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Alex Hare Photography

Exposure Blending with Luminosity Masks
Post Production & Digital Imaging Techniques

Jul 15th 2015

As a follow up to my recent post, and to expand on the existing tutorials I’ve posted about using Tony Kuyper’s Luminosity Masks, I thought I’d show you a walk through of processing a photograph with them that involves a blend of two exposures.  You can search for previous articles in the 'search' box on the right hand side.

Exposure blending is probably the most common use I find for the masks Tony has created.  It’s always a problem accurately blending two exposures that capture the full dynamic range of a scene but these masks make it a whole lot easier.  So here we go…

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Step 1

Find the two shots you want to blend in Bridge or Lightroom.  As you can see here in the two selected shots on the right in the screen grab below, one is darker than the other, so the dark one is my ‘sky’ exposure and the bright one is my ‘foreground’ exposure.  I need to blend the sky from one with the foregroud of the other so both parts of the shot are perfect.

Step 2

Process the RAW files as you see fit.  I use Adobe Camera Raw but Lighroom is fine (it’s actually the same thing).  When you do this, you’re looking to make the part of each shot you will keep after the blend look as good as possible, ignoring the part you know you will discard.

Step 3

Open them both in Photoshop.  We need to now place the lighter one on top of the darker one as a layer and so we can select the sky part and paint it out to reveal the better, darker sky, from the image below.

Step 4

Make the selection of the sky.  This is where it gets less proscriptive and more subjective from shot to shot but if you refer to previous posts on Luminosity Masks you’ll understand how they work and how they identify pixels within the boundaries of any given selection.

Here, I found a ‘Bright Lights’ selection gave me the necessary separation between the sky and the edges of the land, i.e. the rocks, castle and then the sea/horizon.  Although the sky wasn’t perfectly selected (because it’s not all white in the mask, more shades of grey apart from the sun, which is 100% white) I knew that I could pass the brush over these shades a few times to build up the level of paint that would then reveal the layer below and yet leave the land/rock/sea area untouched because this is, of course, entirely black and therefore completely untouched by the paint brush I pass over it.

Step 5

Back to the layers panel now and with a mask in place we can start to paint over the sky with the paint brush set to black and 100%.  With the selection in place, we'll only be applying black to the sky area and this will, therefore, reveal the sky from the shot in the layer below.

Here’s what the mask looks like after I’ve added black paint to the sky after one brush stroke:

After two passes with the paint brush it looks like this:

Note how the bottom half is almost all white and the edges are very defined between sky and land.  This means the edges are perfectly clear between where the blend between the two shots is taking place and there's no inadvetent bleeding in these areas.  The dashes of grey on the rocks within the white area are parts that are quite bright and have also been selected; this is usually fine as they often look natural having some darker tones revealed from the image in the layer below.  If not, you can very quickly restore them by zooming in and painting white over them to restore them.

Here's the mask after a few passes with the paint brush; the sky is now completely ‘removed’ and the black is 100% in all areas now so all the sky from the shot below this layer is, therefore, revealed.  As the rest of the image is white (apart from the odd grey bit), this means that it blocks any of the (darker) tones from the shot below coming through, which is great because this is the foreground area I want to keep from my pic on the top layer.

The edges are perfect; there’s no ‘bleeding’ from a soft paint brush applied to the sky that clips these edges where no mask is in place to separate one from the other.  There’s no complicated use of small brushes, zooming in and working painstakingly on edges.  It’s just a few wipes of the paint brush and it’s a perfect selection.  Processing Utopia?  It has to be close!

You’ll note that some of the sea in the mask shot above has been painted black.  This could be a problem and require painting out via a more specific selection for just this area but in the end it was fine; the sea was also too bright and by painting it out and revealing the darker sea from the shot at the bottom of the layer stack I’ve brought in most of the darker tones for this area from the shot below and they look fine; natural and in harmony with the rest of the shot, so no problem.

This shot is now done and I can now go on to apply various other adjustment layers to further process the image for contrast, saturation, levels etc before flattening, saving and archiving.

Here's the two shots, side by side, so you can see the difference.  On the left is the blended exposures and on the right is the original, 'bright' exposure.  Hopefuly this illustrates how the blended shot captures both the tones in the sky and the details in the foreground rocks from the 'bright shot' and indicates why the blend was necessary in the first place to address that washed out looking sky and how seamless it can be done with Tony's Luminosity Masks.

If you've enjoyed this article, please consider 'liking' tweeting or sharing it with friends.  This blog is free for anyone to use as an information resource and building an audience is vital to make it viable to continue publishing it.

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