Photoshop 5.5's Background Eraser
The qualities of this image led me to choose Photoshop's background eraser tool. The background in this image is a a similar color throughout the image, and the soft, billowing edges of the vapor trails make the selection tools--such as the magic wand or magnetic lasso--impractical. Using the background eraser and the technique below, I was able to remove the background from this image in just a few minutes.
The background eraser tool samples the background color as you paint and erases pixels in the same color range as you drag your brush across the image. The color range is determined by the tolerance setting in the background eraser options. Since this image had a background that was all over very similar in color, a low tolerance setting was used. I choose the discontigous option because I wanted to remove the blue color everywhere it appears in the layer.
Because part of the foreground in this image is light colored, I find it easier to work with the background eraser by dropping in a contrasting color behind the layer so I can see my work more easily. To do this, I double clicked on the background to promote it to a layer and I named that layer "Jets".
Next, I added a new layer, dragging it below the Jets layer and filling it with solid black. Later, this layer can be deleted or filled with another color.
As you can see below, I like to work with a fairly large brush when using the background eraser tool. You don't want a soft-edged brush either. I find a hardness level of about 80 works well. To customize your brush size and hardness, just double click an existing brush in the brushes palette, or select New Brush from the brush palette menu.
When you click with the background eraser brush in your image, you need to be very careful that the crosshairs in the center of the brush land only in the background area. The crosshairs take a sample for the background color, so if the crosshairs touch the foreground, it will remove part of the foreground.
With my giant brush, I like to make several individual clicks in the image rather than using a click and drag motion. When you make individual clicks, it's much easier to undo a mistake if you click too close to the foreground. Below you can see where I've made two clicks with the background eraser.
I continue clicking until the area immediately surrounding the foreground is completely removed, then I go back and take out the surrounding background with a dragging motion.
|You can see in the enlarged view here that there are some specks from the background that were not completely removed. If you continue to carefully drag the brush around the image you can erase the majority of those specks.|
To make sure all traces of the specks are completely removed, this is what you can do: Ctrl-click on the layer in the layers palette (command-click on Mac) to load the layer as a selection...
Then invert the selection (Selection > Invert) and press delete.
Here is the final image with the background removed and a new background dropped in to replace the black. The total time spent removing the background was under 3 minutes.
It may take a little time experimenting with the background eraser tool options before you can achieve results this quickly, but with a little practice, I'm sure you'll start to see the power of this amazing tool.
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Some images from Nova Development's Art Explosion 600,000.