Step 11: Change The Blend Mode Of The Stars Layer To Screen

Everything's looking good, except for the problem I just mentioned with the glow from the city lights, or more specifically, the sudden and complete lack of any glow from the city lights. Let's finish off the effect by bringing the glow back, which is very easy to do thanks to Photoshop's layer blend modes!

First, I'll select the Stars layer in the Layers panel by clicking on it. It will appear highlighted in blue, letting me know it's selected. Then I'll go up to the blend mode option in the top left corner of the Layers panel and I'll change the blend mode from its default Normal to Screen:

With the blend mode of the Stars layer set to Screen, the glow from the city lights now reappears in the image, making it look more realistic:

Step 12: Colorize The Stars With A Hue/Saturation Adjustment Layer

Let's finish off the effect by adding a bit of color to the stars. This part isn't absolutely necessary, but I find that the stars look nicer with a little color. For that, we'll use a Hue/Saturation adjustment layer. Once again, hold down your Alt (Win) / Option (Mac) key and click on the New Adjustment Layer icon at the bottom of the Layers panel:

This time, choose Hue/Saturation from the list:

Just as we've seen twice before, holding down the Alt (Win) / Option (Mac) key opens the New Layer dialog box before the adjustment layer is added. Once again check the Use Previous Layer To Create Clipping Mask option so that our Hue/Saturation adjustment layer affects only the Stars layer, not the original image, then click OK to close out of the dialog box:

In Photoshop CS4 and higher, the options for the Hue/Saturation adjustment layer will appear in the Adjustments Panel. In Photoshop CS3 and earlier, a separate dialog box will open. To colorize the stars, first select the Colorize option, then drag the Hue slider to select the color you want to use, keeping an eye on your image to preview the color as you drag. I find the stars look best with a little blue added to them, so I'm going to set my Hue value to around 220. The default Saturation value of 25 is too intense, so lower the Saturation to around 10 for a much more subtle colorizing effect. When you're done, click OK to close out of the Hue/Saturation dialog box (Photoshop CS3 and earlier):

Here, after adding a little blue to my stars (the color is a little hard to see in the screenshot but you'll be able to see it better in your own image), is my final "Starry Night Sky" result:

A Fix For A Potential Problem

Some people have reported a problem with the adjustment layer effects disappearing on them when trying to save the final result as something other than a Photoshop .PSD file (like a jpeg, for instance). If you run into similar problems and things don't look right when you go to save your completed effect, first click on the Levels adjustment layer in the Layers panel to select it. Next, click on the New Layer icon at the bottom of the Layers panel to add a new blank layer above the existing layers. With the new layer added, hold down your Alt (Win) / Option (Mac) key, go up to the Layer menu at the top of the screen and choose Merge Visible:

This will merge all of the existing layers onto the new layer. Everything should now look correct when you save it:

And there we have it!

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