Half of mesh looks darker when I attempt to add normal map Alright, so I made a model in blender, and I notice something weird when I create a new image and attach it in the node editor.  My intention is to use a high-poly model I sculpted to bake a normal map onto the low poly mesh.  However, even before I bake the normal, Something weird happens:  One half of the model appears to be darker than the other half.  



The boundary between the light and dark areas of the mesh is exactly where I marked the seams for the UV.  This doesn't disappear when I look at it in either the materials or rendered views, nor does it disappear when I bake the map. After I bake the map, it doesn't disappear when I create a new image and connect it to the normal map either.  I searched around, and the most common fix for problems like this is to look at which directions the normals are facing.  Unfortunately, I've taken a look, and it appears that the normals are already facing the right direction.

Update:  I have solved this problem on the tongue by setting the normal map vector to "UV Map", but this doesn't work on the body mesh.

Extra update:  It doesn't work on any of the other meshes, even ones that have only one material attached to them.  I have no idea why the tongue normal works when nothing else does.
If anyone still suffers from this problem: change the Color Space to Non-Color on the texture node of your normal map.