Implementing alternate pallets

Is there a better way to implement alternate palletes then to just use different textures? Like if the pixel color is defined as Blue:

(((R=G)&&(R<192)&&(B=255))||((R=0)&&(G=0)&&(B>64)) )

Then switch around the values for that pixel:

Red:
Temp=R; R=B; B=Temp;

Green:
Temp=G; G=B; B=Temp;

Gray:
R=B; G=B;

Magenta: // Purple
R=B;

Cyan:
G=B;

Yellow:
Temp=G ; R=B; G=B; B=Temp; // G and R must be equal

Where
R = Value of Red
G = Value of Green
B = Value of Blue
From 0 to 255.

Temp is just a placeholder variable to swap numbers.

This is just pseudo code and I'm not sure how it will actualy work, but it will most probably require changing the source for EDuke32 or JFDuke.


Others colors like Orange may be harder to implement.