Many times, I have wanted to shoot a scene only to discover that the dynamic range is well beyond the range of my digital camera to capture. For my Canon 20D, the range is somewhere around 4 stops of light. Using the following Photoshop recipe, you can extend your camera’s dynamic range considerably. One caveat is that this recipe only gives good results about 50% of the time for me.
When faced with either blowing out the highlights or plugging up the shadows, choose to do “both”. Since we are going to combine the images in Photoshop later, I recomend that you shoot from a tripod so that aligning the images is easy. First, shoot for the highlights. Make sure to look at your histogram and make sure that the highlights are not blown out. For this scene, the first shot is for the sky.
Second, shoot for the shadows. Make sure to look at your histogram and verify that the shadows are not plugged up. For this scene, the second shot is for the foreground. To keep the final result realistic, do not overdo. Therefore, I will keep the foreground pasture fairly dark.
Now that the shots are taken, you are ready for the Photoshop work.
- Open the shadows/pasture shot in Photoshop.
- Open the highlights/sky shot in Photoshop.
- Copy all the contents of the highlights/sky shot to the clipboard. Use the Control+A and Control+C combination.
- Close the highlights/sky shot. You are done with it.
- With the shadows/pasture shot selected, paste the highlights/sky shot (Control+V). At this point, you should have a highlights/sky layer above your shadows/pasture layer. You may want to toggle the display of the highlights/sky layer to verify that your images are aligned. If they are slightly misaligned, you can use the Free Transform tool (Edit | Free Transform) to adjust the position of the highlights/sky image.
- A mask on the highlights/sky layer is now required. You want a combination shot which uses the pasture shot for dark areas and light areas from the sky shot. Good news, a grayscale version of your shadows/pasture shot will make an excellent mask. Select the background layer (the shadows shot) and copy all the contents to the clipboard using Control+A and Control+C.
- Add a layer mask to the highlights/sky layer by selecting the highlights/sky layer and clicking on the new layer mask button at the bottom of the layers palette.
- Make the layer mask visible by holding the Alt key and clicking on the layer mask. The layer mask is now visible in the main window.
- Paste the shadows shot from the clipboard onto the layer mask using Control+V. You should now have a grayscale version of the shadows/pasture shot.
- Make the merged image visible by clicking on the highlights layer. Clicking on the layer, toggles the display back to the image instead of the layer mask.
- You may want to fine-tune your highlights mask depending on your results. I did a small amount of fine-tuning of the layers mask by selecting it and bringing up the Levels dialog (Control+Alt+L). I moved the black and white points inward until I liked the result.
This is my combined image.
With the combined image, I will optimize my image using various techniques for my final version.
There are other techniques for combining the same image with different exposures. The Luminous Landscape web site has a very good article called Blended Exposures. My suggestion is to try various techniques until you have a good result and find one that works well with your shooting style.