Editors' Note: To ensure that this plug-in works, you must use Best Color Matching (instead of Faster) in the Index Color dialog box when doing your Indexed Color mode conversion. Otherwise, the converted image may not use the newly added pure black and pure white palette entries.
Due to the way Photoshop 5.0 currently handles color conversions, black-and-white images--when converted to an Indexed Color palette--often lose their pure black and white color extremes. When installed in Photoshop's Plug-ins folder, the Force Black and White Extension Plug-in forces Photoshop 5.0.x to include pure black at the beginning of the palette and pure white at the end of the palette whenever a document is converted into the Indexed Color mode using the adaptive palette. Images converted in this fashion will work in the applications that require pure white and pure black palette entries, but the colors chosen will be slightly less optimal for the image since there are two fewer available.