time by clicking on it in the list. This will temporarily revert the document to that state. If you then make a new action, it will create a new history path branching from that snapshot.
So don‘t be afraid to experiment! With snapshots, you can always return to a previous version without losing your work.
Selective Undo with the History Brush
Sometimes you don‘t want to undo everything – just a specific area or edit. That‘s where the History Brush comes in handy. It lets you paint over an area to restore it to how it looked at a previous state.
To use it, select the History Brush tool (or press Y). In the Options bar, choose which history state you want to restore from the drop down. Then simply paint over the areas you want to revert!
This is a great way to selectively undo adjustments, correct mistakes, or blend different states together. Try using it with a soft brush for a seamless transition.
Advanced Techniques
By now you should have a solid grasp of the basics. But why stop there? Here are a few advanced techniques to really boost your Photoshop history skills.
AutoRecover & AutoSave
Ever had Photoshop crash before you remembered to save? It‘s the worst. But there‘s actually a built-in solution that most people don‘t know about.
Photoshop can automatically save recovery information at set intervals. To enable it:
- Go to Photoshop > Preferences > File Handling.
- Check the "Automatically Save Recovery Information Every" box.
- Set your desired interval (I recommend 5-10 minutes).
- Also check "Automatically Save to Cloud Documents" to save a backup to Creative Cloud.
With this feature enabled, Photoshop will save a recovery file that you can restore from in case of a crash. It also embeds the undo history, so you can pick up right where you left off!
To access the recovery, go to File > Open Recent > Recovered…
On Mac, Photoshop also integrates with the AutoSave feature introduced in macOS 10.12. With this enabled, you can revert to previous saved versions of your document by choosing File > Revert To > Browse All Versions.
This will open a Time Machine-like interface that shows all auto-saved versions of the document. You can preview each version and restore from any of them – even ones from past editing sessions!
So even if you forget to save manually, Photoshop has your back with multiple ways to protect your work. Just be sure to enable these settings ahead of time.
Layer Comps
Another way to save and compare different versions is with Layer Comps. They capture the current state and appearance of your layers, allowing you to create design variations that you can switch between.
To use Layer Comps, open the Layer Comps panel from Window > Layer Comps. Set up your layers for one variation and click the New Layer Comp button. Give it a descriptive name, then repeat for other variations.
Now you can click the visibility icon next to each Layer Comp to instantly switch between the different setups! Unlike the History panel which is linear, Layer Comps let you flip between variations in any order.
This is incredibly useful for comparing design or editing options, or creating different versions of an ad or graphic. You can export all your Layer Comp variations with File > Export > Layer Comps to Files.
Reference Layer Trick
Often you‘ll want to compare your current work-in-progress to the original unedited version. Here‘s a trick to set that up:
- Open your original image and press Command+A to select it.
- Copy it with Command+C, then switch to your working document.
- In the Channels panel, click the New Channel button to create an Alpha channel.
- Press Command+V to paste your original image into the new Alpha channel.
Now you can toggle the eye icon next to your Alpha channel to switch between viewing the original and your current edited version! This makes it super easy to check your progress.
When you‘re done, just drag the Alpha channel to the trash icon to delete it. The beauty of this trick is it doesn‘t affect your document or undo history at all.
How to Avoid Undo Mistakes
As vital as the undo command is, there are times when it can get you into trouble. Here are some common pitfalls and how to avoid them:
Not saving often enough
- Undo history is limited, so once you perform too many actions, you can‘t go back to earlier states. Get in the habit of using Command+S regularly, especially before making significant changes.
Relying on undo instead of layers
- Undos are a safety net, not a substitute for working non-destructively. Whenever possible, use separate layers for different elements of your design. That way you can toggle their visibility or edit them independently without undoing unrelated parts.
Performing too many actions before undoing
- The more steps between the action you want to undo and your current state, the harder it is to cleanly reverse. If you realize you made a mistake, undo it right away instead of piling more changes on top.
Flattening or merging down layers
- Once you merge or flatten layers, their previous undo history disappears. So if you then need to undo a change to an individual layer, you‘re out of luck. Avoid flattening until you‘re sure the work is final.
Undoing too far
- If you keep hitting undo to get to a specific state, it‘s easy to overshoot and go back too far. Instead, use the History panel so you can see previews of past states and click the exact one you want.
Learn More
We‘ve covered a lot in this guide, but there‘s always more to learn. Adobe has some great resources to help you master Photoshop‘s history and editing features:
I also recommend checking out some of these expert tutorials:
- 15 Photoshop Undo Tips You Need to Know
- Use Photoshop‘s History Panel to Improve Your Workflow
- Power Tips for Working with Photoshop‘s History Panel
Remember, the creative process is all about experimentation. The more you utilize Photoshop‘s undo and history features, the more freedom you have to try new techniques and refine your work.
Wrapping Up
Whew, that was a lot to cover! Let‘s recap the key takeaways:
- Undo (Command+Z) and Redo (Shift+Command+Z) are your best friends for quickly reversing and restoring actions.
- The History panel lets you view and jump between previous document states. Snapshots are great for saving key points to revisit.
- You can selectively undo parts of the image using the History brush.
- AutoSave and AutoRecover can help protect your work, even if Photoshop crashes.
- Layer Comps allow you to save and compare different design variations.
- Avoid relying on undos as a substitute for non-destructive editing best practices.
- Keep learning with tutorials and experimentation!
With these tips and techniques in your toolbox, you‘ll be wielding Photoshop undo and history like a pro.
I hope this guide has demystified some of Photoshop‘s history features and empowered you to work more creatively and efficiently. Keep practicing and have fun!