Today’s Question: I saw a tutorial about the Background Eraser tool in Photoshop, and it seemed like a good tool for creating composite images. I’ve never heard you talk about this tool. Is this a tool you recommend for compositing?
Tim’s Quick Answer: No! I do not recommend the use of the Background Eraser tool in Photoshop, because it is a destructive tool (meaning it removes pixels permanently). Instead I recommend using a layer mask to achieve the same basic result.
More Detail: In theory you could use the Background Eraser tool on a copy of the Background image layer, in order to create a non-destructive workflow using a “destructive” tool. However, I consider a workflow employing a layer mask to be much more flexible.
The basic approach in this case involves creating a selection of the area you want to keep in the final image, so that the area to be removed (or in this case just hidden) is not selected.
For example, you could use the Quick Selection tool to select the area to keep, or select the area you don’t want to keep and then invert the selection by choosing Select > Inverse from the menu.
You can then select the layer you want to hide pixels from. If that layer is the Background layer, double-click on the thumbnail for the Background image layer on the Layers panel to convert this layer to a normal layer. Then click the “Add a Mask” button (the circle-inside-a-square icon) at the bottom of the layers panel to add a layer mask to the current layer based on the current selection.
You can then, of course, continue fine-tuning the layer mask for your final effect, such as by painting on the layer mask with black to block pixels or white to reveal pixels.