I have been sent original bitmap tiff file of hand drawn black and white image, with request to darken black lines. When I open in Photoshop CC I change to Greyscale then try to adjust levels and get no change? Is there a way I can do thsi in Photoshop or should I get the original image in different format or is there another Adobe CC product that I should use, like Firework and how do I do this?
Moved from the Creative Cloud to the Photoshop forum. They will be able to help you here.
Levels is OK where some of the line art is not quite black, or not quite white, but if you open a Levels Adjustment layer and see that the histogram is completely pushed up to each end, then it may well have limited effect.
Try copying the layer and setting the copied layer to Multiply.