Re: [Gimp-user] How to control one color only?

[Steve Kinney <admin pilobilus net>]

On 04/11/2012 12:46 PM, Keith Purtell wrote:
> This is another of those things I knew how to do in PShop and am now
> trying to duplicate in GIMP. I have a photo of a flowchart drawn in
> green marker on a whiteboard. Photo taken with an iPhone, so quality
> is yuck. I brought out the greens with Color Enhance, but now the
> white board has areas that are yellow on the right and blue on the
> left. 
>
> How to target these "problem colors" and desaturate or otherwise
> move them back to white?

Hey Keith,

The Select By Color tool might do the trick for you - it's a button
in the top row of the (default) main toolbox.  Turn it on, click in
an "average looking" part of the unwanted color anywhere in the
image, and see how close it comes to getting everything you want to
alter.  In the Tool Options dialog dock, you can adjust the
threshold of this tool to select a wider or narrower range of
colors, image-wide.

Once you have (only) the bits you want to change selected, you can
do any of a number of things:  Drag and drop your color of choice
from the foreground/background tool, use the Colors > Hue/Saturation
tool, or etc.

:o)

Steve