The best way to remove halos from your pictures

Have you ever noticed a white glow along the edge of a building, tree or mountain in your pictures?
Welcome to the club. It is called haloing.

Halos are artifacts that thrive undisputed in over-processed HDR pictures, whenever tone mapping is pushed over the limit. They are also produced as a result of too high a value for clarity or over-sharpening.
However, sometimes haloing also affect images that would look very clean and natural otherwise.

No matter what their origin is, in today's digital photography halos tend to be perceived as a result of over-processing and, for this reason, I always try to get rid of them.

I made a quick video tutorial to show you my favourite technique to remove halos in Adobe Photoshop.
You can watch it or, if you prefer, just go ahead and read the text. They both illustrate the same concept. 

 

In general, haloing is found in high-contrast scenes. Therefore, you should give your images a careful check for halos whenever you have a dark foreground against a bright background.

Here is my favourite technique to remove halos in Adobe Photoshop:

  1. Create a stamp visible layer, so that whatever you did to your image so far will not be affected by what you do next. If things go wrong with halos removal, you will just delete the newly created layer.
    (PC: Control + Alt + Shift + E, Mac: Command + Option + Shift + E)
  2. Select the Clone Stamp tool.
  3. Set the mode of the Clone Stamp tool to Darken.
  4. Set the opacity of the Clone Stamp tool to about 80%.
  5. Sample a bright area next to the halos.
    (PC: Alt + Click, Mac: Option + click)
  6. Brush the halos to remove them.

For better results, I suggest you zoom in between 100% and 400% before you start brushing. How much exactly you need to zoom in depends on your image.
Try it and let me know your results. I am pretty sure you will be impressed!

This is all you have to know to apply the technique. However, if you are like me, you may be interested in knowing why this technique is so efficient at removing halos. Should it be the case, please keep reading the explanation below.

The secret of the technique resides in setting the Clone Stamp tool in Darken mode.
In Photoshop, modes can be applied to lots of tools and also elements, such as layers.
In particular, the Darken mode compares two sets of pixels in a pixel by pixel fashion, keeping the darker pixel in each pair and discarding the brighter one.

In the Clone Stamp tool case, one set of pixels is what you sample (PC: Alt + Click, Mac: Option + Click) and the second set includes the pixels you brush over.

Consider the picture below. It is a shot of Bled Castle (Bled, Slovenia) I took in December 2016 at blue hour. 

Zoom: 150%. For the sake of the tutorial, I unreasonably increased the clarity to accentuate the halos


The image includes the following elements:

  1. Sky
  2. Roof of the castle + tree
  3. Halos along the roof of the castle and tree

The sky is a lot brighter than the roof of the castle and the tree, but the halos are even brighter than the sky.

Remember: the Darken mode compares two sets of pixels in a pixel by pixel fashion, keeping the darker pixel in each pair and discarding the brighter one.

Since the sky is brighter than the roof, no pixels will be replaced in the roof. On the other hand, since the sky is darker than the halos, the pixels from the sky will replace the pixels where halos are present.

This is how it works. Try it on your pictures and let me know how it goes!

Cheers,

Enrico