Wow. Bit confusing this. A colour bitmap has no greyscale, but its relative luminosity can be measured. Converting colour to greyscale is not an exact science. Desaturation is the obvious method, but for instance, if you desaturate or convert to grayscale a RGB image, it will be different to a CMYK one. The only accurate way of doing it is to covert your source colour to grayscale, and then use the eye dropper and read the info palette for the resulting % mix. Hope this helps. May I ask WHY???!!! Rob