[Gimp-user] global color changes

I am creating test images for an electronic sign.

The image was created in GIMP 2.10.8 and was declared an RGB image
upon startup.

It consists of 24 pairs of rows, one pixel in height and 112 pixels long. Each
pair consists of a black row and a color row.

How to make a single test pattern and then change the color row color with a
simple step(s) to make multiple test images.

I created the original image using a white background upon which I drew black
foreground lines with a pencil..

When sent to the LED sign, the test image should turn on every other pixel so
that Red and Green and Blue LEDs produce white if the pixel is on. Otherwise the
pixel is off.

Now i would like to create another test pattern replacing white with some other

I could select  each white row and change its color using a bucket fill, but
there must be a better way that reduces making all those selections. Since I am
using only the foreground color and background color I thought maybe I could
change the background color and all the spatial regions that were the original
background color would automatically change. However that did not work.

In looking around it seems some people use "color to alpha plugin". 
The only problem is I can not find such a plugin....not even a grayed out

So FIRST....Am i pursuing the most appropriate method of changing the white
background (that is how the white originally was formed) to another color by
using the color to alpha plugin.  IF not please offer an alternative approach.

if so, please help me gain access to the color to alpha plugin.  As mentioned
earlier, I declared the image mode as RGB before I drew
a single line.

One last request....It would be nice if I could reverse the black lines and make
them white lines and repeat the above changes. That would enable me to test the
pixels are not tested in the above test pattern.

Thank you for any input you can offer me.


* http://www.gimpusers.com/system/attachments/1053/original/TeamSign_TestImage_HorizontalLines_R0_B_C0_W.xcf

whburling (via www.gimpusers.com/forums)

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