If you’ve been on one of our workshops, one of the things that you will have noticed most is that we mention the histogram rather a lot! It really is the key to accurate exposure in digital photography so understanding it and looking at it after every exposure is essential. Once you’ve grasped what it’s saying, you will no doubt be faced from time to time with one of those tricky lighting situations where your camera’s sensor can’t manage the full tonal range of the subject so the exposure is clipped at both ends of the histogram. To overcome this problem, one of the simplest and most effective techniques is to take two exposures and blend these using a layer mask in Photoshop, which is what we’ll look at in this post.
This is an abridged version of a more detailed additional PDF handout we’ve added for the 2015 workshop season, so if you come on a post-processing session you’ll get a copy of the PDF which covers full Photoshop and Photoshop Elements and some more detail on using camera raw for the original image capture. If you’ve been on a previous workshop and would like a copy then just get in touch! If you’re coming on a workshop, we’ll use participant images created on the workshop to demonstrate this technique, should the opportunity arise to capture them!
N.B. You can click on any screenshot to see a larger version in this post.
First, open the two images side by side in Photoshop as shown above. In this example (image ‘Last Light, Wharfedale’ taken near Cray in Upper Wharfedale) the left hand shot has been exposed for the sky and the right hand for the foreground.
Next pick the Move tool in the toolbar (shortcut V) and click and drag the left hand image over the right hand one. This creates a new layer in the right hand image with a copy of the original. We can close the original left hand document now.
Next, check that Snap is checked in the View menu and then use the Move tool again to align the top image exactly over the lower one – it will seem to snap into place to assure pixel for pixel alignment.
Now open up the Layers palette and add a layer mask to the top layer (using the Add a Mask) icon at the bottom of the palette).
Finally, pick a brush, set the opacity to 100% and paint on the mask over the foreground, adjusting the brush size as necessary to blend carefully along the horizon. This allows the lower, correctly exposed, foreground image to show through.
Once you’re happy with this blended image you can flatten it if you wish, or keep the layers for future reference. You can then proceed and add your standard processing layers to correct levels, contrast and saturation as necessary to produce your final image.