Photoshop has a half tone filter, but I don't recall a half tone 'circle' filter. In any case, if you want to apply a filter to the whole image, the filter should automatically center itself. Some filters (for example, Lens Flare) allow you to click a specific area in the image to indicate where you want it centered. If you want to apply a filter to a specific area of the image, select that area first before applying the filter.
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