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Enhancing skies in Photoshop

Most outdoor photos can be improved by doing a bit of work on the sky. I don't know why it is, but skies out of camera look insipid, particularly if, like me, you shoot raw files.

In most cases a levels adjustment will perk up the sky.

In order to do this you need to select the sky for the adjustment. There are various ways of doing this, for example you can use the quick select tool and maybe apply a feathering of the edge. (Select, Refine). However if there are hard edges present, e.g. the built environment, this might not be appropriate. You might then consider using more precise selection methods, for example the Polygonal selection tool or the Pen. Both of these tools require skill, time and patience. Quote often there are both soft and hard edges, when quick select accompanied by a more accurate method can be employed. In that instance it might be necessary to feather the soft edges by painting on or erasing from the layer mask [2], e.g. where there are trees etc.

There are quick and dirty alternatives.

If you have Lightroom you can select a broad area for treatment, and use a gradient to taper the effect. This works if there is a clear linear division between sky and land, but, to the best of my knowledge, there is currently no accurate selection tool available. So if you have bits sticking up into the sky you may need to do something else.

Enter the Select by Color range tool in Photoshop. You can pick one or more spots in the sky and, if you are not unlucky, the entire sky region will be chosen. Often you may have to deselect areas in the remainder of the image. I have found this to be the most efficient means of selecting a sky, it doesn't always work, but mostly it does.

Having selected your sky, opt for a levels adjustment layer [1], and gently nudge the two edges of the histogram together. Don't go too far as you will seriously damage the image by introducing excessive noise and/or banding. You may need to use the layer mask [2]  in order to add or remove sections to be treated.

Now invert the selection and apply an adjustment layer to the remainder of the photo. You don't have to stop there of course, you can make as many selections and adjustment layers as you feel fit!

OK that's the easy bit, now to get a tad more involved.

Noise shows up in skies and you may have to reduce it in some way, particularly if you intend to do some enhancement. Applying a noise filter to the whole image is not a good idea as it will damage the detail. However skies don't include detail, so you can severely blat that area with a filter.

Probably the best way to do this is to start by making two raw conversions in Lightroom, one without and one with  noise reduction. You can then combine the two conversions in Photoshop ( copy one onto the other, it will appear as an additional layer) and use the selection tools above to pick the sky. Delete the remainder of the image on that layer and then flatten the two layers. You should end up with a noise controlled sky, that will stand some enhancement, and sharp details elsewhere.

If you don't have LR, then there is a noise filter in PS which you can use in a similar way.

I generally apply a curves adjustment layer to my images, but occasionally this will create banding in the sky. You can get around this by copying the layer mask [3] from the adjustment layer that does not include the sky to the curves adjustment layer. This will remove the curves adjustment from the sky.

Finally, when you come to remove dust spots from your photo, you may find that the color selection is preventing you from using the various tools. Don't despair, flatten the layers and all will be well.

One day I might add some illustrations ......

For those unfamiliar with some of the terminology :-

[1] Adjustment Layer

Can be thought of as being analogous to a filter over a camera lens. It can't change the content, but can vary the brightness, colour, saturation or contrast. You can't copy and paste, or clone stamp, or spot heal onto an adjustment layer, as you don't have access to the digital content.

You can go back to your adjustment layers at any time and alter the settings, or delete them if you wish. When I have finished editing I generally go through each layer in turn switching it on and off, to check the effect, and this often leads me to make further minor adjustments.

Use Layer, New Adjustment Layer

[2] Layer Mask

This masks off some of the adjustment layer so that only part of the image is affected by the layer. When you select a section of the image and apply an adjustment layer, a mask is automatically produced. If you have feathered the edges of the selection, the mask will show a feathering of its opacity at the edges.

You can edit a mask by painting over it to extend it, or erasing part of it to reduce its size. You can also copy a mask from one adjustment layer to another. The mask icon appears to the right of the layer icon in the layers palette. To see the extent of, and edit the mask, go to Channels and click in the square to the left of the named mask.

If you have created an adjustment layer without making a selection, no mask will be produced. However, by selecting Channels and choosing Mask, you can paint on the adjustment layer and make a mask. The mask symbol will then appear in the Layers palette. You may, for example, want to lift the exposure without affecting the highlights, or push some parts of the image into the highlight region, without burning out existing highlights.

[3] Copying a layer mask

Click on the mask and then use Ctrl Alt (Windows) and drag the mask down to the required layer.

If you wish you can Invert the mask by clicking on it and choosing Ctrl I. This is useful if you have done some work on a layer mask and wish to preserve that work in the inverted copy. (Just using Select, Reselect, Inverse does not include any changes that you have made to the mask.)

Edited 9-2-18


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