Creating a 4 Point Star Effect

This 4 Point Star effect simulates the effects of star filters used on cameras. In this tutorial, you will learn how to simulate star filters by finding the light sources and bluring them to create a star shape.

	1. Open the image for editing. For this tutorial, select an image with more than one light.
	2. Duplicate the "Background" layer (Ctrl+J).
	3. In the Levels window (Ctrl+L), drag the black Input Slider to the very right side so it under the white Input Slider. Click OK.
	4. Change the top layer blending mode to "Difference". The artifacts you see are where the stars will be. Using the Eraser tool, erase all the artifacts in areas where stars don't belong. Using the Brush tool, paint around artifacts that are too thick to make them about the same size as the other artifacts. Rollover the image on the left of this step to see what this image looks like after this step.
	5. Duplicate the top layer and rename the new layer to -45 and the middle layer to 45. The names represent the degree of the star.
	6. For layer "45", apply a "Motion Blur" (Filter> Blur> Motion Blur) with the following properties: Preview: On Angle: Layer name Distance: Size you want your star to be. Select 50 if you want your star to be 50 pixels. Click OK. Apply another "Motion Blur" to the same layer but set the "Distance" to 150% of the "Distance" you've applied earlier (ex. If the previous distance applied was 50, the next one should be 75). Repeat this step for layer "-45".
	7. Merge the top two layer together (select the top layer and press Ctrl+E) and set the blending mode for the top layer to "Screen".
	8. Apply "Auto Levels" (Image> Adjustments> Auto Levels).
	9. Apply a Gaussian Blur (Filter> Blur> Gaussian Blur). Select a "Radius" small enough to remove any sharp lines. Click OK.
	10. The 4 point star is not visible on all bright areas of the image. Try creating more layers in step 5 and use different degrees to create different stars. Rollover the image in this step to see the original image before this technique was applied.

This effect works by finding the lightsource of the photograph. It then uses motion blurs to create the shape of the star. Although this effect can create many different types of stars, it's inferior to real star filters. Star filters differs in size depending on the brightness and distance of the light source.