Using the Filter Gallery
To open the Filter Gallery, choose Filter > Filter Gallery, select a filter category, and then choose the filter to apply. Many filters use the currently selected foreground and background colors as the colors applied by the filter, (see Figure 1). If you don’t like the colors of the image after applying them (for example, the torn edges or plaster filters are not to your liking), exit the Filter Gallery, select different foreground and background colors, and reapply the filter.
Figure 1 The current foreground and background colors are used in the plaster filter as the colors for the effect.
A smarter alternative is to apply the filter even if the color is not to your liking and click OK to close the Filter Gallery dialog box. Choose Edit > Undo to undo the filter, change the colors, and then reapply the filter by choosing Filter > Filter Gallery—ensuring that the Filter Gallery option you choose is the first one listed in the Filter menu. This process simply reapplies the filter with the same settings as last time and your new color combination.
To return a filter’s options to what they were when you opened the Filter Gallery, press Alt (Option on the Mac) to turn the Cancel button into a Reset button and then click it.
To apply multiple filters to an image using the Filter Gallery, apply the first filter, press New Effect Layer in the foot of the Filter Gallery, and apply a second filter (see Figure 2). You can remove either filter by clicking its visibility icon in the Filter Gallery; you can alter their order of application on the image by dragging one under another. This feature enables you to compare the effect of applying different filters without exiting the Filter Gallery dialog box.
Figure 2 The Filter Gallery enables you to apply multiple filters at a time to an image and to change the order in which they’re applied.
Because Photoshop filters permanently affect the image layer they are applied to, they’re hard to undo at a late stage of editing the image without losing all subsequent changes. For this reason, you can apply a filter to a layer that contains a new flattened version of your image. To do this, add a new layer at the top of the stack, select it, and press Ctrl + Alt + Shift + E (Command + Shift + Option + E on the Mac) to create a flattened version of your image without destroying all the layers you have already created. Apply the filter to this layer so you leave the remainder of the image intact.