Making part of the image black and white in Gimp

Here is a way of making a part of the image B&W in Gimp. The basic idea is to select the portion which we want to change and while keeping it selected, make the changes. In case the part which needs the change is the major portion, it might be easy to select the rest of the portion and then invert the selection. Here I will let the speed and roundabout sign in yellow remain as it is and make changes to the rest of the figure.

(1) Open the image in Gimp

(2) Select the "zoom" tool

(3) Zoom-in on the yellow sign by repeatedly clicking on it

(4) Select the "path" tool

(5) Using the path tool draw the outline of the yellow sign. You will notice that as you click, small circles will be made at the point where you click. Also, the latest point is connected to the previous one making a "path". In order to end or close the path, after you have gone all around the sign, click on the very first circle.


(6) Now from the "select" menu click on "from path"

(7) When you do so the circles and dash line made by the path tool will all be connected, and you have a dash (moving ant like) line on the outline of the yellow sign.

(8) From the "select" menu click on "invert". As of now everything inside the path is selected, with "invert" everything outside the current selection will be selected.

(9) Use the zoom tool to zoom-out to see the full image.

(10) From the "color" menu select "desaturate"

(11) In the picture everything except for the yellow sign will turn B&W. Also you will be presented with three options of how to desaturate. You can click on each and see which you like best.

(12) Now that its B&W, for a final touch we can adjust the contrast. To do so, from the "color" menu select "brightness and contrast".

(13) Use the slider to increase the contrast to the level you want.

(14) Finally, from the "select" menu click on "none" to remove any current selections.

(15) Now that its done, it may be saved in this final version.

There are other methods of doing this but for this image I think this is the simplest way.