Convert a gray track on a transparent background to colour?

[Guy Burns]

I have a gray image (in RGB) on a transparent background. It's actually a thin fuzzy line representing a track on a map. I want to alter the colour so that it becomes, say, a red line and retains the original gradients. I want this to be standalone at the moment, and not be superimposed on the map. i.e. I know how to change the colour by using the track as a layer mask and looking through to a coloured layer underneath. For reasons too involved to easily explain, I can't use that technique in this instance.

The tiff file can be downloaded here.

Thanks in advance for anyone who can tell me how to change the colour of that line.

[Jeff Arola · Accepted solution]

You could use a color overlay layer style by going to Layer>Layer Style>Color Overlay.

[D Fosse]

To me the simplest and most immediate way seems to be a clipped adjustment layer. A Levels adjustment gives you very direct and complete control of an individual color. Here's a dark gray with clipped Levels:

[Guy Burns]

Thanks for the two correct answers. Both are equally good for my purposes.

I haven't used the Layer Styles option before, so it's good to know about that. Levels (I mostly use Curves) I am familiar with, but it didn't click that I could use Levels or Curves. I was trying to be too complicated, using layer masks and saved selections and whatnot. But I thought there'd be a simple method. And there is!

Thanks again.