1- Color fill adjustment

The effect is achieved very simply with a color fill adjustment:

  • Create a Color Fill adjustment layer.
  • Set the color to pure red: #FF0000.
  • Now change the blending mode of the adjustment layer to Darken.

The only other adjustments I did to this picture are lighting up the forearms and darkening down the stomach a bit with curves:

2- Dodging the forearms

  • Select the background layer, so that the curves adjustment layer you’ll create will be under the color fill adjustment in the layer order.
  • Create a Curves adjustment layer.
  • Bring the middle of the curve slightly upwards, to lighten up the whole image.
  • Click to select the mask associated with that Curves adjustment layer, hit Cmd+I Ctrl+I to invert the colors and effectively make the mask hide the whole effect.
  • Using a Soft White Brush → B, paint around the forearms to brighten them up and bring back the details.

3- Burning the stomach

  • Now for the stomach, create another Curves adjustment layer.
  • Bring the middle of the curve slightly downwards, to darken up the whole image.
  • Now click to select the mask associated with that adjustment layer, hit Cmd+I Ctrl+I to invert the colors and effectively make the mask hide the whole effect.
  • Using a Soft White Brush → B, paint around the stomach to darken it up.
  • Here I also applied a Gaussian Blur filter to the mask, just to make the effect fade out more subtly. I applied a Gaussian blur with a radius of 190px, but this will vary depending on the size of your image.

Et voilà! A dark image with a stylish red tint with just a simple red color fill adjustment.