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Undo History - Why limit it?

First off, this seemed like the best spot as Undo is a de facto user interface requirement for any editing program.

For school we use Photoshop CS3 and it seems it can only go back roughly 25 steps.

However, is there a valid User Experience reason why Adobe don't allow the ability to have infinite undo? Many other popular applications do offer infinite (or near infinite) undo such as:

  • Chrome (infinite <Back>)

  • Paint.NET (infinite undo)

  • Windows/File Explorer (infinite <Back> as far as I can tell)

  • MS Word (infinite undo)

The closest you can get to this in Photoshop is duplicating the layer you are going to modify and hide one of them.


3 Answers 3


A quick search of the Adobe site shows the reasoning for this - albeit for CS5 but I would imagine the reasoning is still the same. (emphasis mine):

By default, the Photoshop History panel retains only the last 20 actions. This is a compromise, striking a balance between flexibility and performance. You can change the number of levels in the History panel by choosing Edit > Preferences > Performance (Windows) or Photoshop > Preferences > Performance (Mac OS) and entering a different value for History States.

As suggested in answers here, it's because the more history is stored the greater impact on performance. It is doubtful the target audience of PS would want to reverse more than 20 steps - they provide the Snapshot option to quickly jump to a pre-defined point in history should you wish to experiment with an image rather than carry on as normal. Performance, especially in professional tools, is more important than offering a feature the majority don't need, particularly if that feature can be enabled by the user should they choose.

  • interesting statement though shocking that the option to change it is not more obvious. Frequently workstations will have much more capability than is used in professional settings. 16 - 32 gb ram, quad core etc. Nov 26, 2012 at 23:43
  • True, but Adobe don't know the exact spec of any machine that PS will be installed on, nor do they know the complexity of the tasks it will be used for (which would also have an impact on the stored history) so that's why they compromise and offer a default that can be changed - if you can find out how ;)
    – JonW
    Nov 26, 2012 at 23:46
  • Actually they do, it's information that is available for all programs. Secondly to say they are not capable of knowing how the average user uses their program is an egregious underestimation of the size of Adobe. The only reason left why I might suspect is it's an artifact of a prior age, caused by continuous developer oversight. I personally do not see this as a valid reason why Cole should impose arbitrary limitations simply because adobe does. Nov 26, 2012 at 23:54
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    The only problem with Adobe I see is lazyness of the programmers, actually. There is absolutely no reason to have a limited undo, except one: we're too lazy to figure out how to make it infinite and fast. Nov 27, 2012 at 6:33
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    @JonW The problem here is that you HAVE to know how long Undo you need BEFORE actually doing something. It's about priorities, right? I think this feature is more important and that one not, so I will make it configurable or whatever and figure out what to say if someone will ask me about. Nov 27, 2012 at 8:11

Part of the decision is the amount of memory used per undo. In a large, complex application such as Photoshop, there is a large amount of state that is restored in an Undo operation. In a web browser such as Chrome, on the other hand, the only state required is the address, and in some cases form data; this state is maintained anyway (browser history), so it makes sense to make it available.

  • Then explain Paint.net? It saves into a giant cache file that is cleared after file close
    – Cole Tobin
    Nov 26, 2012 at 23:17
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    Yeah I'm not seeing performance being a big deal here seeing as many other much more computationally complicated programs offer unlimited undo (ex: Solidworks). Nov 26, 2012 at 23:46

The only rationale is performance, however it's best to determine by asking the users what kind of computers they use, and how they use the software to determine how far back you should make the history go. I'd suspect for most modern computers there's no reason why you should not use unlimited undo, with exception of maybe Video editing. In programming we often have not only unlimited undo but also branching and merging of history.

If you can include that in an art program you're my hero forever.

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