How to Fix an Overexposed Digital Photo
If you accidentally overexpose a photo with your digital camera, you can easily fix it with a duplicate layer and the proper blend mode. As long as none of the overexposed highlights are completely blown out to white, you can save the image.
These steps use Photoshop Elements but most image-editing programs share similar procedures
Open your image editor and choose File→Open.
The Open dialog box appears. Navigate to the image you want to edit and click OK. The image opens in your image editor.
Choose Layer→Duplicate Layer.
A duplicate layer of your image is created.
In the Layers Palette, change the duplicated layer’s blend mode to Multiply.
This blend mode darkens the image considerably.
If the image is now too dark, lower the opacity of the uppermost layer until you achieve the desired results.
Change the opacity until you achieve the desired results and your image looks good to you.
If your digital image has bright highlights but is otherwise properly exposed, choose Enhance→Adjust Lighting→Shadows and Highlights to open the Shadows/Highlights dialog box. From within the dialog box, you can darken the highlights, and, if desired, increase contrast.