peter wrote:
In a grayscale image, it seems like it is really just shades of black. Now I want to replace the black with another color, so it becomes all shades of ths new color. When I use "replace color", it will put the new color in for the blacks, but the grays remain gray. I want these grays to becomes shades of the new color. Can this be done?
Try this first. Create a new layer over the image. Fill it with perfect blue (R0,G0,B255) and set the layer mode to "color".
There ya go. One way to do it.
Experiment with layer modes.
If you want to have more sophisticated colorization, possibly a color for a particular grey, and another for another grey, try TRI-TONES or DUO-TONES (hell, try QUAD-TONES, too.) That's Mode to GREYSCALE, then to TRI,DUO,QUAD, etc. There are curves you can apply to model them further.
Most people do not understand that "B&W" photography IS COLOR but without hue. All the other important qualities remain (luminance, and so-forth.)
Enjoy.