Use the Eraser Tool in Photoshop CS5
You may not think of the Eraser tool in Photoshop Creative Suite 5 as a painting tool, but it can be! When you drag the image with the Eraser tool, it rubs out pixels to the background color. If you’re dragging with the Eraser tool on a layer, it rubs out pixels to reveal the layer’s transparent background. (You can think of using the Eraser tool as painting with transparency.)
The Eraser tool uses all the same commands as the Brush tools. You can make an eraser larger or softer or more or less opaque. Even better, follow these steps to use the Eraser tool creatively:
Open any color image and apply a filter.
For example, we chose Filter→Blur→Gaussian Blur. In the Gaussian Blur dialog box that appears, we changed the blur to 5 and then clicked OK to apply the Gaussian Blur filter.
Select the Eraser tool and press 5 to change it to 50 percent opacity.
You can also use the Opacity slider on the Options bar.
Hold down the Alt (Windows) or Option (Mac) key to repaint 50 percent of the original image’s state before applying the filter.
Continue painting in the same area to bring the image back to its original state.
The original sharpness of the image returns where you painted.
Holding down the Alt (Windows) or Option (Mac) key is the key to erasing the last saved version (or history state). This tool is incredible for fixing mistakes or removing applied filters.