In photos, layer blending modes enable you to change the way in which pixels on one image layer mix with the pixels on the underlying layer. Some blending modes create special effects, but others prove useful for exposure correction. In Photoshop Elements, you set the blending mode via the Blending Mode menu at the top of the Layers palette.

To use blending modes to tweak exposure, first duplicate the layer that you want to adjust. Then set the blending mode for the duplicate layer according to whether you want to darken or lighten the image, as follows:

• To darken the image, select Multiply as the blending mode. This mode multiplies the brightness values of pixels on the original layer with the brightness values of pixels on the duplicate layer. The result is always a darker, more intense color; however, black and white pixels don't change.
• To lighten the image, select Screen as the blending mode. Screen accomplishes the opposite of Multiply. As with Multiply, black and white pixels are unaffected.

You might think that Multiply and Screen might just be fancy ways of accomplishing the same thing as Brightness/Contrast. But rest assured, by using Multiply or Screen you won't lose nearly as much detail as you do with Brightness/Contrast option.