Light pollution is a bad problem, as we all know, and sometimes LPS filters are not practical or do not produce the result we desire. Here is a tip I recently learned to deal with the horrible light pollution that is present in my own backyard. Here is a single short test exposure illustration to bad LP at my location.

http://autostarsuite.net/photos/kaos/Single_Light_Pollution_exposure.aspx

Using the Gaussian blur function in Paint Shop Pro X2 set at about 60 (it will vary from night to night depending of the amount of pollution

The following image is the result of about a 60 Gaussian blur of the original photo.

http://autostarsuite.net/photos/kaos/Gaussian_Blur_of_LP_Photo.aspx

Once you have the burred image, subtract it from the original image. Here is the original image with the blurred image substracted.

http://autostarsuite.net/photos/kaos/picture16651.aspx

As can be seen, the subtraction cleans this original light polluted image up quite nicely. Notice the marked increase in the signal to noise ratio.

I have had some success with the IDAS LPS PIII filter, but expousre times are increased by about half to 3/4's.

Hope this is helpful to folks like me who are swamped by light pollution.

Kaos

Someone asked me if the Gaussian blur function was available in Photoshop. Although I do not use Photoshop, I understand that it is. You will have to experiment with the Gaussian blur settings to find out which setting works best with each raw photo. If anyone knows for certain...please post your comments. Thanks

Kaos