I'm making a shaded relief map that uses a scanned map as the color layer. The original map has an off white border and areas of pale blue indicating sea. When rendered with white sunlight the border and the blue sea become nearly the same blue. I'm guessing that the blue tinge across the render is either the result of modelling surface or atmospheric scattering.
I've tried increasing sunlight strength and using two suns - one strong one (>10) at a low angle to cast shadows to bring out the relief and a weaker one (~1) pointing straight down.
I'd like the white to render more white, or at least for the border and the sea to be distinguishable and 'read' as white and blue. How do I achieve this?
(New to Blender, so apologies if I've missed something obvious)
Edit: Setting Roughness to zero or one has little effect. The World color is the default gray, but changing it to white doesn't make a noticeable difference either.
It's possible to get back to something like the original color of the map by exporting the rendered image to Photoshop and adjusting the white balance. Still, I'd like to see that result in the render.
Below - original map, left; render, right: