Separation Layers – Advanced Photoshop Technique – James Allan

Amazon 1

I love detail – particularly in birds feathers.  Have a look at the photograph of the Amazon Parrot above.  Every fiber in every feather beautifully arranged as if it had been coiffured.  This bird was in an aivary and I was shooting through strongly sun-lit bars.  The original shot straight out of the camera is below.

Amazon 2s

Incredible.  How do I deal with those unattractive grey bars across the middle of the picture?  Truth is I didn’t know at the time that I took the picture.  The clone tool was useless as it is nigh on impossible to preserve that intricate architecture of the feathers.  If you look closely in the grey areas you can see the feather detail preserved.  I needed to change the contrast and the colour without losing the detail.  I had tried to do this with adjustment layers.  The following is the best that I was able to achieve.

Amazon 3s

I had done a pretty good job, but I couldn’t match the colour of the other feathers and the distortion created by the bars was still  obvious.  I gave up and put this picture in the dud collection.

Several years later I discovered a new technique – using separation layers.  The idea is to create one layer for the colour and another for the detail.  Then it is a simple job to paint over the unattractive grey without losing detail.  As it turned out I needed a third layer to handle shadows.  I gave this a go and got the much more pleasing top photo.  You can of course still see where the bars were, but to the casual observer it is far from obvious.

So how is it done?  I used Adobe Photoshop.  You don’t have to understand the reasons, just follow the steps below as I have recorded them.

  1. Duplicate the background layer twice.  Label the two new layers as “Detail” on top and “Colour” below
  2. Blur the “Colour” layer.  (Before you start you will have to turn off the visibility in the “details” layer and select the “Colour” layer to make it active.)  The Gaussian blur is in the filter menu.  Experiment a bit with the diameter of the blur.  You want to remove all of the detail that you are interested in, while preserving the colours of the image.
  3. Subtract the “Colour” layer from the “Detail” layer.  (First restore the visibility of the “detail” layer and select this as the active layer.)   In the ‘Image’ menu you will find the ‘apply image’ dialog.  When the dialog appears you have several settings to change.
    1. In the ‘layer’ box select “colour” layer.
    2. In the ‘blending’ box select “subtract”.
    3. In the offset box type 128
    4. The other boxes should have Opacity 100% and Scale 2
  4. Blend the “Detail” layer into the “Colour” layer.  In the layers dialog you can find the blending function in a box in the upper left of the frame.  It will say “normal”.  Change this to “linear light” from the drop down menu.

Once the two layers are blended the original image should now reappear. However the image is now a sandwich of two layers, rather than a single image.  Now you can make changes in the colour layer – which will preserve the detail.  For instance I repainted the green of the parrots feathers.   I used both the paint brush and the clone tool.    Alternatively you can make changes in the detail layer – which will preserve the colour.  For instance I sharpened where the bars had been to give the feathers a clarity consistent with the rest of the image.

My assessment.  It is not perfect and will take a bit of practice to master.  However a very useful tool for working with less than perfect images.  As well as unsightly aviary bars it can assist in restoring details where a drop of water was on the lens.  It can be used in portrait photography.  If you have some time – it is worth playing around with.


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