How can I change the colour of the lines of a sketch?

[Lisa30849851fp2m]

How can I change a sketch from black/grey to, say, blue without changing the plain white background?

[davescm]

Hi,

Try a gradient map adjustment layer with the gradient running from blue to white.

Dave

[Trevor.Dennis]

I've always like the Colorize option in Hue/Saturation adjustment layers.  The hue and saturation are simple and fast to dial in.

When you add color to a greyscale image in Photoshop it only affects the midtones.  I have used the exact same Hue/Sat setting to the black to white gradient below, and you can see that the black and white areas are showing no colour.  

[Lisa30849851fp2m]

Hi, 
I got around to this a little later than I had hoped but it worked like a charm.

Cheers!