gradients on contour maps?

I'm a member of a flight sim mod group. We want to create a new map. Well, the problem are the contour lines of the contour maps. The program uses colors to calculate the height of any point on the map.

The RGB value of '0' is sea level. To change the height the 'R' value has to be increased first. A value of R='1', G='0', B='0' is 4 cm above sea level. This goes as high as R='254', G='0', B='0' for a height of 10,2 m. For greater heights we have to add a green value. This gives us additional 255 red values (0-254). So R='0', G='1', B='0' is 10,24 m up to R='254'. G='1', B='0' for 20,4 m . Then we add green value '2'. And so on! When we reach green='254' we have a height of ~2600m.

This is what it looks like in a TGA-file used for the maps:

URL

So the question is: what is an effective way to draw those contour lines with their corresponding color gradients? My idea was to use the highest color values (R=254 and G= 1-254) as contour lines and then fill the black spaces between them with their corresponding gradients. The problem, however, is that I can define a direction for the gradients but I can't get PS 6 to draw the gradients in a way that they follow parallel to the contour lines!

Can anyone help out here?

Wrong tool, try Illustrator. You will get fine gradients between two curves by blending them.

Interesting! Until now I have drawn greyscale maps and converted them with FSTerrain 2002 to the desired format. But that's not suited for editing. I'll try Illustrator now!

Thank you!