Selection question -Affinity Photo (Mac)

[Jeff_]

Hi there, I have a photo that I'm editing and have been stumped for a few days trying to figure out the best way to select and brighten a few parts. My goal is to lift the brightness of the shadowed portions of the support cables (photo below) so all cables are at a consistent level of white. When I try to use the smart brush or any other selection tools I get a very harsh/aliased line, and when I increase the exposure it doesn't look realistic. Any idea how I might be able to accomplish this selection and what type of filter or adjustment to use to brighten? Eventually I'll be converting to black and white or something similar so the shadowed areas need to be the same value as the rest of the cable or they just disappear into the black. Thanks for any guidance you can provide

[Graymare]

Add a layer above your picture.  Set it to Screen or Overlay.
Add a Mask to this layer.  With an appropriately sized brush, mask just the cable sections that are too dark.  You may need to blur/smudge the areas that softly gradient out.  Click on one end of the cable, and shift-click on the other to draw straight lines with the Brush tool.

Back on the normal layer set on Screen/Overlay, use a white brush to blend out the shadows. Go back and refine the mask as needed.

Alternately you can adjust a copy of that image so the dark cables are the correct brightness and reverse-mask them onto the original, however it looks like some of the areas are quite variable in darkness so I'd feel the former method would yield a more controlled end result in less time. 

[firstdefence]

Another method would be to simply use the pen tool to draw white lines, add a small gaussian blur fx and adjust the stroke to match the cable thickness. You could also add a bit of noise to the stroke when setting the white.

[Jeff_]

Thank you both! Two great solutions, much appreciated.