Change the skin/hair/eyes color of a character

[Nico]

Hello it's me ! (again)

I would like to change the skin/hair/eyes color of characters. I have an exemple with the skin color, white to blue and the eyes color, yellow to blue.
I tried with Hue-Saturation and the result is pretty good BUT I don't know how to erase the blue on the hair. I tried to cut out the hair but it's hard because of the several thin hair on the face. I tried to use Layer Mask but I can't because of the same reason.
In a general way, it's hard for me to change the skin/hair/eyes color on a character so if you have a solution, I'm listening !

The original :

https://zupimages.net/up/21/29/znls.jpg

Then :

https://zupimages.net/up/21/29/490h.png

Thank you in advance !

[denzjos]

Just a try : Make a copy from the drawing to a new layer, inverse this layer color (Colours / invert) and set the layer mode of the color inversed layer to 'Grain extract'. Make a new layer : 'New from Visible' (right click on the layer dock). Use 'Colours / Desaturate / Mono Mixer' to convert the new layer to black and white. Make a color selection (Select / Select by Colour) to select the black or the white (I've selected the white, feather the selection by 2  and invert the selection / search out what is best for you). Copy the original layer to a new layer and 'Apply Layer mask' (right click in the layer dock) and chose selection. Now you can change the color of the skin.  
     

[Nico]

Hello !

Thank you for your reply !

I'm sorry, I must be stupid but I didn't catch all of it (maybe because english is not my first langage lol)

I made the beginning but here : "Make a color selection (Select / Select by Colour) to select the black or the white (I've selected the white, feather the selection by 2 and invert the selection / search out what is best for you)." I am lost. When I select the white (so the skin) Gimp selects also the grey background and not all the skin. It's because of the different shades of the skin, I think.

Could you screen the different steps ? It's boring for you so I will understand if you can't.

And, to change the color of the skin, I must use the brush ? Or the color changes with the color of the inversed layer ? I'm sorry, I think I didn't get it.

[denzjos]

   
   

[Nico]

Ok, thank you, I think we are in progress !

I have this : https://zupimages.net/up/21/29/yuz1.png but the color doesn't work, can you explain why ?

Thanks for your patience !

[denzjos]

Use 'Colours / Hue Saturation' to change the color. On the layer with the mask , make the image active (not the mask). Set the original layer visible.
   

[Nico]

Okey, I think I understand now ! This is not exactly what I was looking for but it's a first solution, thank you ! (and with some practice, I think I will change the color just like you do)

If someone have another solution, my subject is still open !

[PixLab]

Filters > G'MIC_Qt > Contours > Extract Foreground [Interactive]
It does a pretty good job to separate hairs from the skin, You have to spend a bit of time to carefully put your control point.
G'MIC result will be 1 layer for the foreground + 1 layer for the background, which will allow you to do whatever you want to change on either FG/BG

Example In less than a minute, not caring about control points nor playing with the 2 sliders

   

[Nico]

Oh thanks for your help ! It's a bit of practice but it's works !

Thank you both of you !