File / Save Missing From Lightroom?
So you've been working on an image in the Develop module of Adobe Lightroom and you you're ready to save your changes. The problem is, there's no "Save" or "Save As..." option on the File menu. How can that be?
In most image editing programs, if you don't save your changes, they will be lost when you exit the application. Typically when exiting, you will be prompted to save your changes to prevent this from happening, but if you ignore this warning, your image will revert to what it was the last time it was saved. This behavior is not exclusive to Adobe Photoshop and other programs that edit images either, it is common to virtually all programs that edit documents, regardless of type. I'm currently writing this in Microsoft Word, and if I don't save my changes I'll lose them when I close Word. Given all this then, it comes as a surprise to new users of Adobe Lightroom that the program neither prompts you about saving changes when you exit nor even provides menu commands to do so without exiting.
But when you re-open Lightroom and return to an image you worked on previously, your changes are still there, just as you left them. It's as if you never closed the program in the first place. The truth is, Lightroom automatically saves all your changes without ever asking. When you first realize it works this way, you might get somewhat concerned. It seems an odd feature for Adobe to build into the product. Optimizing image is somewhat of a trial and error proposition and it is not at all uncommon to change your mind about a particular tweak. If Lightroom saves every change you make without asking, what happens if you change your mind?
The answer to this conundrum lies in the way Lightroom handles edits. Rather than directly manipulating the content of open files as do most programs including Adobe Photoshop, Microsoft Word and just about everything in between, Adobe Lightroom is a completely nondestructive editor. All changes you make while optimizing an image are saved simply as an instruction list to be applied to that image dynamically. Each step of the process can be viewed in the History panel. Even after you close the program and later re-open it, the history for each image is still there.
The capabilities of the History palette don't end there either. If you move your mouse over the steps in the History panel without actually clicking on them, you will be able to see what your image looked like at each step in the Navigator panel thumbnail above the History panel. To see the main image as it was back then, click on a History step. Your actual image won't be affected since everything is non-destructive. Clicking just changes what you see, not the underlying image data. You can easily go back and change your mind too. If a History step is selected, new changes will be added at that point and all previous steps that came later will be gone, just as if they had never happened. And don't worry if you do this by accident. If you inadvertently revert your image to a prior state by having a prior step active when performing a new edit, a simple press of Control-Z (Undo) will remove that new step and your previous history that had vanished will be right back where it should be.
If you right mouse click on a History step, you'll see even more capabilities. "Create Snapshot" will add an entry to the Snapshot panel for your image as it looked at that step. You will be prompted for a snapshot name but you should give each snapshot you create a meaningful name to make keeping track of things easier. Creating a snapshot doesn't really make a copy of an image either so you needn't worry about using up a lot of space. Snapshots are really just copies of the history list up to a given point that let you get back to a prior image state easily.
The "Copy History Step Settings to Before" right-click option has to do with Lightroom's ability to compare images. If you select View >> Before / After you can change the main image view to a split screen, either vertically (Left/Right split) or horizontally (Top/Bottom split). Once you do, you can use the "Copy History Step Settings to Before" right-click to modify the left (or top) portion while the right (or bottom) portion of the image reflects the History active step. Lightroom's comparison capabilities are quite powerful once you get the hang of how it works. You can change each side of the comparison window independently. Right click on a step and choose "Copy History Step Settings to Before" to control the Before side, or single click (normal left mouse click) on a step to control the After side. You can also compare saved Snapshots just as easily in exactly the same way.
If you're a longtime Photoshop user, this whole nondestructive editing thing will probably take some getting used to. In many ways, Lightroom is like combing the organizing power of Adobe Bridge with the image optimizing features of Adobe Camera Raw, but that really only begins to scratch the surface of what Lightroom is all about.