Increasing dynamics

The human eye’s brightness ratio exceeds by a great deal that of digital cameras, or even the brightness limits perceived by professional film. Your camera is in trouble when dealing with huge differences in brightness as it cannot represent the view perceived by your eyes. For example, you try to photograph a landscape in the brightest sunlight. Normally, your eyes aren’t tested much by having to compensate the brightness differences between the sunlit sky and the shaded landscape parts. But not so the camera! If you measure exposure at the sky, you can only see black silhouettes of the landscape. If you use the landscape as a basis of measuring, the sky will be unpleasantly white (bleached). One solution for the problem is multiexposition, i.e. taking multiple photos with different brightness levels, and merging them.

We'll need suitable base materials to begin this procedure with- two or more photos of the same topic.

Take multiple photos of the landscape you want to record. The series usually consists of 3 pictures. The camera takes a picture with the exposition value it measures and thinks suitable. Afterwards, it takes a shot with a user-defined correction step lower and higher each. The step is most often a half or one exposure value, but in extreme situations (e.g. very strong counterlight) it may be even greater. If possible, take the photos from a tripod, or at least use sequence mode. For accurate results, a tripod is strongly recommended, as the framing masks have to be the same size. Now you have 3 identical photos that only differ in their lighting levels.

Most of the time, the series consist of 3 images, but we'll only need two of them. Choose the photo where the foreground (landscape, building, etc.) is appropriately exposed, and the one where the background (e.g. the sky) is suitable. Open both in Photoshop. We have chosen these pictures:

You can easily see that in the left photo, the castle and the areas behind it are suitably lit, but the remote landscape is too light, and the sky has been bleached white. In the picture on the right, the original blue color of the sky gets through better, and the remote landscape is acceptable, but the foreground is way too dark. We want to merge the two images to retain the background from the first and the foreground from the second.

Click the lighter picture and press Ctrl+A. You have selected the whole image. Press Ctrl+C to copy the selection (the whole image) to the clipboard. Now click the darker photo and press Ctrl+V. The lighter picture is copied on top of the darker one onto a new layer. This is also visible on the Layers palette on the side of the screen.

We'll work with this double-layered image, so you can safely close the other file containing the lighter one.

Choose the Gradient Tool from the Tools palette. You can press G to do so, but by default this will select the Paint Bucket Tool. Click and hold the left mouse button on it to make the Gradient Tool available.

Remember to keep black and white as the selected colors. Leave the Gradient Tool's settings on default. The most important thing is to have Linear Gradient selected on the left. This creates a gradient that intensifies evenly.

Let's return to the Layers palette. Make sure the upper (lighter) layer is selected, and click the Add Vector Mask icon at the bottom of the palette.

Now press and hold Shift, and click a bit below the part of the picture where you want the darkening transition to begin, and drag the mouse pointer upwards (while still holding Shift) to the upper edge of the image. The starting point can be where sky and ground or sky and rooftop meet. As the transition will be gradually intensifying, you don't need to set the starting point exactly there, it can be placed a bit lower.

The two pictures "fade" into each other in a soft transition, and thus the appropriately lit foreground objects of the lighter picture and the properly exposed remote landscape and sky from the lower, darker layer can be now seen in the same picture. All you need to do is to click Layer/Flatten Image to merge the two layers.