What methods can I use to reduce such a visible seam? I never noticed this seam on my rocks till I decided to modify the main texture for them to emit light from some of the low spots. This is a texture on all 6 sides of a cube, and subdivided a few times.

What methods are available to reduce the visibility of this seam?



Edit: Looks like I use texture painting to do what I need! Only issue is is that some sort of symmetry mode is on where both sides of the seam mirror each other.
There are 2 methods worth looking into.


Blended box mapping (cycles / rendering only)Easy to enable and apply everywhere but adds noticeable blurring/blending.
Projection painting - use the clone tool in 3d to clone over the seamGives a lot of control but makes the texture specific to meshes UV's, and wont work for tiling textures. However it can be used anywhere UV textures are supported - exporting to game engines for eg.