Exercise 22 Addition

For this exercise you’ll add one element from a different image.  In order to make this les obviously full intervention, the exercise will be in two stages.  The aim is to take a conventional landscape view and render the sky so that it appear ideally exposed with every detail of every cloud visible and textured.  With a cloudy or partly cloudy sky this is frequently a problem.

Set up the camera on a tripod so that you can make more than one exposure in perfect register.  Make two different exposures with the camera on either manual settings or using its exposure compensation.  One exposure should be perfect for the landscape (the sky will be overexposed) and the second exposure should be perfect for the sky with no highlight clipping (the landscape will then be under-exposed).  Process the two images normally without significant compensation and combine these two images as the next step.

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Roof Tops

Image No : DSC_007.jpg, exposed for the roof tops

Image information: focal length – 18mm, exposure – 1/400^th @ f10, ISO 200.

Image No : DSC_008.jpg, exposed for the sky

Image information: focal length – 18mm, exposure – 1/500^th @ f11, ISO 200.

First thing I have to do is drag a copy layer of the sky exposure on to the roof tops image and select the sky using the Magic Wand tool.

Then I removed the sky using the delete key on the keyboard, flattened the whole image and saved a copy.

Exposed for sky removed and image flattened

I went back to the original two images and again dragged a sky exposed layer on to the rooftops image.  This time after I had selected the sky I used Select/ Inverse to capture the rooftops.  If you look carefully you can see the ‘marching ants’ around the lower part of the image.

I used the delete key again to remove the bottom half of the Roofs image, then flattened the layers and saved the image and you can see the completed image below.



My two images look virtually the same, as they should but it gives you control over the various areas that would normally come out darker. 

Another way of doing the same is to use the HDR facility found in Photoshop from at least version CS4 where you use a tripod and take several images exposed for the various areas of the picture.  A good example would be a church where you would have very dark areas – high roof areas, dark areas – mid level roof areas, mid tone areas – the pews, light tones and very light tones such as a stained glass or glass window. 

The HDR facility takes all the images and combines them into one with reasonable exposure in all the areas and comes up with one image.  If you used a tripod then the images should meld into one seamless image.  Some people like the effect and others find it disconcerting that all areas are exposed perfectly when they would have expected light and dark areas.