Please, how to improve darkness in this PLY: http://18.104.22.168/3d/sodark.zip ? It is too dark! What's the issue?
I think that there is not a Blender-related issue: the vertex colors are the ones the file provide.
Here's what they look like in Meshlab:
And in Blender:
put apart the different viewport shading by seeing the true solid colours in cycles preview or textured mode in blender render, and you'll see no difference:
You can tweak the vertex colors with nodes as liked:
Note that vertex colors are changed only in the viewport, for rendering purpose, not in the vertex color layer. If you want to store a new, brighter, vertex layer you should:
- bake cycles tweaked vertex color to an image texture
- convert the texture to a new vertex color layer