[Gimp-user] Why is this color mapping not working?

[laredotornado <forums gimpusers com>]

HI, 

I'm using Gimp 2.8.18 on Mac High Sierra.  I want to do what I hope is very
simple -- switch out one color with another.  I wanted to change the white to a
dark gray and teh black to a lighter gray.  I first changed the white color,
which went ok.  Then, I want to change all the black to a gray color -- #D3D3D3.
I open my image, go to the Color menu, and select "Map" and then select "Color
Exchange".   Then I select the relevant colors and click "OK".  However the
result (attached) is disappointing.  It is very difficult to read the numbers in
the scale.  Am I missing something?  Or there others colors at play here?

Thanks for any advice, - Dave

Attachments:
* http://www.gimpusers.com/system/attachments/815/original/scale.jpg
* http://www.gimpusers.com/system/attachments/816/original/scale_gray.jpg

-- 
laredotornado (via www.gimpusers.com/forums)