Coloriser un dessin au lavis

Another option would be to use the Hue/Saturation adjustment layer where you could select the Colorize option, use the Hue slider to adust the hue, and change the Saturation and Lightness as needed.

One option would be to try colorizing the wash while leaving the black lines by using adjustment layers and layer masks. Here's how:

1.  Use a Levels adjustment layer (click on the middle icon at the bottom of the Layers panel and select Layers... or go to Layer > New Adjustment Layer > Levels...) to make the black lines darker and the background that should be white brighter.
2. Add a Gradient Map adjustment layer (click on the middle icon at the bottom of the Layers panel and select Gradient Map... or go to Layer > New Adjustment Layer > Gradient Map...).
3. The Gradient Map adjustment layer will automatically add a white layer mask, so select an area of the wash that you'd like to make a particular color.
4. Invert that selection (Select > Inverse) and fill that inverted selection with black so that your Gradient Map adjustment layer will only apply to the area revealed by the layer mask.
5. Double-click on the Gradient thumbnail in the Layers panel to open the gradient in the Properties panel, and then double-click on the gradient in the Properties panel to open the Gradient Editor.
6. The Gradient Map will remap the colors on the canvas with the colors in the gradient. If you set the left color stop to black, the right color stop to white, and add a color (such as brown) in the center, then Photoshop will keep the darkest pixels on the canvas black, change all the pixels of varying levels of gray to varying levels of brown, and will keep the white pixels as white. You can adjust the transition between color stops and position of the color stops to affect how the pixels are colored.
7. Repeat steps 2-6 for each color you'd like to add.