How do I exchange colors?

[odastein]

Hello,

Keep in mind that it's the first time ever that I'm using GIMP; so I've no clue how one would routinely use any basic function.


So, I want to change the color of pixels in an area of a picture from some kind of brown/purple to black. I selected the area. I opened color/map/exchange color. I selected a sample pixel of the color I want to change to black in "from color". Black is already preselected in "target color" by default. 

Then, what do I do to actually exchange the colors? I clicked on "apply" but the "exchange color" window just closed and nothing happened in my selection. The manual explain explains how to select the origin and target colors, as I wrote above but doesn't say how you actually apply the change.

Thanks in advance.

[Ofnuts]

In practice you have to increase the thresholds for the RGB channels. In a regular image, very few pixels are exactly of a given color, so unless you give some margin very few pixels will be affected by the change.

This said I 've been using Gimp for a while now and I don't remember using color exchange, to there are possibly other/better ways to do what you want. what are you trying to achieve?