Baked texture sharpness

Hi, I am having relatively bad texture sharpness when baking a 4K texture on a polysphere. I have disable MipMap and Interpolation in texture settings, which didn’t change much the result. I have also tried various filter types and sizes on the Rendering tab, without much success. Only option I have found for now is to bake a higher resolution texture and then reduce it in Gimp or Photoshop. I would prefer baking directly a proper result in Blender though, any idea? (Blender 2.69).

Not a lot to go on is there ? I suppose this is a test to see which users on the forum are telepathic

Actually I see the projection has upsampled the texture so that explains the lack of sharpness…