Working with the Background Eraser tool
Video: Working with the Background Eraser toolYou may not have thought of using an Eraser tool to help you make a selection, but the Background Eraser tool, which is located here in the toolbox, can come in handy when you want to isolate a complex foreground object, like these leaves and stems from the background. The way the tool works is that it samples whatever color you click on underneath the crosshair, and then it erases similar colors and tones within the circumference of the brush tip. So, if I click right here, I'm sampling blue, and I'm erasing pixels inside of that circumference that are similar in color and tone to the blue one which I clicked.
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In Photoshop CS5: Selections in Depth, author Jan Kabili offers a comprehensive tour of Photoshop CS5's selection features. Selection options are the key to performing creative imaging tasks, such as isolating photo adjustments and making image composites. This course covers selection basics as well as the nuances of selections, including selecting hair, refining masks, saving and recalling selections, working in Quick Mask mode, and creating selections based on image properties, such as luminosity and color channels. Exercise files are included with the course.
- Understanding the when and why of making selections
- Combining and transforming selections
- Selecting fine detail with Refine Edge
- Capturing soft and hard edges in one selection
- Understanding the relationship of selections to masks
- Removing color fringe around selections
- Using the Marquee and Lasso tools
- Working with the Color Range command
- Selecting with the Pen tool and paths
- Making easy selections with the Quick Selection tool
- Working with Refine Mask
- Sharing selections between images
Working with the Background Eraser tool
You may not have thought of using an Eraser tool to help you make a selection, but the Background Eraser tool, which is located here in the toolbox, can come in handy when you want to isolate a complex foreground object, like these leaves and stems from the background. The way the tool works is that it samples whatever color you click on underneath the crosshair, and then it erases similar colors and tones within the circumference of the brush tip. So, if I click right here, I'm sampling blue, and I'm erasing pixels inside of that circumference that are similar in color and tone to the blue one which I clicked.
So if I click and drag, I'm continuously sampling colors from the sky and erasing similar colors and tones within the circumference of this brush. I'm going to revert to bring all that back by going to the File menu and choosing Revert. Before I actually use this tool on this image, I want to set some of its options. First, I'll go to the Sampling options. I'm going to leave Sampling set to Continuous, so that as I move the Brush tool, it's continuously sampling new colors under its crosshair.
I'll go to the Limits field, and I'm going to change that from Contiguous to Discontiguous. When Limits is set to Contiguous, the only colors that will be erased are those that are next to one another, or adjacent. So, for example, if I leave that at Contiguous, and I come into this area, and I make the brush tip bigger by pressing the Right Bracket key, the only pixels that are erased are those that are touching one another, so that those pixels that are outside of the branches, even if inside the circumference of the brush tip, will not be erased.
Now, if I change that to Discontiguous, and I click within an area, even the pixels outside of that area are erased if they're inside the brush circumference and within the range of tolerance. If the tool doesn't erase all of the pixels within the diameter of the brush, I can increase the Tolerance field here to change the range of erasable colors and tones. Finally, if there's a color that I want to be sure not to erase by mistake, like the orange in these leaves, I can set that as the foreground color, by temporarily selecting the Eyedropper tool, pressing the I key and holding it on my keyboard and clicking on that color to set that as the foreground color here in the Foreground Color box.
And then I'll check Protect Foreground Color, and now I'm protecting that particular orange from being deleted by mistake. I'm going to revert one more time, choosing File > Revert, and I'm going to make a copy of the single layer in this file, because this tool actually deletes pixels permanently. So I'll right-click on the leaves layer, and I'll choose Duplicate layer and click OK. I'll make the bottom layer, the leaves layer, temporarily invisible by clicking its eye icon, and I'll make sure the leaves copy layer is selected.
Now, I'm going to come into the image, and I'm going to click on blue, and as I do, I'm eliminating the blue background within the circumference of the brush. So, it's fairly quick to eliminate all of the blue background in between the leaves and stems. Now, I'm not going to make you wait while I do that all around this image, but I want you to understand how the tool works. I'll go ahead and delete the rest of the pixels in between, and around the branches. Now that I'm done using the Background Eraser tool to eliminate the background from in between the leaves and stems here, I'm going to use the resulting transparency on the leaves copy layer to make a selection.
The transparency is represented by this gray-and-white checkerboard that you see here. To load a selection from that transparency, I'll go to the leaves layer, I'll hold down the Command key on the Mac or the Ctrl key on a PC, and I'll click on the thumbnail on the leaves copy layer, and that creates this selection around the leaves and stems. Now, I'm going to make the leaves copy layer invisible by clicking its eye icon, and I'll make the leaves layer visible by clicking its visibility field, and I'm going to select the leaves layer, because what I want to do next is to use this selection to create a layer mask on the leaves layer that will hide the sky without deleting it, as I had to do on a leaves copy layer.
This is a better way to work because it's a nondestructive editing workflow. With the leaves layer selected, I'll go to the Add layer mask icon at the bottom of the Layers panel and click there to create a layer mask on the leaves layer. I'll show you that layer mask by holding the Option key on the Mac or the Alt key on the PC as I click on the layer mask, and here you can see the mask in the document window. The black areas of the mask are hiding the content of the leaves layer, in other words the sky on the leaves layer, and the white areas of the mask are revealing the content of the leaves layer, in other words the yellow leaves and the stems.
Now, I didn't do a perfect job with the background eraser because I was hurrying and so I missed a few spots here, but because this is a layer mask, I can always get my Brush tool, set my foreground color to black and paint over the spots that I didn't completely make black in the first place, like that. And because this is a layer mask, I can use any of the controls here in the Masks panel to refine it, as I've showed you how to do in other movies. But for now, I'm just going to bring back the image by holding the Option or Alt key and clicking on the layer mask thumbnail.
I'm going to create a new layer beneath the leaves layer by holding the Command key on the Mac or the Ctrl key on the PC as I click the Create New layer icon, and that makes a layer beneath the leaves layer. With that new layer selected, I'm going to fill it with white. I happen to have white as my background color, so I'll just press the X key on my keyboard, and that sets white as the foreground color, and I can fill it with the foreground color by pressing Option+Delete on the Mac or Alt+Backspace on the PC.
And now I've replaced that original kind of pale blue sky with this nice, white solid background, and it all started with the Background Eraser tool, a tool you may not have thought of as a selection tool, but one that can often help you to make selections around complex foreground elements like this.
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