>It should be quite a simple job to adjust the black point for a bitmap to make any shade of grey truly black. It you have a bitmap editor with a levels control, you can adjust the end points of the black-white range of image.

My experience on many occasions is that the transformation by Therion makes the resulting image appear grey.  I don’t think it is a fault of the original image (but I have not ever looked into it in detail).

Bruce