Presentation on theme: "Steve Cannistra, Dark Halo Removal"— Presentation transcript:
1Steve Cannistra, Dark Halo Removal Dark halos around stars can result from overly aggressiveuse of deconvolution or unsharp masking.
2Steve Cannistra, Dark Halo Removal Setting up the technique in Photoshop:1. Duplicate the layer (Layer, Duplicate Layer).Smooth the top layer (Filter, Noise, Median). A radius of 5is a good starting point.3. Assign the top layer to “lighten” mode.4. Create a top layer mask (Layer, Add Layer Mask, Hide All).5. The layer should now look like this (next slide):
3Steve Cannistra, Dark Halo Removal Lighten modeOriginal layerMaskMedian smoothed layer
4Steve Cannistra, Dark Halo Removal Removing the halos is accomplished by painting the maskwhite in the areas of affected stars:1. Select the paint brush tool. Make certain color is set to white.Adjust the paint brush diameter so that it is approximatelythe same size as the stars.3. Click on the black mask area to make it active.Paint over the affected stars to reveal the overlyinglighter regions of the smoothed top layer. The dark halosaround the stars should nicely fill in.5. The layer should now look like this (next slide):
5Steve Cannistra, Dark Halo Removal Final image with halos removedMask with white areasrepresenting locations ofaffected stars