Using the Extract Filter

You now know that there is more than one way to extract an image from its background. You can use the Magic Eraser to remove simple, solid color backgrounds or use the Background Eraser to remove detailed backgrounds. But there is also one other more-advanced tool that you can use to extract an image from its background: it’s called the Extract filter. Depending on the image you are working with, the Extract filter may require a little more effort, but the results are always worth it. I find it to be a much better tool than the Background Eraser for making detailed extractions. For example, the butterfly with all of its soft fringe edges is a perfect image to use with the Extract filter .

The Extract filter works like a cross between the Magnetic Lasso and the Magic Eraser. It allows you to outline an object and extract it from its background. You can access the Extract filter by choosing Filter --> Extract. This launches a whole new interface, complete with a large preview window and its own set of tools.

When you launch the Extract dialog box, the image layer you currently have selected appears in the preview window. You can then indicate what the foreground and background areas are by outlining the image with the Edge Highlighter tool.

By enabling the Smart Highlighting option under Tool Options, you can limit the amount of highlight paint that covers a well-defined edge. Doing so ensures a much cleaner and more accurate extraction. In addition, Smart Highlighting automatically recognizes well-defined edges, which can help guide your path as you draw.

Select First and Then Extract
To limit what appears in the dialog preview window, select an area of the photo with one of the marquee selection tools before launching the Extract filter.

By default, the Edge Highlighter color is bright green. However, if this color conflicts with the photo you are working with, you can choose Red or Blue from the Highlight drop-down list, or choose Other to select a different color with the Color Picker. You can change the brush size by entering a different pixel amount in the Brush Size field located under Tool Options. You can also change the brush size by clicking the arrow next to the field and using the pop-up slider, or by pressing the left and right bracket keys. Use smaller brush sizes (along with Smart Highlighting) for better extraction results. As you outline with the Edge Highlighter tool, you can navigate around the image by using the dialog’s Zoom and Hand tools. If you prefer, you can hold F/Ctrl while pressing the plus or minus key (use F/Ctrl++ to zoom in, and F/Ctrl+ – to zoom out). You can also press and hold the spacebar to temporarily access the Hand tool.

When you’ve finished marking the edges of the areas you want to retain, select the Fill tool and click inside the outlined image area. Photoshop fills the image area with the chosen fill color. The default fill color is blue, but if this color conflicts with the photo you are working with, you can choose Red or Green from the Fill drop-down list, or choose Other to select a different color with the Color Picker.

Click the Preview button in the upper right of the Extract dialog box to see the extraction before it is applied. The Display drop-down list allows you to choose whether to view the highlight and fill in addition to the extraction.

The Display drop-down list allows you to choose from several display options for the selection area background. The default None setting displays the selection over the current transparency display preference. Unless you’ve changed it, this displays the default gray-and-white checkerboard pattern. Previewing over this background can make it very difficult to see any unwanted small pixel artifacts that didn’t get erased. It also makes it difficult to see any unwanted fringe pixels remaining around the edges of the object. To clearly see what was erased and what wasn’t as you’re previewing an extracted selection, the best background color choice is White Matte. If necessary, you can fine-tune your selection by using the various cleanup tools and can and update it by clicking Preview. Here are some tips for improving your extraction:
- To edit the outline edge of your image as you draw, temporarily switch to the Eraser tool. Subtract from the selection by holding down Option/Alt and painting over it with the Edge Highlighter tool.
- After filling the outlined image area and clicking the Preview button, smooth the edges of the mask to make them more transparent by painting over them with the Cleanup tool. Hold down Option/Alt to make the edges more opaque. To control brush softness/hardness, press the numbers 1 through 9 on your keyboard—1 being the softest and 9 the hardest.
- Clean the edges of the mask by drawing over them with the Edge Touchup tool. Hold down F/Ctrl to move the edge. Press 1–9 to control the pressure.
- Enable the Textured Image if the foreground image is too similar in color to the background but differs in texture. Doing so tells Photoshop to look for differences in texture as well as color, which can produce a much better result.
- For objects that are too small and intricate to trace around, cover the entire subject with the Edge Highlighter tool, and then turn on the Force Foreground option. Click on the color of the object with the Eyedropper tool to tell Photoshop what areas to extract. After your selection is complete, click OK to apply the extraction. If the Layers palette is not visible already, choose Window --> Layers. Notice that the object now resides on a single, transparent layer extracted from its former background. To save your extracted image without overwriting the original photo, choose Save As and name the document something different.