Join Jan Kabili for an in-depth discussion in this video Using the Select All command, part of Photoshop CS4: Selections in Depth.
In the Select menu, the very first command is All. The Select All command is used to create a selection around the entire document canvas. There are a couple of situations where Select All will come in handy for you. I would like to show you those in this movie. I'm going to exit out of this menu to tell you about the first situation and that is when you want to copy all of the visible content of a layer. So in this case, I have a file that has two layers. Down in the Layers panel, I'm going to hold down the Option key or the Alt key on a PC and click the eye icon to the left of the landscape layer so you can see that layer contains just this landscape with some transparent pixels that let you see down to the content of the layer below.
I'll Option-click or Alt-click the Sky layer so you can see what's on that layer and that is the sky with clouds. I really like this image and I would like to use it as a background for another composite image that I'm building in another file. So what I want to do is to copy the entire content of the Sky layer and I'm going to use the Select All command to do just that. First, I'm going to turn the landscape layer back on by clicking in its visibility field, and next, I'm going to make a selection around the entire document canvas. To do that, I'll go up to the Select menu and I'll choose All or I could use the shortcut, Command+A on a Mac or Ctrl+A on a PC.
That creates the marching ants around the entire canvas. Now, I'm going to select the layer that I want to copy, which is the Sky layer, by clicking on that layer in the Layers panel. And finally, I'll go up to the Edit menu and down to Copy. By the way, this Copy command would not be available if I hadn't first made a selection, because in order to copy, you have to have something that's selected to copy. If I hadn't first made a selection, this command would be gray, just like the Fade command is now. But I do have Copy available so I'm going to select it and then I'm going to create a new image in which to paste the selected sky.
So I'll go to the File menu and I'm going to choose New and the new image opens to the same width and height as the image from which I copied the content. So, I'll just click OK and that creates a new document, Untitled-1, and I'm going to paste my sky into this document by going to the Edit menu and choosing Paste. Now I see the sky in the new untitled document and in the Layers panel for this document I can see that I have a new layer, Layer 1, that contains that pasted content. So that's one common use for using the Select All command.
I'm going to go back to the lighthouse file to show you another situation you may run into when you're going to want to use Select All. I'm going to deselect this selection by going to the Select menu and choosing Deselect. Before I use the Select All command in order to crop this image, I'm going to show you that there is more to this image than meets the eye. When I made this image, I actually dragged the foreground landscape into a larger image of sky and there is more sky around the edge of the document that you can't see right now. To show you that, I'm going to go up to the Image menu and I'm going to choose Reveal All.
You can see that there is this border of extra sky all around the foreground landscape. There is no need to leave this content in the image. All it's doing is inflating the file size. If you go down to the Document Information area at the bottom of the document window and click the arrow to the right of that Document Information field and choose Show > Document Sizes, you'll see two numbers. The number on the right represents the file size of the image with all of the content on both of the layers, including the extra content on the sky layer, and notice that number is over 3.5 megabytes.
I'm going to use Select All along with the Crop command to get rid of this extra bit of sky that's inflating the image size. First, I'm going to undo by pressing Command+Z on the Mac or Ctrl+Z on the PC so that you don't see this extra bit of sky. The next thing I'm going to do is use the Select All command. I'll go up to the Select menu and I'll choose All and as before, this creates a selection around all the visible content on the image canvas, but that doesn't include that extra border of sky that's on the Sky layer.
To eliminate that from the image, I'm now going to crop to this border by going up to the Image menu and choosing Crop. You won't see any difference here in the visible canvas, but take a look at the image size. As you can see, it's decreased by over 1 megabyte. I'll deselect by pressing Command+D on my keyboard, that's Ctrl+D on a PC keyboard, and just to prove to you that border is gone, I'm going to go back up to the Image menu and again choose Reveal All. This time, there is nothing more to reveal because I've cropped away that extra bit of sky using the Select All command along with the Crop command.
So those are a couple of situations in which the Select All command will come in quite handy.
- Selecting manually with the Marquee, Lasso, and Pen tools
- Saving time with automatic selection methods like the Quick Selection tool and the Magic Wand tool
- Fine-tuning selections with Refine Edge
- Working with selections in Quick Mask mode
- Moving, modifying, and combining selections
- Saving selections as alpha channels
- Making complex selections from color channels
- Using the Background Eraser tool to replace a background
- Installing and using the legacy Extract plug-in to isolate an object from its background