Merging two images to create a more balanced exposure
Sometimes with a sunset or sunrise image it is
difficult to get a proper exposure of both the foreground and the sky
without losing detail in either the highlights or shadows. The art of
combining exposures at different exposure levels to achieve a single image
the preserves the detail on either side is called High Dynamic Range (HDR)
processing. There are tools specifically designed to automate this
processing such as Photomatix. When used properly they can produce
nice results, but if used improperly such automated tools can produce overly
garish results with unnatural looking colors or contrasts. The
approach below is a more simplifed method for combining two image to achieve
the same goals, but preserving a more natural look.
- Load both images
as separate layers by:
Menu: File -> Scripts -> Load files into stack
Make sure to also click the check box to automatically align the layers.
- Select the top layer and add a graduated filter
mask by selecting the add a layer mask via clicking on the symbol at the
bottom of the layers palette (Rectangle with the hole in it).
- Click on the gradient tool (G on the keyboard),
select the desired gradient mask mode, and draw a line to define the
gradient start and end point (the white portion is allowed through of
the top layer).
or
You can create a more selective mask between the layers by using the
magic wand tool instead of the gradient tool for creation of the mask on
the top layer.
It is this step where you may find yourself spending the most time.
There are many ways you can create or manipulate the mask the defines
how the two images are combined. It is often necessary to use the brush
tool with a particular softened edge and opacity control to manually
edit the boundary and amount of strength to combine from each image.
- Adjust the exposure on each layer separately via
the adjustment tools such as curves, etc.
-
Control the strength of the top layer via the opacity slider in the
layers palette.