Enhancing Star Colour

In your efforts to enhance and drag the detail out of faint deep-sky objects, it is very easy to lose the colour in the stars. Or, as a result of long exposures, the cores of your imaged stars get "blown-out" and appear white. This easy process will bring back the colour to your stars and will make a great impact on your images.

Original Image

Have a look at a zoomed portion of the image. You will see that the star core is burned out, and is surrounded by a "halo" of colour. it's this colour that is going to be reintroduced.

Select the Stars

Using the Magic Wand, set at non-contiguous, tolerance 60, click in the centre of a star.

If the magic Wand hasn't selected the core of all the stars, then hold down SHIFT and click in the unselected stars. This will add them to the section.

Conversely, if it has added in non-star parts of the image (galaxy cores, for example), then hold down the ALT key and de-select these areas.

Expand, Feather and Copy

Expand the selection by a few pixels by going to Select > Modify > Expand. Make sure to cover the entire star, including the halo. Soften the selection edge by feathering the selection (Select > Modify > Feather) by a pixel or two.

Copy the stars by hitting "CTRL C". Paste the stars to a new layer by going to Layer > New > Layer via Copy

Saturation and Blur

Open the Saturation control and increase the saturation to about 80% (or whatever suits).

Apply a Gaussian blur, with a value of 1-2 pixels. You might need to play about to get the desired effect.

Blend Mode

Now go back to the Layers palette. Select the blend mode dropdown and select "Colour". You might want to change the Opacity to change the transparency of the layer.

Once you are happy with the results you can then flatten the image. You should now have restored the colour to your stars