Do I need new pistons?

[sgd37]

Three of my pistons look like this.

http://imgur.com/FTx2iwd

http://imgur.com/aGZPg3L

http://imgur.com/F8NTeke

They have some concerning pitting but otherwise they're fine and have no damage. What could have caused this and do they need replacing?

Thanks

[Bryanj]

OK to use if no sieze marks, ring grooves ok and clearance in bore within spec, probably corrosion from not being used a lot

[sgd37]

Thanks for the reply.

The rest of the piston seems to be in spec only some light scuffing and discoloration. Is there anything I can do to get rid of the pitting? skimming, sanding or polishing?

Cheers

[neilg]

I would leave it alone. It will soon be covered in carbon any way and any rubbing down might cause damage around the circumference edge.