– this subtracts the smoothed out layer from the star filled layer below, and gives the background sky the expected black colour. The next thing we want to do is to change the Blending Mode from “Normal” to “Difference” Now, go back to the Layer tool Menu and select Layer Properties

So go back to the Blur tool (in Effects) and repeat the Gaussian blur with the same value as before. Now press Ctrl+A to select the full layer area – you can see that the layer isn’t perfect as there’s a bit of an edge to the flood fill area To colour in the selected area with an even level of colour

Then use the Dropper tool to select a colour close to the average colour of the area you have selected Otherwise, select the Oval tool, because we want to set the paler area to the background. Rejoin at the instruction to go back to the Layer tool If there are only stars in the image (and no diffuse nebulae that are still showing), you can skip the next few steps. With the top layer selected, locate the Effects Menu – with Gaussian Blur – and select Duplicate Layer You can now see there are two layers – you have the top layer selected Open the original image (available here – right click and Save Link As… ) I recommend bringing up two of the tool views, for Tools and Layers These are top right of the screen It provides a couple of functions that are very useful for removing light pollution from astro photographs the two functions being the use of Layers and the ability to apply a Blur effect to an image.ĭownload and install it.

is a free software package, that was initially created as an exercise to improve the very basic MS Paint program that came with generations of Microsoft Windows versions.

Light layer of paint ms paint