Coler exchange / re-coloring

Hi here,
I am quite new to Gimp and would like to find out how to re-color (apply a different color) to a section of the imagee, which is not color unique (so I can not use the pointer to select “from color”) ---- so I would need to select the section of the image via the free selection tool. But I want to keep the structre of the image/section and not to simply re-paint and lose the structure of the surface (in my case a roof which I want to change in color but keep the structure of the roof in the image.)
Would be great if anybody can guide me through.
Kind regards

Hello Joachim and welcome to the forum!

You need to duplicate the layer first:

And now you have to work on the upper layer:

Then with free selection tool you select your roof:

Then select foreground color and insert it into the pallet. I have chosen blue here:

Now colorize the roof. Either drag the foreground color into the selection or use the brush and paint the color into the selection:

To keep the details of the roof, you now have to use one of blend modes with which these two layers are combined in such a way that only the color but not the details of the roof are affected.

So you change in the list of blend modes normal

…to LCH color, for example:

You can also try HSV Hue, HSL Color or LCh hue.

Now the roof has changed color without changing the details:

Another possibility would be to “rotate” one color or color range into another using the rotate colors tool (colors - map - rotate colors):

Now you can select a color range with the source range circle and transfer (rotate) it to another color range that you select with the destination range circle:


Can you post a copy of the image or one similar. This technique might work, but depends upon the roof being colored and not just a neutral metal or black.

Colour Swap

  1. Open the image red car and isolate the subject by using the lasso tool to draw a rough selection. The ‘marching ants indicate that the selection is active.
    When the colour swap is applied it will only affect the part of the image within the selection.

  2. Go to Colors > Hue-Saturation and select red as the primary colour to adjust and move the Hue slider to select a new colour.


  1. In this case, there is a magenta cast left on the roof and this can be corrected by selecting magenta as the primary colour to adjust and move the hue to give a suitable shade of colour.

  2. When satisfied with the result click OK to apply the effect and disable the selection.


Dear Terry, hi Boris,
thanks for the first recommendations. I will keep on trying, but have not yet succeded. (e.g. combining the 2 layers/levels and get rid of the marching ants…).
As requested, I attach a sample picture which shows the underside of the roof with the old and faded wood-paint which I want to renew with a more friendly color. If you have any other suggestions, it would be great.

I am not much of a colourer but try this.
Using the same colour you have around your windows, colour pick it to be the foreground colour. Then select all of your wooden under eave area. Add a transparent layer, drop your foreground colour into that selection and bring the opacity of that layer down to 50. Layer mode to darken only.
You should still have your lovely wood grain and a darker nice colour.