Centre weighted ND filter ------------------------- Author: Berthold Daum, CompuServe-ID: 100026,3365 Platform: Windows Implementation: Filter factory Application: RGB images only The centre weighted ND filter corrects the natural brightness fall off towards the edges of an image that was created with a wide angle lens. This fall off is caused by the geometry of the lens and does not include additional fall off caused by bad lens construction or unsuitable filters or lens shades. To install the filter: Copy radgrad.8bf into the PLUGIN folder. Restart PhotoShop. To use the filter: For corrective purposes the filter should be used only with uncropped images. Set the focal length slider to the focal length of the wide angle lens the image was made with. 42mm is considered as the normal focal length (35mm format). For other formats first convert the actual focal length into the 35mm equivalent. The effect slider controls the amount of correction. The centre position is neutral. Move the slider to the right for corrective purposes. Move the slider to the left to apply additional fall off. Notes: As with every filter factory filter a lot of RAM is required (it seems that the filter factory cannot make use of virtual memory) and the filter can only be applied to RGB images. We trust that future versions of PhotoShop will address this problem.
Kot_Maciek